Sponges

Sponse of sponsdiere is die mees basale klade diere van die filum Porifera (betekenis: "spoordraers").^[1] Hulle is veelsellige organismes van die subkoninkryk Parazoa, en hul lywe is vol porieë en kanale wat water daardeur laat sirkuleer.

Sponse het ongespesialiseerde selle wat in ander soorte selle kan verander en in die proses dikwels migreer tussen die hoof-sellae en die mesohyl (interne gelatienagtige stof). Sponse het nie senu-, verterings- of asemhalingstelsels nie. In plaas daarvan steun die meeste op die handhawing van ’n konstante watervloei deur hul lywe om kos en suurstof te kry en afvalstowwe te verwyder.

Tipes liggaamsbou

Daar kan 3 verskillende tipes liggaamsbou in sponse waargeneem word. Die eenvoudigste tipe word die askonbou genoem en sulke sponse bestaan uit 'n holte, die atrium, wat deur die liggaamswand omsluit word.

Water vloei die atrium deur die porosiete binne en gaan deur die tuit of oskulum (gewoonlik 'n dorsale opening in die sponswand) na buite. Die oskulum is die enigste opening waardeur die water na buite kan vloei en die rigting van die waterstroom word deur die koanosiete bepaal. 'n Tweede soort liggaamsvorm, die sykontipe, is basies 'n askontipe waarvan die liggaamswande baie gevou is.

Die voue bring mee dat ʼn aantal klein holtes gevorm word wat almal in 'n atrium uitmond. Watervloei word ook deur die koanosiete teweeggebring. Die meeste sponse het egter ʼn leukonliggaamsvorm, waar die volume van die atrium verklein is. Die wande is baie gevou en die oorspronklike atriale ruimte is met 'n aantal kanale gevul, wat op hulle beurt weer vertak en klein kamers vorm.

Water vloei die klein kamers deur die porosiete binne en word dan deur kanale van die kamers af weggelei. Die kanale verenig naby die oskulum, waardeur die water na buite gaan. Leukonsponse kan ʼn aantal oskula hê en sommige spesies kom ook in kolonievorm voor.

Fisiologie

Sponse is vir hul lewensfunksies van 'n bestendige waterstroom deur hul liggame afhanklik. Hoewel die waterstroom deur die koanosiete veroorsaak word, hang die tempo daarvan grotendeels van die oskulumgrootte af. Die grootte hiervan word deur gespesialiseerde selle, die miosiete, gereguleer en hulle is in 'n aaneenlopende sirkel om die oskulum gerangskik.

Hulle vergroot die opening deur te ontspan en verklein dit deur saam te trek. Die water word vir gaswisseling gebruik en die kraagselle verkry die voedseldeeltjies uit die water. Volwasse sponse is sessiel: hulle is aan 'n substraat vasgeheg. Hulle larwes kan egter deur 'n aantal motiele (beweeglike) stadia gaan. Sponse kan sowel geslagtelik as ongeslagtelik voortplant.

Die meeste sponse is hermafrodities (tweeslagtig) en slegs 'n klein aantal eenslagtige spesies word aangetref. Die geslagselle (eiers en spermselle) word deur die amoeboïedale selle gevorm en die gamete word op verskillende tye afgeskei sodat selfbevrugting nie kan plaasvind nie. Die larwes wat na bevrugting ontwikkel, gaan deur 'n vryswemmende stadium voordat hulle hulle op die bodem vasheg en tot 'n nuwe individu ontwikkel.

Sponse kan baie maklik ongeslagtelik voortplant omdat hul selle so ongespesialiseerd is. Hulle het ook 'n verbasende regenerasievermoë en enige deel van 'n spons kan vervang word nadat dit afgebreek het. Gedurende ʼn eksperiment is 'n spons byvoorbeeld deur gaasdoek geforseer, en die individuele selle wat aan die ander kant uitgekom het, het weer in klein groepies bymekaargekom om 'n aantal nuwe individue te vorm. Varswatersponse en sommige seelewende spesies het ʼn besondere metode van ongeslagtelike voortplanting ontwikkel.

Tydens ongunstige toestande vergader 'n groot aantal argeosiete en ook reserwevoedsel in die mesofiel om 'n knop te vorm. Die versameling selle word deur ʼn harde beskermende wand omring en die globuleuse struktuur word dan 'n gemmule genoem. Die ouersponse spons sterf gewoonlik hierna, maar die gemmule oorleef die ongunstige toestande. Wanneer die toestande verbeter, stroom die argeosiete by 'n opening in die gemmule uit, kom weer saam en ontwikkel tot 'n nuwe spons.

Kalksponse

Die kalksponse behoort tot die klas Calcarea of Calcispongiae en die klas word deur hul 3- of 4-stralige, los gerangskikte kalkstekels gekenmerk. Die sponse het 'n slap liggaam en hulle word nie groot nie. Alle spesies leef in die see, terwyl hul voorkoms en vorm so baie na gelang van omstandighede kan wissel dat navorsers nie seker is hoeveel spesies daar in die orde is nie.

Glassponse

Glassponse behoort tot die klas Hexactinellida of Hyalospongiae en kom veral in die diepsee voor. Die klas se stekels is of 3-, of 6-stralige naalde, wat tot ʼn ingewikkelde skelet van tot 1 m kan ontwikkel. Byna al die spesies is buisvormig en veral die venusmandjie (Euplectella aspergillum) is vir hul ingewikkelde skelet bekend.

Gewone sponse

Die gewone sponse (klas Demospongiae) is ʼn groot versameling diere wat in ʼn verskeidenheid habitatte voorkom. Hulle kan ryklik gekleurd wees omdat pigmentkorrels (kleurstowwe) in die amebosiete kan voorkom. Die stekels toon ʼn groot verskeidenheid vorme en hulle is in spongienvesels ingebed en vorm (in baie gevalle) ʼn geraamte.

Die bekendste gewone sponse is die badsponse (genera Spongia en Hippospongia), waarvan daar etlike duisende kilogramme jaarliks geoes word. Sommige wetenskaplikes het voorgestel dat daar 'n vierde klas sponse onderskei moet word. Hulle het die naam Sclerospongiae voorgestel vir 'n leukon-tipe spons wat ʼn inwendige geraamte van silikastekels en 'n uitwendige bedekking van kalsiumkarbonaat het.

Oorsig

Sponse in die water, onder meer geelbuissponse (Aplysina fistularis), persvaassponse (Niphates digitalis), rooikorssponse (Spiratrella coccinea) en grystousponse (Callyspongia-spesies).

Sponse stem met ander diere ooreen in die sin dat hulle meersellig en heterotroof (kan nie hul koolstofvoeding uit anorganiese verbindings trek nie) is, nie selwande het nie en spermselle vervaardig. Anders as ander diere het hulle nie ware weefsel, organe en liggaamsimmetrie nie.

Die vorms van hul liggaam is aangepas vir die maksimum watervloei deur die sentrale opening, waar dit voedingstowwe deponeer. Die water verlaat weer die organisme deur ’n opening, die oskulum. Baie sponse het interne skelette van kollageenproteïen en/of sponsnaalde van kalsiumkarbonaat of silikondioksied. Alle sponse is onbeweeglike waterdiere. Hoewel sommige in varswater voorkom, is die meeste seewaterspesies.

Die meeste van die sowat 5 000 tot 10 000 bekende spesies leef van bakterieë en ander voedseldeeltjies in die water, maar sommige het fotosintetiese mikro-organismes as simbionte, en hierdie bondgenootskappe produseer dikwels meer kos en suurstof as wat dit gebruik. ’n Paar spesies wat in omgewings met min kos voorkom, het karnivore geword wat hoofsaaklik op klein skaaldiere aas.^[2]

Die meeste spesies plant seksueel voort deur sperma in die water vry te stel om eiers te bevrug. Die eiers word by sommige spesies in die water vrygestel en by ander deur die "moeder" behou. Die bevrugte eiers bring larwes voort wat wegswem op soek na vasklouplek. Sponse kan ook voortplant deur deeltjies wat afbreek, maar dan moet dit die regte soort selle wees.

’n Paar spesies plant voort deur knopvorming. Wanneer toestande versleg, soos wanneer dit kouer word, kan baie varswaterspesies en ’n paar seesoorte gemmule voortbring; dit is "oorlewingspeule" van onbepaalde selle wat rustend bly todat toestande verbeter. Daaruit kan hele nuwe sponse voortkom, of dit kan die skelette van hul ouers rekoloniseer.^[3]

Verwysings

Eksterne skakels

• Wêreldspektrum, 1982, ISBN 0908409672, volume 26, bl. 102, 103

• "Water flow and feeding in the phylum Porifera (sponges)"
• Carsten's Spongepage, "Information on the ecology and the biotechnological potential of sponges and their associated bacteria".
• "The Sponge Reef Project"

• Wikispecies het meer inligting verwant aan: Sponsdier

• Wikimedia Commons het meer media in die kategorie Sponsdier.

Los poríferos (Porifera) o esponxes son un filu d'animales invertebraos acuáticos que s'atopen enclavaos dientro del subreinu Parazoa. Son mayoritariamente marinos, sésiles y escarecen d'auténticos texíos. Son filtradores gracies a un desenvueltu sistema acuíferu de poros, canales y cámares que xeneren corrientes d'agua provocaos pol movimientu d'unes célules flaxelaes: los coanocitos. Esisten unes 9000 especies d'esponxes nel mundu, de les cualos solo unes 150 viven n'agua duce.^[1] Conócense fósiles d'esponxes (una hexactinélida) dende'l Períodu Ediacáricu (Neoproterozoicu o Precámbricu cimeru).^[2] Consideráronse plantes hasta qu'en 1765 afayóse la esistencia de corrientes internes d'agua y fueron reconocíos como animales. La so dixestión ye intracelular. Les esponxes son el grupu hermanu de tolos demás animales. Les esponxes fueron les primeres en ramificase del árbol evolutivu dende l'ancestru común de tolos animales.^[3]

Carauterístiques xenerales

Una de les carauterístiques más sorprendentes de les esponxes ye que la mayoría de les célules que componen el so cuerpu son totipotentes, esto ye, puen tresformase en cualesquier de los otros tipos celulares según les necesidaes del animal. Por tantu, considérase que les esponxes tienen una organización celular, a diferencia del restu de metazoos que la so organización ye tisular (con texíos). Escarecen de verdaderes capes embrionaries.

La forma corporal xeneralizada d'estos animales ye la d'un sacu" con una abertura grande na parte cimera, el ósculo, que ye por onde sale l'agua, y munchos poros más o menos pequeños nes parés, que ye por onde entra l'agua. La filtración del alimentu producir na cámara interna del animal, y ye llevada a cabu por un tipu celular especializáu y únicu de los poríferos, los coanocitos. Estes célules tienen una gran semeyanza colos protozóos coanoflagelados, polo que güei hai poques duldes de que tán rellacionaos filoxenéticamente. Les esponxes, los metazoos más primitivos, tuvieron probablemente un antecesor común colos coanoflagelados coloniales, similares seique a los actuales Proterospongia o Sphaeroeca que son simples amestaos d'animales unicelulares.

Les esponxes son práuticamente incapaces de movese; munches escarecen de simetría corporal y por tantu nun tienen una forma definida; hai que crecen indefinidamente hasta qu'atopen con otra esponxa en crecedera o otra torga, otres que s'encuallen en roques, furándoles, etc. Una especie determinada pue adoptar distintos aspeutos según les condiciones ambientales, como la naturaleza y enclín del sustratu, disponibilidá d'espaciu, corrientes d'agua, etc.

Les esponxes escarecen de boca y d'aparatu dixestivu y a diferencia del restu de metazoos dependen de la dixestión intracelular, colo que la fagocitosis y pinocitosis son los mecanismos utilizaos pa la ingestión d'alimentu. Tampoco tienen célules nervioses, son los únicos animales qu'escarecen de sistema nerviosu.

Referencies

Süngərlər (lat. Porifera, Spongia) - onurğasız heyvanlar tipi. 8000-ə yaxın növü təsnif edilib. Əksər növləri dənizdə yaşasalar da, bəzi nümayəndələri (məsələn gölsüngəri) Antarktidadan başqa digər materiklərin daxili sularında rast gəlinir.

Süngərlər çoxhüceyrəli heyvanların ən ibtidai nümayəndələridir. Bədən iki hüceyrə qatından: xarici-ektoderma və daxili entodermadan ibarətdir. Bu qatlar arasında isə ayrı-ayrı hüceyrələr səpələnmiş, quruluşsuz xüsusi maddələrdən ibarət olan qatmezoqley yerləşir.

Süngərlər qadiəsi ilə əşyaya yapışır, ağız isə yuxarı yönəlir. Bədən divarı çoxlu nazik məsamələrə malikdir. Süngərlərin bədəni asanlıqla qırılır və ya ovulur. Bədən ölçüsü bir neçə millimetrdən 2 m-ə qədər və daha böyük, rəngi sarı, yaşıl, qırmızı, qəhvəyi, narıncı, bəzən də bənövşəyi olur.

Süngərlərin skeleti kirəc, silisium və buynuz maddəsindən ibarətdir.

Süngərlər suda həll olmuş oksigenlə tənəffüs edir. Bədən daxilinə və kanallara daxil olmuş su axını yaxında yerləsmiş hüceyrələri və mezoqleyi oksigenlə təchiz edir.

Dənizdə və şirin sularda yaşayırlar. Dənizin dibində oturaq həyat kecirirlər. 5000 növü məlumdur. Xəzər dənizdə 3 forması olan bir növü vardır.

Ar spoue eo al loened divellkeinek a ya d'ober ar skourrad Porifera. Bevañ a reont en dour (er mor evit an darn vrasañ anezho) a silont evit en em vagañ.

Meur a stumm zo gant ar spoue met an holl anezho a chom stag ouzh un diaz kalet bennak.

korfadurezh

Brastres ur spoueenn. 1 : oskulom ; 2 : kavenn ; 3 : gwiskad kelligoù diabarzh ; 4 : toulligoù ; 5 : gwiskad kelligoù diavaez

Daou wiskad kelligoù, etrezo un danvez jel-heñvel, a ya d'ober anezho :

• Ar gwiskad diavaez (ar pinakoderm) a c'hoarvez eus kelligoù plat (ar pinakokit) a laosk plas amañ a-hont d'an toulligoù hag o deus ur roll en eskemmoù etre ar spoueenn hag hec'h endro.

• Meur a gellig disheñvel zo en danvez etre-gwiskad, en o zouez ar spikulennoù kalkek pe silikek a ya d'ober un astez skeledenn.

• Ar gwiskad diabarzh zo kelligoù ispisial ennañ (ar c'hoanokit) a zo o roll krouiñ ur red-dour er gavenn (lodenn ziabarzh ar spoueenn) a-benn pourchas boued d'an organeg.

ar c'hoanokit e ruz, ar pinakokit e melen, red an dour e glas sklaer

Tremen a ra an dour dre an toulligoù hag elfennoù magus a chom stag ouzh ar brec'hioù tro-dro da skourjez ar c'hoanokit. Skarzhet e vez an dour dre an oskulom.

Kevrennadoù

3 c'hevrennad spoue a zo.

• spoue silikek :
  • demospongiae (sk. : avu melen, fiez-mor, kouign-rouanez)
  • hexactinellida
• spoue kalkek :
  • calcarea

Les esponges o porífers (Porifera ) són un embrancament d'animals simples i primitius ja coneguts des de temps remots. Aristòtil, tres segles abans de Crist, esmenta ja en els seus escrits a alguns d'aquests éssers, dels quals va fer interessants observacions. L'acceptació del clade Epitheliozoa comportaria que aquest tàxon és parafilètic, car els eumetazous en descendeixen.

Història

Les esponges eren ja utilitzades pels grecs, que en les tèbies aigües de l'arxipèlag hel·lènic, des de temps immemorial, es van dedicar a la seva pesca, en què van arribar a ser molt hàbils. No sols les utilitzaven en la higiene personal, sinó també per a folrar per dins els cascos de bronze i pesants armadures de guerra.

La classificació d'aquest grup dins del món animal o vegetal va constituir un veritable problema per als científics, ja que en trobar iode en el seu cos es creia que eren vegetals. Fins ben entrat el segle XVIII, l'origen de les esponges es va justificar de diverses maneres, primer com a escuma de mar solidificada, després com nius de certs animals marins o com a plantes.

Va ser l'anglès John Ellis, el 1786, qui va resoldre definitivament l'enigma, declarant que les esponges són, de fet, membres del regne animal. Ellis va observar els moviments de retracció i expansió dels porus del cos de l'esponja, així com els corrents d'aigua que els travessen el cos.

No obstant això, a les esponges, els manquen algunes característiques dels animals típics: no tenen teixits totalment diferenciats. En certa manera, es podrien considerar equivalents a colònies de cèl·lules on cadascuna continua alimentant-se per si mateixa.

Característiques generals

Les esponges presenten cambres interiors revestides de coanòcits, cèl·lules que contenen un llarg flagel i un collar. Aquestes cèl·lules fagociten les partícules alimentàries de l'aigua que flueix a través del cos de l'esponja i del seu sistema de canals, impulsada per incomptables sacsejades dels flagels.

Les colònies d'animals que no es desplacen en el mar necessiten que els corrents portin partícules alimentàries fins a la proximitat dels seus òrgans de captura, com els flagells o tentacles. Però les esponges, gràcies a les cèl·lules que produeixen aquest corrent d'aigua en el seu interior, poden viure també en aigües quietes, amb l'única condició que contingui substàncies nutritives.

El bombament de la colònia aporta, sense parar, aigua nova que, amb les seves partícules en suspensió, travessa el cos de l'esponja pels milers de porus que presenten, i arriba a les cèl·lules. Aquestes aprofiten l'oxigen dissolt en l'aigua i, a més a més, capturen l'aliment. Després, l'aigua és llançada una altra vegada cap a fora per l'òscul, i arrossega els materials de desfeta i diòxid de carboni produïts per l'esponja.

Reproducció

Les esponges presenten dos tipus de reproducció: sexual i asexual.

• La reproducció sexual: els òvuls i els espermatozoides es produeixen a partir de determinades cèl·lules dels mesènquima. Els espermatozoides són expulsats per l'òscul en grans quantitats, i poden penetrar en una altra esponja arrossegats pel corrent d'aigua. Una vegada dintre, arriben fins als òvuls i es produeix la fecundació. Els zigots es transformen en larves ciliades que són alliberades a l'aigua, on podran transformar-se en esponges adultes.
• La reproducció asexual: la reproducció asexual es produeix per la separació de fragments de l'esponja, que es dispersen en l'aigua i posteriorment es converteixen en esponges individuals. Avui es creu que les esponges provenen evolutivament dels protozous flagel·lats. Sembla que no són avantpassats de cap altre grup d'animals i que, més aviat, constitueixen una branca sense continuïtat en l'arbre evolutiu.

Fisiologia

Les esponges no tenen aparell digestiu, ni circulatori, ni respiratori. L'oxigen arriba directament a les cèl·lules per difusió. Les substàncies residuals són expulsades lliurement, a través de la paret o per l'obertura que tenen en un extrem anomenada òscul.

El moviment dels flagels dels coanòcits produeix un flux d'aigua que entra pels porus, passa a la cavitat central o atri i surt per l'òscul.

Les partícules orgàniques que hi ha en suspensió en l'aigua són atrapades i digerides pels coanòcits i les cèl·lules fagocitàries que recobreixen els canals de les esponges. Les substàncies resultants d'aquesta digestió poden passar al mesènquima i alimentar altres cèl·lules.

Varietats d'esponges

Classificació

└─o Metazoa

├─o │ ├─o Epitheliozoa │ │ ├─o Homoscleromorpha │ │ ├─? Chancelloriida (extint) │ │ │ │ │ └─o Eumetazoa │ │ │ └─o Calcarea o Calcispongia │ ├─o Heteractinida (extint) │ ├─o Thalamida (extint) │ └─o │ ├─o Calcinea │ └─o Calcaronea └─o Silicea ├─o Hexactinellida │ ├─o Protospongioidea (extint) │ └─o │ ├─o Dictyospongioidea (extint) │ ├─o Dierespongioidea (extint) │ └─o │ ├─o Hemidiscosa (extint) │ ├─o Amphidiscosida │ └─o Hexasterophora └─o ├─o Archaeocyatha (extint) │ ├─o Anthocyathea (extint) │ ├─o Monocyathea (extint) │ └─o Archaeocyathea (extint) └─o Demospongiae ├─? Lithistida ├─? │ ├─o Keratosa │ └─o Myxospongiae └─o ├─o Haplosclerida └─o ├─o Spongillina └─o ├─o Tetractinellida └─o altres tàxons └─o Poecilosclerida i Hadromerida 

Vegeu també

• Esponja de bany.

Anifeiliaid syml o'r ffylwm Porifera yw sbyngau. Maen nhw'n byw mewn dŵr, fel arfer yn y môr. Mae'r sgerbwd yn gallu cael ei ddefnyddio i ymolchi, ond heddiw mae'r mwyafrif o sbyngau ymolchi yn synthetig.

Porifera pod fluorescenčním mikroskopem

Houbovci (Porifera), či také houby (neplést s říší Fungi) nebo živočišné houby, jsou jednodušší většinou mořští živočichové s vakovitým tělem, výjimečně mohou dosahovat průměru až 2,5 metru (druh Xestospongia muta).^[1] Bývají většinou asymetrické jen místy s náznaky paprsčité symetrie. Žijí přisedle, jen larvy jsou plovoucí. Buňky nevytvářejí pravé tkáně, metabolizují a dýchají samy za sebe, mnohé mohou měnit funkci podle změny umístění. Živí se filtrováním drobných organismů z vody. Jsou to hermafrodité, nebo gonochoristi. Množí se i nepohlavně pučením, tvořením gemulí, ale i po odlomení části, neboť mají ohromnou schopnost regenerace.

Stavba těla

Vnější vrstva buněk se nazývá ektoderm (pinakoderm) a je tvořena převážně plochými buňkami pinakocyty. Vnitřní vrstva je tvořena tzv. gastrodermem, který je z velké části tvořen límečkovitými buňkami (choanocyty - velmi se podobají Choanoflagelátům). Obě dvě vrstvy spojuje mezoglea, což je rosolovitá mezibuněčná hmota, ve které se vyskytují i některé buňky (skleroblasty, spongoblasty, amoebocyty). V této vrstvě se nachází i kostra ze skleritů (jehlice) různých tvarů pospojované pružným sponginem; jehlice SiO₂, CaCO₃ (produkovaný skleroblasty) a spongin (produkovaný spongoblasty).

Houby nemají ani náznak nervové soustavy, přesto reagují na podráždění, nebo změny prostředí otvíráním či uzavíráním vstupů vodních kanálků.

Typy buněk

Spongia lamella

• pinakocyty: krycí buňky; pokryv těla, výstelka kanálků
• choanocyty: límečkovité buňky s bičíkem, které v podstatě vytvářejí vnitřní epitel. Dochází v nich k fagocytóze potravy.
• amebocyty: roznos potravy a vynášení metabolitů
• skleroblasty: tvorba jehlic z (SiO₂, CaCO₃) jinak nazývaných spikuly
• spongoblasty: produkce sponginu (rohovitá pružná hmota)
• archeocyty: jsou kulovitého tvaru; nejsou rozlišené a vznikne z nich co je zrovna třeba; tvoří pohlavní buňky při pohlavním rozmnožování
• pohlavní buňky: vznikají z archeocytů, ale i z jiných typů buněk včetně choanocytů; nejsou vytvořeny pravé gonády
• porocyty: vřetenovitě protáhlé buňky s funkcí svalových buněk

Porifera ze třídy Hexactinellida

Tělní typy

• Ascon: nejjednodušší typ; kanálky, kterými nasává vodu, jsou v podstatě rovné a choanocyty jen ve spongocoelu (trávicí dutina).
• Sycon: choanocyty jsou soustředěny v přívodních kanálcích, které bývají částečně rozšířeny do komůrek.
• Leucon: mohutně zesílená stěna (velké zvětšení objemu) protkána sítí kanálků (tzv. alveoly) spojujících mezi sebou komůrky vystlané choanocyty; V 1 mm³ je vytvořeno až 10 000 komůrek, v každé asi 50 choanocytů; v evoluci jsou nejdále především tím, že dokázaly zvětšit trávicí plochu vchlípením a vytvořením komůrek

Fosilní Porifera Hazelia

• Askonní typ

• Syconní typ

• Leukonní typ

Výživa

Houby se živí filtrováním drobných organismů z vody. Pohyb vody tělem je způsoben vířením bičíků choanocytů, které vystýlají buď centrální dutinu (spongocoel), nebo kanálky a komůrky (22 cm velká houba - Leucandra - prožene svým tělem 22,5 l vody denně). Potravní částice jsou vychytávány choanocyty, potrava může být částečně rozrušena již v centrální dutině, pak je dále zpracovávána a roznášena amoebocyty. Nestrávené zbytky a produkty metabolismu odchází spolu s vodou osculem (otvor na vrcholu houby) zpět do vody.

Rozmnožování

Houbovci se množí pohlavně i nepohlavně.

Houba mycí

Nepohlavně se houby množí pučením nového jedince z těla původního. Pučení může být vnější - pak vzniká rovnou nový jedinec, nebo vnitřní, pak vzniká tzv. gemule.^[2] Gemule je malý kulovitý útvar, který je krytý obalem ze sponginu a jehliček (stejné jako vnitřní kostra houbovců) a uvnitř je větší množství archeocytů. Gemule tvoří převážně sladkovodní houby, které takto zajišťují přežití nepříznivého období (zimy) a po jeho skončení vyroste nový jedinec (z každé buňky jeden). Gemule snese vymrznutí i vyschnutí a mohou být přenášeny např. na peří ptáků na nová stanoviště.

Co se týče pohlavních typů rozmnožování, houby jsou mnohdy hermafrodité, nebo jsou vzácně i gonochoristé^[2] a v průběhu života tyto stavy mohou měnit. Jsou však i druhy, které mají určené pohlaví a měnit ho nemohou.

Spermie vznikají většinou z choanocytů, zatímco vajíčka spíše z archeocytů, v podstatě ale mohou vznikat pohlavní buňky z jakékoliv buňky. Spermatocyty se do těla druhého jedince dostávají stejnou cestou jako potrava.^[2] Plovoucím (pohyblivým) stadiem je larva, a to buď obrvená coeloblastula a amfiblastula, které se vyvíjí už mimo tělo dospělce, nebo parenchymula, která se částečně vyvíjí ještě před opuštěním mateřského těla. Vývoj se dokončí až po přisednutí larvy k podkladu.

Rozšíření

Porifera

Jedná se pouze o vodní živočichy, z nichž většina je mořská. V moři se vyskytují od hloubek 1000 m až k přílivové čáře po celém světě. Sladkovodní druhy jsou pouze ve skupině Desmospongiae. V ČR se vyskytuje asi 6 druhů, které jsou ohrožené znečištěním vod.

Systém

Systematika recentních houbovců není jednoznačná. Převládá řazení do několika tříd, ke třem "klasickým" (vápenatí - Calcarea, křemití - Hexactinellida a rohovití - Demospongiae) v poslední době přibyla vyčleněním z rohovitých čtvrtá - plakiny (Homoscleromorpha). Pro vymřelé skupiny houbovců se zavádějí další třídy (Heteractinida, Archaeocyatha).

Dlouho nevyjasněné bylo i fylogenetické postavení houbovců. Původní představy vycházející z morfologie a podobnosti choanocytů s buňkami trubének kladly houbovce jako bazální skupinu živočichů, sesterskou ke všem ostatním. Molekulární analýzy pak naznačovaly, že se pravděpodobně jedná o taxon parafyletický, možná polyfyletický^[3]). Novější analýzy změnily představy o bazálním postavení - první odštěpující se linií živočichů se dnes jeví žebernatky. Houbovci pak tvoří sesterskou skupinu ke zbytku živočichů (vločkovci, žahavci a bilateria). V takovém případě již vycházejí houbovci z analýz jako monofyletická skupina, tvořená dvěma větvemi. Jednou větví jsou křemití + rohovití, druhou vápenatí + plakiny.^[4]

Níže uvedený systém recentních houbovců je z r. 2011,^[5] české názvy taxonů dle BioLibu^[6]:

Kmen PORIFERA Grant, 1826

• Třída Homoscleromorpha Dendy, 1905 – plakiny

  • Řád Homosclerophorida Dendy, 1905

    • Čeleď Plakinidae Schulze, 1880
    • Čeleď Oscarellidae Lendenfeld, 1887

• Třída Demospongiae Sollas, 1885 – rohovití (pravděpodobně parafyletická)

  • Řád Spirophorida Bergquist & Hogg, 1969

    • Čeleď Tetillidae Sollas, 1886
    • Čeleď Samidae Sollas, 1886
    • Čeleď Spirasigmidae Hallmann, 1912

  • Řád Astrophorida Sollas, 1888

    • Čeleď Ancorinidae Schmidt, 1870
    • Čeleď Calthropellidae Lendenfeld, 1906
    • Čeleď Geodiidae Gray, 1867
    • Čeleď Pachastrellidae Carter, 1875
    • Čeleď Thoosidae Cockerell, 1925
    • Čeleď Thrombidae Sollas, 1888

  • Řád Hadromerida Topsent, 1928

    • Čeleď Acanthochaetetidae Fischer, 1970
    • Čeleď Clionaidae d’Orbigny, 1851
    • Čeleď Hemiasterellidae Lendenfeld, 1889
    • Čeleď Placospongiidae Gray, 1867
    • Čeleď Polymastiidae Gray, 1867
    • Čeleď Spirastrellidae Ridley & Dendy, 1886
    • Čeleď Stylocordylidae Topsent, 1928
    • Čeleď Suberitidae Schmidt, 1870
    • Čeleď Tethyidae Gray, 1867
    • Čeleď Timeidae Topsent, 1928
    • Čeleď Trachycladidae Hallmann, 1917

  • Řád Chondrosida Boury-Esnault & Lopès, 1985

    • Čeleď Chondrillidae Schmidt, 1862
    • Čeleď Halisarcidae Vosmaer, 1885

  • Řád ‘Lithistida’ (polyfyletický)

    • Čeleď Azoricidae Sollas, 1888
    • Čeleď Corallistidae Sollas, 1888
    • Čeleď Desmanthidae Topsent, 1893
    • Čeleď Isoraphinidae Schrammen, 1924
    • Čeleď Macandrewiidae Schrammen, 1924
    • Čeleď Neopeltidae Sollas, 1888
    • Čeleď Phymaraphiniidae Schrammen, 1924
    • Čeleď Phymatellidae Schrammen, 1924
    • Čeleď Pleromidae Sollas, 1888
    • Čeleď Scleritodermidae Sollas, 1888
    • Čeleď Siphonidiidae Lendenfeld, 1903
    • Čeleď Theonellidae Lendenfeld, 1903
    • Čeleď Vetulinidae Lendenfeld, 1903

  • Řád Poecilosclerida Topsent, 1928
    • Podřád Microcionina Hajdu, Van Soest & Hooper, 1994
      • Čeleď Acarnidae Dendy, 1922
      • Čeleď Microcionidae Carter, 1875
      • Čeleď Raspailiidae Hentschel, 1923
      • Čeleď Rhabderemiidae Topsent, 1928
    • Podřád Myxillina Hajdu, Van Soest & Hooper, 1994
      • Čeleď Chondropsidae Carter, 1886
      • Čeleď Coelosphaeridae Hentschel, 1923
      • Čeleď Crambeidae Lévi, 1963
      • Čeleď Crellidae Hentschel, 1923
      • Čeleď Dendoricellidae Hentchel, 1923
      • Čeleď Desmacididae Schmidt, 1873
      • Čeleď Hymedesmiidae Topsent, 1928
      • Čeleď Iotrochotidae Dendy, 1922
      • Čeleď Myxillidae Topsent, 1928
      • Čeleď Phellodermidae Van Soest & Hajdu, 2002
      • Čeleď Tedaniidae Ridley & Dendy, 1886
    • Podřád Mycalina Hajdu, Van Soest & Hooper, 1994
      • Čeleď Cladorhizidae de Laubenfels, 1936
      • Čeleď Desmacellidae Ridley & Dendy, 1886
      • Čeleď Esperiopsidae Hentschel, 1923
      • Čeleď Guitarridae Burton, 1929
      • Čeleď Hamacanthidae Gray, 1872
      • Čeleď Isodictyidae Dendy, 1924
      • Čeleď Merliidae Kirkpatrick, 1908
      • Čeleď Mycalidae Lundbeck, 1905
      • Čeleď Podospongiidae de Laubenfels, 1936
    • Podřád Latrunculina Kelly & Samaai, 2002
      • Čeleď Latrunculiidae Topsent, 1922
  • Řád Halichondrida Gray, 1867

    • Čeleď Axinellidae Carter, 1875
    • Čeleď Bubaridae Hentschel, 1914
    • Čeleď Dictyonellidae Van Soest, Diaz & Pomponi, 1990
    • Čeleď Halichondriidae Vosmaer, 1887
    • Čeleď Heteroxyidae Dendy, 1905

  • Řád Agelasida Hartman, 1980

    • Čeleď Agelasidae Lister, 1900
    • Čeleď Astroscleridae Verril, 1907

  • Řád Haplosclerida Topsent, 1928
    • Podřád Haplosclerina Topsent, 1928
      • Čeleď Callyspongiidae de Laubenfels, 1936
      • Čeleď Chalinidae Gray, 1867
      • Čeleď Niphatidae Van Soest, 1980
    • Podřád Petrosina Boury-Esnault & Van Beveren, 1982
      • Čeleď Phloeodictyidae Carter, 1882
      • Čeleď Petrosiidae Van Soest 1980
      • Čeleď Calcifibrospongiidae Hartman, 1979
    • Podřád Spongillina Manconi & Pronzato, 2002
      • Čeleď Lubomirskiidae Rezvoi, 1936
      • Čeleď Malawispongiidae Manconi & Pronzato, 2002
      • Čeleď Metaniidae Volkmer-Ribeiro, 1986
      • Čeleď Metschnikowiidae Czerniawsky, 1880
      • Čeleď Potamolepidae Brien, 1967
      • Čeleď Spongillidae Gray, 1867
  • Řád Dictyoceratida Minchin, 1900

    • Čeleď Ircinidae Gray, 1867
    • Čeleď Thorectidae Bergquist, 1978
    • Čeleď Spongiidae Gray, 1867
    • Čeleď Dysideidae Gray, 1867
    • Čeleď Verticillitidae Steinmann, 1882

  • Řád Dendroceratida Minchin, 1900

    • Čeleď Darwinellidae Merejkowsky, 1879
    • Čeleď Dictyodendrillidae Bergquist, 1980

  • Řád Verongida Bergquist, 1978

    • Čeleď Aplysinellidae Bergquist, 1980
    • Čeleď Aplysinidae Carter, 1875
    • Čeleď Ianthellidae Hyatt, 1875
    • Čeleď Pseudoceratinidae Carter, 1885

• Třída Calcarea Bowerbank, 1864 – vápenatí
  • Podtřída Calcinea Bidder, 1898
    • Řád Clathrinida Hartman, 1958

      • Čeleď Clathrinidae Minchin, 1900
      • Čeleď Leucaltidae Dendy & Row, 1913
      • Čeleď Leucascidae Dendy, 1893
      • Čeleď Leucettidae e Laubenfels, 1936
      • Čeleď Soleneiscidae Borojevic, Boury-Esnault & Vacelet, 1990
      • Čeleď Levinellidae Borojevic & Boury-Esnault, 1986

    • Řád Murrayonida Vacelet, 1981

      • Čeleď Lelapiellidae Borojevic, Boury-Esnault & Vacelet, 1990
      • Čeleď Murrayonidae Dendy & Row, 1913
      • Čeleď Paramurrayonidae Vacelet, 1967

  • Podtřída Calcaronea Bidder, 1898
    • Řád Leucosolenida Hartman, 1958

      • Čeleď Leucosoleniidae Minchin, 1898
      • Čeleď Amphoriscidae Dendy, 1892 - houbatkovití
      • Čeleď Grantiidae Dendy, 1892
      • Čeleď Heteropiidae Dendy, 1893
      • Čeleď Lelapiidae Dendy & Row, 1913
      • Čeleď Sycettidae Dendy, 1892
      • Čeleď Jenkinidae Borojevic, Boury-Esnault & Vacelet, 2000
      • Čeleď Achramorphidae Borojevic, Boury-Esnault, Manuel & Vacelet, 2002
      • Čeleď Sycanthidae Lendenfeld, 1891

    • Řád Lithonida Vacelet, 1981

      • Čeleď Minchinellidae Dendy & Row, 1913
      • Čeleď Petrobionidae Borojevic, 1979

    • Řád Baerida Borojevic, Boury-Esnault & Vacelet, 2000

      • Čeleď Baeriidae Borojevic, Boury-Esnault & Vacelet, 2000
      • Čeleď Trichogypsiidae Borojevic, Boury-Esnault & Vacelet, 2000
      • Čeleď Lepidoleuconidae Vacelet, 1967

• Třída Hexactinellida Schmidt, 1870 - křemití
  • Podtřída Amphidiscophora Schulze, 1886
    • Řád Amphidiscosida Schrammen, 1924

      • Čeleď Hyalonematidae Gray, 1857
      • Čeleď Monorhaphididae Ijima, 1927
      • Čeleď Pheronematidae Gray, 1870

  • Podtřída Hexasterophora Schulze, 1886
    • Řád Hexactinosida Schrammen, 1903

      • Čeleď Aphrocallistidae Gray, 1867 - křemitkovití
      • Čeleď Auloplacidae Schrammen, 1912
      • Čeleď Craticulariidae Rauff, 1893
      • Čeleď Cribrospongiidae Roemer, 1864
      • Čeleď Dactylocalycidae Gray, 1867
      • Čeleď Euretidae Zittel, 1877
      • Čeleď Farreidae Gray, 1872
      • Čeleď Tretodictyidae Schulze, 1886

    • Řád Aulocalycoida Tabachnick & Reiswig, 2000

      • Čeleď Aulocalycidae Ijima, 1927
      • Čeleď Uncinateridae Reiswig, 2002

    • Řád Fieldingida Tabachnick & Janussen, 2004

      • Čeleď Fieldingiidae Tabachnick & Janussen, 2004

    • Řád Lychniscosida Schrammen, 1903

      • Čeleď Aulocystidae Schulze, 1886
      • Čeleď Diapleuridae Ijima, 1927

    • Řád Lyssacinosida Zittel, 1877

      • Čeleď Euplectellidae Gray, 1867
      • Čeleď Leucopsacidae Ijima, 1903
      • Čeleď Rossellidae Gray, 1872

Další zajímavosti

• houby vytvářejí velké množství toxinů, které jsou schopny v případě ohrožení vypouštět do prostředí (jsou zkoumány za účelem hledání nových léčiv)
• houby mívají symbiotické bakterie, či sinice, které jsou někdy zodpovědné za zbarvení hub
• u fosilních druhů často splývaly jehlice v silné desky
• český termín houbovci byl v odborných kruzích zaveden relativně nedávno pro odlišení skupin Porifera a Fungi

Odkazy

Reference

1. ↑ McClain C. R.; et al. (2015). Sizing ocean giants: patterns of intraspecific size variation in marine megafauna. PeerJ 3:e715 https://doi.org/10.7717/peerj.715
2. ↑ ^{a b c} Bílý, M.; Hájek, J.; Koutecký, P.; Kratzerová, L. Rozmnožování organismů. Praha: Ústřední komise biologické olympiády, 2000.
3. ↑ OSIGUS, Hans-Jürgen; EITEL, Michael; BERNT, Matthias, DONATH, Alexander; SCHIERWATER, Bernd. Mitogenomics at the base of Metazoa. Molecular Phylogenetics and Evolution [online]. 25. červenec 2013. Svazek 69, čís. 2, s. 339–351. Dostupné online. ISSN 1055-7903. DOI:10.1016/j.ympev.2013.07.016. PMID 23891951. (anglicky)
4. ↑ WHELAN, Nathan V.; KOCOT, Kevin M.; MOROZ, Leonid L., HALANYCH, Kenneth M. Error, signal, and the placement of Ctenophora sister to all other animals. Proceedings of the National Academy of Sciences USA (PNAS) [online]. 20. duben 2015. S. 1-6. Online před tiskem. Dostupné online. ISSN 1091-6490. DOI:10.1073/pnas.1503453112. (anglicky)
5. ↑ HOOPER, John N. A.; VAN SOEST, Rob W. M.; PISERA, Andrzej. Phylum Porifera. Zootaxa [online]. 23. prosinec 2011. Čís. 3148 (speciální vydání Animal biodiversity: An outline of higher-level classification and survey of taxonomic richness, ISBN 978-1-86977-850-7, editor ZHI-QIANG ZHANG), s. 13-18. Dostupné online. PDF [1]. ISSN 1175-5334. (anglicky)
6. ↑ BioLib, kmen houbovci. Dostupné online

Externí odkazy

• Obrázky, zvuky či videa k tématu Houbovci ve Wikimedia Commons
• Encyklopedické heslo Houby v Ottově slovníku naučném ve Wikizdrojích
• http://paleo.cortland.edu/tutorial/Protista/porifera.htm
• http://www.ucmp.berkeley.edu/porifera/porifera.html

Gennemskåret svamp (Ceratoporella)

Havsvampe (Porifera) er en række af primitive flercellede hav- og ferskvandsdyr. De kaldes også dyriske svampe, spongier eller blot svampe.^[1] Havsvampe er fyldt med porrer og kanaler så der kan strømme vand gennem dem. De har intet nervesystem, fordøjelsessystem eller blodkredsløb. I stedet er de afhængige af konstant vandstrømning gennem deres kroppe for at få føde og ilt, samt fjerne affaldsstoffer.

Store tøndeførmede svampe - Xestospongia testudinaria.

Havsvampe kan have klump- eller krukkeform og mange lever i kolonier, som er forgrenede eller danner uregelmæssige overtræk på klipper og sten. De fleste indeholder et skelet af kalknåle, kiselnåle eller et hornagtigt protein (spongin). De sidstnævnte bruges i tørret tilstand som badesvampe.

Dyrernes ernæring består af organisk stof, der frafiltreres vandet. Filtrationen foregår ved at vandet ledes gennem fine kanaler, som findes overalt i havsvampenes legeme, til særlige filtrationskamre.

Havsvampe forefindes langs næsten alle danske kyster som et hvidt dyr, der oftest bliver skyllet på land sammen med tang, når det er dødt.

Klassifikation

Række: Porifera

• Underrække: Cellularia
  • Klasse: Demospongiae
  • Klasse: Calcarea
• Underrække: Symplasma
  • Klasse: Hexactinellida

Galleri

• Callyspongia vaginalis, i havet ud for Haiti

• Haliclona - formodentlig det blåhullede nederst?

Kilder

• Systema naturae 2000 (classification) – Taxon: Phylum Porifera
• http://allearter.dk/

Dieser Artikel beschreibt die wasserlebenden Tiere. Für andere Bedeutungen siehe Schwamm.

Die Schwämme (Porifera, lateinisch porus ‚Pore‘ und ferre ‚tragen‘) bilden einen Tierstamm innerhalb der vielzelligen Tiere (Metazoa). Sie leben allesamt im Wasser und kommen in allen Meeresgewässern der Erde vor. Nur wenige Arten leben im Süßwasser wie etwa ungewöhnlich große (bis mannsgroße) Exemplare im Staffelsee.

Es gibt über 8300 Arten (Stand: 2012)^[1] von 2 Millimetern bis über drei Meter Höhe. Die Gestalt der meisten Arten ist abhängig von Ernährung und Milieu. Im Gegensatz zu den Gewebetieren (Eumetazoa) haben Schwämme keine Organe sowie keine Neuronen zur Verarbeitung von Signalen.^[2] Sie leben sessil, bevorzugt auf Hartboden, können aber auch Überzüge auf Pflanzen oder Mollusken-Schalen bilden. Der überwiegende Teil der Schwämme ernährt sich durch Filtration.

Bedeutende fossile Schwämme sind die Stromatoporen, die im Paläozoikum (Erdaltertum), hier besonders im Devon, und Mesozoikum (Erdmittelalter) wichtige Riffbildner waren. Diejenige Richtung der speziellen Zoologie, die sich der Erforschung der Schwämme widmet, wird als Spongiologie bezeichnet.

Bau

Obwohl Schwämme aus verschiedenen spezialisierten Zellen aufgebaut sind, besitzen sie keine Muskel-, Nerven- und Sinneszellen. Der Schwammkörper kann in die folgenden drei Grundtypen von Zellen gegliedert werden:

Pinacocyten

Die Pinacocyten bilden die plattenförmige Deckschicht (Pinacoderm) der Schwämme aus. In der Deckschicht liegen die Ostien, kleine Poren, die der Wasseraufnahme dienen und das Wasser über ein Kanalsystem in den zentralen Hohlraum (Gastralraum, auch Spongocoel) führen.

Choanocyten

Bei den Choanozyten handelt es sich um Kragengeißelzellen, die durch das Schlagen einer Geißel einen Wasserstrom erzeugen, aus dem sie vor allem über den Mikrovilli-Kragen kleine Nahrungspartikel filtrieren. Kragengeißelzellen verdauen die Nahrung und geben Teile davon an andere Zellen weiter. Wenn diese gefüllt sind, wandeln sie sich in einfache Nährzellen um, dringen in die Mittelschicht und versorgen dort die anderen Zellen. Sie sitzen um innere Hohlräume (Geißelkammern) herum.

Amöbozyten

Amöbozyten (Amöboidzellen) sind Zellen, die bei den Schwämmen (Porifera) mit ihren beweglichen Scheinfüßchen (amöboid) im Körper herumwandern und z. B. die Nährstoffe verteilen, die sie von den Choanocyten erhalten oder in deren Nähe durch Phagozytose aufnehmen. Auch nehmen sie Botenstoffe auf, geben sie ab und erbringen damit Funktionen, die denen eines primitiven Nervensystems vergleichbar sind.

Die Amöboidzellen können unterschiedlich differenziert sein. Man findet:

• Amöbocyten, bei denen es sich um Verdauungs- und Nahrungsverteilungszellen handelt,
• Archaeocyten, aus denen alle anderen Zellen hervorgehen,
• Skleroblasten, skelettbildende Zellen, und
• Geschlechtszellen.

Die Amöboidzellen sind in ein kolloidales Gel, eine zellfreie Grundsubstanz, eingelagert. Im Gel bilden die Skleroblasten Skelettelemente, die Schwammnadeln aus.

Die Amöboidzellen, das kolloidale Gel, die Skelettelemente und die Pinacocyten wird als Dermallager (Derma = Haut) zusammengefasst. Die Gesamtheit der Choanocyten bezeichnet man als Gastrallager (gaster, d. h. ‚Magen‘).

Spicula eines Pachastrelliden

Skelettelemente

Das Skelett besteht aus Skleriten (auch Skleren als Mikro- oder Megaskleren genannt), sogenannten Spicula (lat. sing. spiculum; Pfeil, Nadel), die ein Produkt der Sklerocyten sind und entweder aus Calcit, einer Form von Calciumcarbonat (Kalkschwämme), oder Kieselsäure (Kieselschwämme) bestehen. Die Gestalt der Spicula ist für die Systematik rezenter und fossiler Schwämme von Bedeutung.

Bei den Hornkieselschwämmen (Demospongiae) spielt auch Spongin eine wichtige Rolle.

Skelettreste des Kieselschwammes sind teilweise in den sogenannten Klappersteinen enthalten.

Einteilung in drei Typen

Baupläne der Schwämme:
A. Ascon, B. Sycon, C. Leucon
1) Suboscularraum 2) Oscula
3) Radialtuben 4) Geißelkammern
5) 6) Poren

Je nach Ausbildung des Gastralraumes können drei Bautypen unterschieden werden:

Ascon-Typ

Schlauchförmiger, dünnwandiger Körper mit zentralem Hohlraum mit undifferenzierter Wandung und nur einer zentralen Ausströmöffnung (Osculum). Dieser Typ ist immer sehr klein, da das Verhältnis von Körperoberfläche zu Mesohyl sehr ungünstig ist (maximal 2 mm groß). Außen liegt das Epithel, innen befinden sich die Kragengeißelzellen.

Sycon-Typ

Um einen großen Hohlraum herum wird Choanoderm durch Radialtuben (in diesen befinden sich die Choanocyten) in das Mesohyl eingelagert, wodurch eine Oberflächenvergrößerung erreicht wird. Schwämme dieses Typs erreichen Größen von ein paar Zentimetern. Dickwandiger Körper, ausgekleidet mit Kragengeißelzellen.

Leucon-Typ

Der differenzierteste Bautyp, dessen Mesohyl von Geißelkammern durchsetzt (verzweigtes Kanalsystem mit kugelförmigen Kammern) und stark verdickt ist. Dadurch wird eine optimale Oberflächenvergrößerung realisiert. Diesen Typ weisen alle großen Schwämme auf. Der Körper ist sehr dickwandig.

Systematik

Der Stamm Porifera wird in drei oder vier Klassen unterteilt:

Klasse Calcarea (Kalkschwämme). Spicula mit 1, 3 oder 4 Strahlen aus Kalk (Calciumcarbonat), das in Form von Calcit auskristallisiert ist. Calcarea leben im Allgemeinen in flachen Küstengewässern.

Klasse Hexactinellida (Glasschwämme). Ca. 600 Arten. Drei- oder Sechsstrahlige Spicula oder davon ableitbare Nadelformen, die aus amorphem wasserhaltigem Siliziumdioxid (Kieselsäure) aufgebaut sind. Hexactinellida leben im Allgemeinen in größeren Tiefen, zwischen 450 und 900 m.

Klasse Demospongiae (Hornkieselschwämme). Ca. 5000 Arten. Die Spicula aus amorphem wasserhaltigem Siliziumdioxid sind Monoaxone oder Tetraexone, die durch ein Netz von Sponginfasern teilweise oder komplett ersetzt werden können. Die Demospongiae sind die größte und am weitesten verbreitete Gruppe der Porifera. Sie kommen in allen Tiefen vor. Alle kommerziell genutzten Schwämme sind Demospongiae.

Klasse Homoscleromorpha. Ca 120 Arten. Die Klasse Homoscleromorpha wird von manchen Autoren als Unterklasse der Demospongiae angesehen. Mittlerweile gilt sie aufgrund molekularer Daten als klar von diesen abgegrenzt. Sie wird auch als Schwestertaxon zu den Calcarea angesehen.^[3]

1970 wurde für eine Gruppe von Schwämmen die Klasse der Sclerospongiae eingerichtet, die aber ab den 90er Jahren meist wieder aufgegeben wurde. Sclerospongiae zeichnen sich durch ein massives Skelett aus Calciumcarbonat (Aragonit oder Calcit) aus, das nur von einer dünnen Schicht lebenden Gewebes überzogen ist, das Spicula aus Kieselsäure oder auch Sponginfasern enthalten kann. Die Arten der Sclerospongiae wurden den Demospongiae und Calcarea zugeordnet.

Ernährung

Archaeocyten, Amöbocyten, Choanocyten und auch Pinacocyten nehmen die im Wasser enthaltenen Nahrungspartikel durch Phagozytose auf. Sie ernähren sich durch Einstrudeln von Wasser, aus dem sie Nahrungspartikel herausfiltern. Die Kragengeißelzellen erzeugen durch das Schlagen der Geißeln im inneren Hohlraum einen Wasserstrom (wo die Nährstoffe aufgenommen werden). Das Wasser tritt durch die kleinen Einstromöffnungen, Ostia, ein und gelangt durch Kanäle in den inneren Hohlraum Gastralraum. Durch eine an der Oberseite der Tiere gelegene Pore, das Osculum, tritt das Wasser wieder aus.

Für Asbestopluma hypogea (Cladorhizidae) wurde eine karnivore Ernährung beschrieben. Der nährstoffarme Tiefseehöhlen bewohnende Schwamm hat sein Choanocyten-System verloren und fängt kleine Krebstiere mit Filamenten, die mit haken-ähnlichen Spicula besetzt sind. Die Beute wird dann von Amöbocyten verdaut.^[4]

Bisher waren 3 Arten vor Australien als fleischfressend bekannt. Vor der Ostküste Australiens wurden 2017 bei einer Tiefseeexpedition von Forschern des Queensland Museums mit Wissenschaftlern der Ludwig-Maximilians-Universität München überwiegend in einer Tiefe von 2000 bis 4000 m 17 weitere neue fleischfressende Schwammarten entdeckt und im Mai 2020 in Zootaxa beschrieben.^[5]

Physiologie

Trotz ihres einfachen zellulären Aufbaus ist die Physiologie der Schwämme komplexer, als lange Zeit angenommen. Schwämme sind in der Lage, Licht, mechanische Reize, Wasserströmungen und Sedimentablagerungen wahrzunehmen und aktiv darauf zu reagieren. Nicht nur ihre Larven, sondern auch Adulti einiger Arten sind zu (wenn auch langsamer) aktiver Fortbewegung in der Lage. Bei zahlreichen Arten wurde die Fähigkeit zu wellenartiger Kontraktion und anschließender Wiederausdehnung beobachtet, was vermutlich den Wasseraustausch im inneren Hohlraumsystem effizienter gestaltet. Die Bewegungen von Schwämmen gehen auf organisierte Bündel von Aktinfilamenten in bestimmten Pinacozyten zurück.^[6] Signalweiterleitung im Gewebe erfolgt sowohl chemisch als auch durch elektrische Aktionspotenziale (bisher nur bei einer Art sicher nachgewiesen). Bei Schwämmen sind zahlreiche Moleküle nachgewiesen, die bei den Eumetazoa als Neurotransmitter dienen wie Adrenalin, Noradrenalin und Serotonin. Obwohl also weder spezialisierte Nervenzellen noch Sinneszellen oder echte Muskelzellen vorzukommen scheinen, können Schwämme zahlreiche Funktionen dieser Zelltypen auf ähnliche Art und Weise wie bei den höheren Vielzellern ausführen.^[7]

Fortpflanzung und Entwicklung

Schwämme sind getrenntgeschlechtlich oder Zwitter, die sich geschlechtlich oder ungeschlechtlich vermehren können. Spermien entstehen in der Regel aus Choanocyten und Eizellen aus großen Archaeocyten. Bei der asexuellen Vermehrung kommt es zu einer Abschnürung von Zellverbänden an der Körperoberfläche, man spricht hier von Knospung, oder einem Verbleib der Zellverbände und somit einer Koloniebildung. Bei der sexuellen Vermehrung gibt es keine Geschlechtsorgane im eigentlichen Sinne. Die Spermien werden, nachdem sie ins Wasser abgesetzt wurden, von benachbarten Schwämmen in die Kragengeißelkammern eingestrudelt, von wo aus sie in das Mesohyl zu einer Eizelle transportiert werden. Aus der Eizelle entwickelt sich eine Larve, wobei verschiedene Larven-Typen vorkommen.

Die Larve der Kalkschwämme und der Homoscleromorpha (einer Unterklasse der Hornkieselschwämme) ist beispielsweise eine freischwimmende Blastula, die sich mit der Urmundregion festheftet und gastruliert.

Ist die Larve in einen vorderen, begeißelten Teil (späteres Entoderm) und einen unbegeißelten Teil (späteres Ektoderm) differenziert, spricht man von einer Parenchymula-Larve. Diese ähnelt der Planula der Nesseltiere (Cnidaria), unterscheidet sich jedoch von dieser dadurch, dass sie sich mit dem oralen Pol festsetzt und das Innengewebe im Gegensatz zur Planula die Außenschicht bildet.

Schwämme können ein sehr hohes Alter erreichen, beispielsweise ist der älteste bekannte noch lebende Schwamm der Art Anoxycalyx joubini mindestens 10.000 Jahre alt und zählt somit zu den ältesten Lebewesen unseres Planeten. Er lebt im Südpolarmeer und wurde dort mehrmals von Wissenschaftlern untersucht, die sein Alter anhand seines – sehr geringen – Sauerstoffverbrauchs ermittelt haben: Je weniger Sauerstoff ein Tier in Bezug auf seine Körpergröße benötigt, desto geringer sein Wachstum und umso älter ist es.

Dauerstadien

Viele limnische Schwämme haben die Fähigkeit, Überdauerungsstadien, sogenannte Gemmulae (Gemmula = kleine Knospe, auch Hibernakel), zu bilden. Diese bestehen aus dikaryonten (zweikernigen) Archaeocyten, welche von einer Schicht aus Spongin und besonderen Nadeln (Spicula) umhüllt werden. Es kommt aber auch im einfachsten Fall zur Bildung von Restkörpern (Reduktien). Auslöser für die Entwicklung dieser Dauerstadien sind schlechte Umweltbedingungen, wie zum Beispiel Nährstoffmangel, oder auch im Besonderen bei Süßwasserschwämmen der Wechsel der Jahreszeiten.

Wirtschaftliche Bedeutung

Badeschwamm

Die Skelette der Gruppe der Hornschwämme (Dictyoceratida) sind frei von Spicula (Nadeln) und bestehen aus einem Geflecht flexibler Sponginfasern. Durch einen Prozess, den man als Mazeration bezeichnet, wird das Zellmaterial aufgelöst und ausgespült. Das so gewonnene Sponginskelett eignet sich durch seine Saugfähigkeit sehr gut als Gebrauchsschwamm (Badeschwamm). Der künstlich hergestellte Reinigungsschwamm leitet seine Bezeichnung auf Grund seiner Eigenschaften und seiner Struktur von den Schwämmen ab.

Des Weiteren werden Schwämme heutzutage in Aquakulturen gezüchtet, um verschiedene chemische Substanzen aus ihnen zu gewinnen, die vor allem auch in der Medizin Anwendung finden.

Siehe auch

• Systematik des Tierreiches

Einzelnachweise

1. ↑ Phylum Porifera Grant, 1826. In: Zhang, Z.-Q. (Editor) Animal biodiversity: An outline of higher-level classification and survey of taxonomic richness. Zootaxa 3148: 1–237. „Living Porifera includes 4 classes, 25 orders, 138 families, 722 genera, and 8,346 species as of 8 December 2012; fossil taxa include 4 classes, 34 orders, 191 families and 1032 genera, with a presently unknown number of described species.“
2. ↑ L. Sherwood, H. Klandorf, P. Yancey: Animal Physiology: From Genes to Organisms. Cengage Learning, 2012, ISBN 978-1-133-70951-0, S. 150.
3. ↑ El-Bawab, Fatma: Invertebrate Embryology and Reproduction. 1. Auflage. 2020, ISBN 978-0-12-814114-4, Chapter 4 - Phylum Porifera, S. 106–169, doi:10.1016/C2016-0-04781-2.
4. ↑ J. Vacelet, N. Boury-Esnault: Carnivorous sponges. In: Nature. Band 373, 1995, S. 333–335, doi:10.1038/373333a0.
5. ↑ Große Anzahl fleischfressender Schwammarten entdeckt orf.at, 27. Mai 2020, abgerufen am 27. Mai 2020.
6. ↑ G. R. D. Elliott, S. P. Leys: Coordinated contractions effectively expel water from the aquiferous system of a freshwater sponge. In: Journal of Experimental Biology. Band 210, Nr. 21, November 2007, S. 3736–3748, doi:10.1242/jeb.003392.
7. ↑ Emanuelle Renard, Jean Vacelet, Eve Gazave, Pascal Lapébie, Carole Borchiellini, Alexander V. Ereskovsky: Origin of the neuro-sensory system: new and expected insights from sponges. In: Integrative Zoology. Band 4, Nr. 3, September 2009, S. 294, doi:10.1111/j.1749-4877.2009.00167.x.

Mga espongha, ang mga miyembro ng philum Porifera ay isang basal Metazoa clade bilang kapatid na babae ng Diploblast. Ang mga ito ay multiselular na organismo na may mga katawan na puno ng mga pores at mga kanal na nagpapahintulot sa tubig na magpakalat sa pamamagitan ng mga ito, na binubuo ng jelly-like mesohyl na sandwiched sa pagitan ng dalawang manipis na layer ng mga selula.

Ang lathalaing ito ay isang usbong. Makatutulong ka sa Wikipedia sa nito.

*

Koan-î pún tōng-bu̍t ka-kang he̍k-chiá jîn-chō ê châi-liāu, chhiáⁿ khòaⁿ hái-mî (châi-liāu).

Hái-mî sī chi̍t lūi tōng-bu̍t, Latin hō-miâ Porifera, hun-lūi-ha̍k siōng sī chi̍t-ê mn̂g, in-ê sin-thé ū khang kap kóng, chúi ē-sài ti̍t-chiap lâu kòe thé-lāi.

Las espongas constituisson l’embrancament (versemblablament parafiletic) dels Esponguiaris e son d'animals sens sistèma nerviós ni tube digestiu. Son còrs es format pas que per dos jaces de cellulas (ectodèrma e endodèrma).

• Membrana extèrna o ectodèrma : las cellulas epidermicas que compausan l’exodèrma son apeladas pinacocits e de porocits que son de cellulas cròias permetent lo passatge de l'aiga de vèrs l'interior de l'esponga.
• Membrana intèrna o endodèrma : es formada de cellulas de coleretas constituidas de choanocits. Aquestas cellulas son tanben flagelladas per assegurar una circulacion d’aiga e una retencion de noiridura.

Paret d'espongas (20 m de pregondor) (Croàcia)

• Portal de la zoologia

Porifera es un phylo de animal.

Ta faastguinyn, thoagyn ny marrey, ny Porifera, nyn phylum ‘sy reeriaght Animalia. Ta thoagyn cummal ‘syn ushtey, as t’ad ry-akin ayns dagh mooir y teihll. Cha nel agh beggan thoagyn cummal ayns ushtey millish.

Ta ny smoo na 7500 dooieyn ayn, eddyr beggan millimeadaryn as tree meadaryn ‘syn yrjid. Ta cummey as mooadys y thoag croghey er beaghey as çhymyllaght. Er y fa nagh vel organeyn erbee ec thoagyn, cha nel ad casley rish y chooid elley jeh Animalia. Ny yei shen, ta killaghyn oc currit da obbyr er lheh. Cha nel coryssyn neayrag, lheieagh ny cuishlagh oc. Ta thoagyn soit, er y thalloo son y chooid smoo, agh ny keayrtyn, er lossreeyn ny eeastyn shliggagh. Dy cadjin, ta thoagyn goaill bee liorish shollaney; t’ad sheelaghey ushtey trooid nyn gorpyn. Ta beggan jeu nyn eederyn foalley, as beggan elley, ta mynvioee oc as adsyn co-haaghey sollysh son y ghaa.

Imraaghyn

Porifera iku asalé saka tembung porus kang duwé arti bolongan cilik lan ferre kang tegesé duwé. Porifera iku kéwan kang duwé bolongan-bolongan cilik utawa kéwan kang duwé pori-pori. Porifera duwé saluran banyu kang ngatur sirkulasi banyu ing awaké. Rupané kéwan saka jinis iki rupa-rupa ana kang kaya piala, terompet, lan ana kang akèh pangé kaya tuwuhan.^[1] Awaké némpél ing dhasar banyu, ana kang ana warnané lan uga ana kang ora duwé warna.^[1] Porifera ora duwé organ pencernaan, sistem saraf, lan sistem perédharan getih.^[1] Sistem réprodhuksiné ana loro ya iku séksual lan aséksual.^[2] Lapisan kang nyusun awak Porifera saka jaba mara jero ya iku:

• Epidhérmis utawa lapisan kang paling jaba. Lapisan iki disusun saka pinakosit (sél epitelium pipih).^[1]
• Mesoglea(gelatin) lapisan iki dadi lapisan kanggo watesé sél epidhérmis lan lapisan éndhodhérmis.^[1] Lapisan iki dibagi manèh dadi loro, ya iku:
  • sél-sél ameboid, fungsiné sél iki kanggo ngangkud zat panganan lan zat luwihan metabolisme saka sél kang siji mara sel liyané^[1]
  • sel skleroblas, fungsiné kanggo gawé spikula.^[1] Spikula iku ri kang fungsiné kanggo nguataké sel dhinhing kang amoh.^[1] Spikula rupané rupa-rupa kang komposisiné saka zat kapur, zat kersik, lan ana uga spongin kang saka protéin.^[1]
• Éndhodhérmis utawa lapisan jero, lapisan iki saka koanosit kang duwé flagela lan fungsiné kanggo mencerna panganan.^[1]

Cathetan suku

Un sponja de la jenera Aplisino

Sponjes, la membros de la filo Porifero ("por porta") es un clado basal de animales e la sore la plu prosima de la diploblastos. Los es organismes multiselulal cual ave corpos plen de pores e canales cual permete ce acua sirculi tra los, composada de mesohil, un materia jelatin, entre du stratos magre de selulas.

Sponjes ave selulas nonspesialida cual pote muta a otra tipos e cual migra comun entre la stratos e la mesohil en la prosede. Sponjes no ave sistemes de nervos, dijesta, o sirculi. En loca, la plu depende de la manteni de un flue constante de acua tra sua corpos per oteni nuri e oxijen e per desprende dejeta. Sponjes ia es la ramo prima cual diverje de la arbor de evolui de la antesedente comun de tota animales, e donce los pte es videda como la sores de tota otra animales.

Puqyala (Porifera) nisqakunaqa ancha sikllalla, llamp'u, t'uqusapa, mana kuyuq, yakupi kawsaq, ch'ulla kawsaykuqkunata muyurispa mikhuq, mana chiqap kawsaykuq tantalliyuq uywakunam.

D'Schwämm (Porifera) sinn e Stamm bannent dem Déiereräich. Et gëtt ëm déi 5.000 bekannt Aarten.

Liewensraum

Kierperbau

D'Schwämm si primitiv Déieren, déi spezialiséiert Zellen, awer keng Organer hunn. Duerch déi baussent Zellschicht, hir Poren, stréimt d'Waasser mat der Nahrung, vun Zellen transportéiert duerch d'Déier a verléisst de Kierper duerch eng Ëffnung erëm.

Liewensweis

Schwämm sinn einfach villzelleg Déieren ouni richtegt Gewief, déi hir Nahrung aus dem Waasser filteren.

Um Spaweck

Sfungjerët janë gjallesa shumëqelizore me ndërtim të thjeshtë. Ato jetojnë në ambiente me ujë (në ujërat e deteve,liqeneve dhe lumenjëve) të përforcuara për substrat. Përfaqsues të sfungjerëve e marrim sfungjerin e zakonshëm, i cili është banor i përhershëm i Detit Adriatik.

Trupi i sfungjerit të zakonshëm është në formë të një qeske me grykë lart,jeton në koloni. Trupi i tij është i përbërë prej dy shtresave nga e jashtmja dhe e brendshmja. Në shtresën e jashtme ndodhen qeliza në formë pak a shumë të shtypura,ndërsa në shtresën e brendshme janë të pranishme qelizat e pajisura me nga një kamxhik.

Në sipërfaqe të trupit të sfungjerit ndodhen vrima të shumta, të cilat me anë të kanaleve lidhen me zgavrën e trupit.Së bashku me ujin futen edhe grimcat e vogla të ushqimit, me të cilat ai ushqehet. Uji pas qarkullimit nëpër trup del nga vrima që ndodhet në majë të trupit. Sfungjerin e zakonshëm e karakterizon edhe procesi i ripërtëritjes. Sfungjeri i zakonshëm shumohet me anë të bulave. Por ato shumohen edhe në mënyrë seksuale.

Sfungjerët janë shtazë shumëqelizore më primitive, të cilat kanë origjinë prej shtazëve njëqelizore-kamxhikorëve. Këtë tregon edhe fakti se në trupin e sfungjerëve ka qeliza me kamxhikë.

Muundo wa sifongo-bahari; njano: pinakositi, nyekundu: koanositi, kijivu: mesohili, samawati: mtiririko wa maji.

Sifongo-bahari ni wanyama sahili wa maji (bahari na baridi) katika faila Porifera (maana: walio na vinyweleo) ambao wamekazika chini, ijapokuwa spishi chache zinaweza kwenda kwa mbio wa mm 1-4 kwa siku. Spishi nyingi sana zina umbo wa yai, bonge au bomba. Kuna kipenyo kikubwa kiasi juu yao (osculum au kidomo) na vinyweleo vidogo vingi (ostia) kila sehemu ya mwili.

Mwili wa sifongo ni ukuta wa seli tu ambao unazunguka uwazi wa katikati. Ukuta huu umeumbwa kwa tabaka la kolajini (collagen) au mesohili (mesohyl) lililofunikwa na seli nje na ndani. Hata vinyweleo vimezungukwa na seli zinazoitwa porositi (porocytes). Seli zenye kijeledi (flagellum), ambazo huitwa koanositi (choanocytes), zisukuma maji kuelekea osculum na maji mengine yaingia kupitia ostia. Chembe za kulika zilizomo majini ziliwa kwa phagocytosis.

Picha

• Clathrina coriacea (Calcarea)

• Aphrocallistes beatrix (Hexactinellida)

• Callyspongia vaginalis (Demospongiae)

• Oscarella lobularis (Homoscleromorpha)

Wasomaji wanaombwa kuchangia mawazo yao kwenye ukurasa wa majadiliano ya makala.
Kamusi za Kiswahili hazina jina kwa mnyama huyu au wanyama hawa.

De spoensn (porifera), (Latyn: porus, porie, en ferre, droagn), zyn e stamme van primitieve, mêercellige bêestn die under nie kunn vôortbeweegn. Ze leevn in 't woater en ze zettn under vaste ip de bodem. De mêeste leevn in zêen en oceoann, toet ip 8,5 kilometer diepe, moa der zyn ook zoetwoaterspoensn. Ze vangn under eetn deur woater te filtreern. Z' èn gin aparte orgoann, spiern of zenuwn. Der zyn e goeie 8400 sôortn bekend, en regelmoatig wordn der nieuwe sôortn beschreevn. Spoensn zyn van d' oudste bekende bêestn. Fossieln dateern van 't Precambrium.

Bouw

Spoensn èn e simpeln bouw. Ze bestoan uut e buuze, woavan dat er êen ende vastegezet is ip de bodem. 't Boovnste ende van de buuze is oopn en wordt osculum genoemd. Vanbinn ist er een holte, 't spongocoel. De buuze èt e skelet die mêestal ipgebouwd is uut skeletnoaldn (spicula). Deur de wand van de buuze wordt woater noa binn gezoogn en via de boovnkant, 't osculum, komt 't were noa buutn.

Spoensn èn mor e poar sôortn celln:

• Kroagcelln (choanocytn), die an de binnkant van de buuze zittn en die 't eetn verteirn.
• Sluutcelln (porocytn), buusvormige celln die buuzn vormn deur de wand van de spoense. Doadeure kan woater noa binn stroomn.
• Contractiele celln, die de poriën ênigszins kunn toedrukkn, woadeure dat de stroomienge vermindert.
• Dekcelln (pinacocytn), an de buutnkant van de buuze, die gezoamelyk 't "vel" vormn.
• Amoebocytn, celln die in de wand leevn en zorgn vo transport van voediengsstoffn tusschn binn en buutnkant, d' ipbouw van de skeletnoaldn en de produucsje van vôortplantiengscelln.
• Archeocytn, oengedifferentieerde celln die oender andere kunn uutgroein toet eicelln.

In zekere zin kan e spoense ook anzien wordn lyk e kolonie van celln en nie lyk een individu. Os de celln van e spoense byvoorbeeld deur e mixer g'hoald wordn, goan de celln mekoar weere ipzoekn en e spoense vormn.

Vôortplantienge

Oengeslachtelyk

Spoensn èn e grôot regeneroasjevermeugn. Iedere celle èt de meugelykheid van uut te groein toet e nieuwe spoense. An de buutnkant van de spoense kunn knoppn wordn gevormd, die losloatn of ofbreekn en ton uutgroein toet e nieuwe spoense. An de binnkant van de spoense kunn gemmulae oentwikkeln. E gemmula bevat vele kroagcelln (choanocytn) en is omgeevn deur skeletnoaldn. Ze kunn uutdroogienge en bevriezienge overleevn. Ze kommn geweunlyk vry os de spoense dôodgoat en by gunstige omstandigheedn goan z' oopn en vormn nieuwe exemploarn.

Geslachtelyk

Spoensn zyn mêestal hermafrodiet (twêeslachtig), of wisselnd mannelyk en vrouwelyk. Vôortplantiengcelln kunn oentstoan uut al de sôortn celln, moa spermacelln oentstoan mêestal uut kroagcelln en eicelln uut archeocytn. De spermacelln kommn de vrouwelyke spoense binn met de woaterstroom deur de buuze van de spoense. Bevruchte eicelln oentwikkeln under toet vryzwemmnde larvn. In sommigte gevalln bluuft de larve e tyd in de moederspoense. Uutendelyk vestign de larvn under ip de bodem en groein uut toet e nieuwe spoense.

Classificoasje

Volgns World Register of Marine Species (1 moarte 2016) zyn der vier klassn spoensn die nog in leevn zyn:

• Klasse Calcarea (Kalkspoensn)
• Klasse Demospongiae (Geweune spoensn)
• Klasse Hexactinellida (Glasspoensn)
• Klasse Homoscleromorpha

Uutgestorvn:

• Archaeocyatha. Uutgestorvn in 't Cambrium
• Otavia antiqua. Fossiel gevoendn van 760 miljoen joar oud

Videz anke Sponjo (homonimo)

Sponjo esas animalo (preske celuli-kolonio) di brancho Porifera.

Esas primitiva maxim simpla, nemovinta, precipua marala, nutriva per filtrado.

Sponges are not ainimals o the phylum Porifera (meanin "pore bearer"). Thay are multicellular organisms that hae bodies full o pores an channels allaeing watter tae circulate throu them, consistin o jelly-lik mesohyl sandwiched atween twa thin layers o cells.

• 1 Indeiling
• 2 Bouw
  • 2.1 Basisbouw
  • 2.2 Gespecialiseerde celle en structure
  • 2.3 Versjèlle oonderein
  • 2.4 Versjèlle mèt de Radiata
• 3 Ecologie
  • 3.1 Woengebeed
  • 3.2 Voortplanting en levescyclus
  • 3.3 Natuurleke vijande en verdeideging
• 4 Gebruuk
• 5 Bron

Spužva iz Papua Nove Gvineje.

Porifera – spužve ili sunđeri – su vodeni organizni dimenzija od 1 cm do 1m. Žive u moru osim jedne porodice (Spongilidae) koja živi u vodama na kopnu. Ovo su najjednostavnije metazoea. Ćelije im ne mogu funkcionisati samostalno već samo usaglašeno iako se mogu iskidati i da od svakog iskidanog dijela nastane nova jedinka. Zbog ove osobine smatraju se jednostavnim metazoama. Tijelo im je specifično građeno. Pričvršćeni su za podlogu i hrane se pasivno. Mlade jedinke žive samostalno, pupaju i tako nastaju kolonije. Najprimitivnije vrste su i najsitnije vrste Rast i oblik spužve uslovljeni su prirodnom podloge za koju se spužva prihvata i brzinom strujanja vode i talasima.^[1][2]

Pregled

• Na osnovu prirode skeleta, spužve se dijele na klase:

Protok vode

Spongia officinalis
Dok je živa, običma „kuhinjska spužva“ je tamno-siva

U spužvu voda ulazi kroz pore koje su raspoređene od spoljašnje do unutrašnje površine. Protok vode održavaju pokreti bičeva ćelija hoanocita. One propuštaju hranljive materije iz vode do ameboidnih ćelija koje ih sprovode do svih dijelova spužve. Hrane se živim i mrtvim organizmima suspendovanim u vodi. To su sitni planktonski organizmi, dijatomeje, bakterije, rastvorene organske materije, tjelešca simbiotskih organizama ili produkti njihove aktivnosti. Mnogi raci, kolutičavci, larve insekata i druge životinje služe spužvama kao zaklon. Strujanje vode snabdjeva spužvu kiseonikom i uklanja otpatke i ugljen dioksid

Većina spužvi je amoniotelična. Stvara razgradnjom azotne spojeve u obliku amonijaka, kao produkt ekskretorne djelatnosti. Osim amonijaka mogu se u malim količinama ustanoviti i mokrača i mokraćna kiselina.

Razmnožavanje

Djelomično su dvopolni, a djelomično razdvojenih polova (gonohoristi).

Spolno

Polne ćelije nastaju od posebno ameboidnih ćelija. Jedinka stvara jajne ćelije i spermatozoide, tj. oni su hermafroditi . Zrele spermatozoide izbacuju napolje kroz oskulum, voda ih prenosi i unosi u druge jedinke gdje se spajaju sa jajnim ćelijama. Iz zigota nastaje larva koja pliva, pada na dno i formira spužvu.

Bespolno

Odvija se pupljenjem,rijetko kad se odvajaju pupoljci. Oni ostaju uz majku i grade koloniju. Slatkovodni u jesen stvaraju gemule, koje su građene od embrionalne ćelije. Obavijene su sa dvije membrane. Spužva ugiba, a u proljeće iz pupoljaka nastaju nove jedinke.

Evolucija

Arheociatide, od kojih su neke klasificirane kao koralne spužve, bile su uobičajena pojava u kambrijskom periodu prije oko 530 miliona godina, ali su izumrne na njegovom kraju, prije oko 490 miliona godina.

Hoanoflagelata

U 1990.-im, spužve su naširoko smatrane monofiletiskom grupom; drugim riječima, da su sve potekle od zajedničkog pretka koji je sam po sebi spužva, i kao "sestrinska-grupa" za sve ostale metazoa (multi-jednoćelijska životinje), koje i same formiraju monofiletsku grupu. S druge strane, neke analize iz 1990-ih i oživjele su ideju da su višećelijskim životinjama najbliži evolucijski rođaci hoanoflagelate, jednoćelijski organizmi vrlo slična spužvama "hoanocite - što bi značilo da je većina Metazoa evoluirala od samih spužvi - i zato spužve možda neće biti monofiletska skupina. Spužvoliki preci možda su doveli i do modernih spužvi i spužve nisu članovi Metazoa.

Analize od 2001. godine su zaključile da su Eumetazoa (složeniji od spužvi) uže vezane za pojedine grupe spužvi nego za ostale. Takvp zaključci znače da spužve nisu monofiletske, jer bi posljednji zajednički predak svih spužvi bio direktni predak Eumetazoa, koje nisu spužve. Studija je 2001., na osnovu usporedbe ribosoma i DNK, ustanovila da je većina spužvi podjeljena između staklastih spužvi i ostalih i da su Eumetazoa uže povezane sa krečnjačkim spužvama sa kalcij karbonatnim spikulama, nego sa drugim vrstama spužvi. U 2007., jedna analiza, na osnovu usporedbe RNK, a uglavnom bazirana na poređenju spikula je pokazača da su demospongoje i staklaste spužve uže međusobno povezane nego sa krečnjačkim spužvama, koje su usko povezane sa Eumetazoa.

Ctenophora (češljasta meduza)

Ostali anatomskih i biohemijski dokazi povezuju Eumetazoa sa Homoscleromorpha, pod-grupom demospongija. Poređenje u 2007. godini nuklearne DNK, isključujući staklaste spužve i češljaste meduze, zaključuje da su:

• Homoscleromorpha najuže povezane sa Eumetazoa;
• krečnjačke spužve su sljedeće najbliže;
• s druge demospongije su evolucijske "tetke" ovih grupa; i

Chancelloriidae, torbaste životinje čiji su fosili nađeni u kambrijskim stijenama, mogu biti spužve.

Analize gore opisanih podatak pokazuje da spužve su najbliži preci svih Metazoa, drugim riječima svih multi-jednoćelijskih životinja, uključujući i spužve i složenije grupae. Međutim, još jedan poređenje u 2008. godini sa 150 gena u svakom od 21 roda, u rasponu od gljiva do ljudi, ali uključujući i samo dvije vrste spužvi, sugerira da suCtenophora najviše bazne loze Metazoa, koje su uključene u uzorak. Ako je to tačno, ili su se moderne češljaste meduze razvili svoje složene strukture nezavisno od drugih Metazoa, ili su preci spužvi bili složeniji, a sve poznate spužve su drastično pojednostavljeni oblici. Studija dalje preporučuje analize koristeći širi spektar spužvi i druge jednostavne Metazoa kao što su Placozoa. Rezultati takve analize, objavljeni 2009. godine, ukazuju na to da se može opravdano uvažiti prethodni prikaz. 'Porodično stablo' koje je izgrađeno kombinacijom svih raspoloživih podataka - morfoloških, razvojnih i molekulskih - zsugerira da su spužve zapravo monofiletska grupa, a sa cnidariama čine sestrinsku grupa bilateralnih organizama.

Klasifikacija

Podjela se vrši uglavnom prema gradi skeleta.

Krečnjački: Calcarea

Skelet im je od kalcijum karbonata. Uglavnom su malih dimenzija do 10 cm. Žive u moru i to u plićaku.

Staklasto-silikatni: Hexactinellida

Tijelo im je prožeto silikatskim iglicama koje liče na staklene niti. Srastaju u neprekidnu rešetku. Žive na dubini od 100– 5000 m. Ovoj grupi pripada Venerina korpica ( Eupactella aspergillum), Hyalonema sieboldi nađena je u moru blizu Japana.

Silikatsko rožast: Demospongia

Imaju skelet od silkatskih iglica ili rožnaste materije, nekad i od obje . Među njima je obična spužva Spongia officinalis , Neptunov pehar – Poterion Neptuni, veličine do 2 m u prečniku. Slatkovodna spužva Spongilla lacustiv je zelena zbog prisustva algi koje nastanjuju njeno tijelo.

Ekologija

Spužve pripadaju višećelijskim beskičmenjačkim životinjama, ali nisu pravi višećelijski organizmi jer nemaju tkiva i organe. Sastoje se od ćelija koje su u visokom stepenu nezavisne što se može dokazati vrlo jednostavnim eksperimentom. Tijelo spužvi se propusti kroz najfinije sito od svile čime se doslovno razdvoji na pojedinačne ćelije. Ako se tako isjeckana spužva vrati u prirodnu sredinu, pojedinačne ćelije će se nakon oko tri sedmice ponovo udružiti u cjelovitu jedinku. Upravo je dokazano da ćelije mogu opstati potpuno neovisno jedna od druge. Ni jedna druga životinja ne bi preživjela ovakavo surovo komadanje.

Veoma dugo su spužve, zbog svog sesilnog načina života, smatrani biljkama. Dodatnu zabunu unosi i njihova jarka obojenost, sa crvenom, narandžastom i žutom kao preovlađujućim bojama. Neke spužve (npr. u Bajkalskom jezeru) su čak i zeleno obojeni, samo što ta boja ne potiče od njihovog pigmenta već od pigmenta jednoćelijskih algi koje žive sa njima u simbiozi. Savremeni biolozi su i danas zbunjeni prisustvom pigmenata u tijelu spužvi koji žive uglavnom u uslovima tame, a poznato je da se funkcija pigmenata vezuje za svjetlost.

Također pogledajte

• Metazoa
• Životinja

Reference

A swaampen (Porifera) san en stam faan diarten an lewe uun't weeder, a miasten uun saaltweeder. Diar jaft at wel 7.500 slacher faan. Jo san tesken 3 mm an 3 m grat.

Iindialang

• Klas: Calcarea
• Klas: Demospongiae
• Klas: Hexactinellida
• Klas: Homoscleromorpha

Apbau

Di apbau faan swaampen skeelt efter trii münstern:

A. Ascon-münster

B. Sycon-münster

C. Leucon-münster

De Swammdeerter (Porifera, vun lat.: porus ‚Pore‘ un ferre ‚dregen‘) sünd Deerter, de en Stamm mank de Veelzellers (Metazoa) billen doot. Se dröövt nich dör'nanner kregen weern mit de Swämme, de nich to de Deerter rekent weert, man en egen Riek blangen de Deerter un de Planten billt. To'n Unnerscheed weert de Porifera vundeswegen hier Swammdeerter nömmt, gegen de Fungi over, de man bloß Swämme heet. Swammdeerter leevt alltohopen in’t Water un kaamt in all Saltwater-Seen up’e Eer vor. Bloß man en poor Aarden leevt in’t Söötwater. Dat gifft mehr, as 7.500 Aarden. Se weert vun en poor Millimeter bit hen to dree Meter hooch. Wie se utseht, dat hangt af vun ehr Freten un de Umwelt, wo se in leven doot. Anners, as de Geweevdeerter (Eumetazoa) hefft Swämme keen Organe. Se sitt up’n Grund fast, sunnerlich up harten Grund, man se könnt ok up Planten oder up Schillen vun Mollusken sitten. De meisten Swammdeerter kriegt ehr Freten dör Utfiltern ut’n Water.

Wichtige Swammdeerter ut de fossile Tied sünd de Stromatoporen. Se hefft in dat Paläozoikum, sunnerlich in’t Devon un Mesozoikum mit den Grund leggt for allerhand Riffs. De Twieg vun de Spezielle Zoologie, de sik mit Swammdeerter befaten deit, warrt Spongiologie nömmt.

Wie de Swammdeerter upboot sünd

Ofschoonst Swammdeerter ut allerhand Zellen mit je sunnerliche Upgaven tohopensett sünd, hefft se keen Muskel-, Nerven- un Sinnzellen. Dat Lief vun en Swammdeert kann in dree Grundtypen vun Zellen updeelt weern, dat sünd:

Pinacocyten

De Pinacocyten formt de Deckschicht (Pinacoderm) vun de Swammdeerter. In düsse Deckschicht liggt de Ostien, dat sünd lüttje Poren, de Water upnehmen könnt. Dat Water warrt denn over en Kanalsystem bit in den hollen Ruum (Gastralruum, ok Spongocoel) in de Midden vun dat Swammdeert spöölt.

Choanocyten

Bi de Choanozyten hannelt sik dat um Kragenpietschenzellen. Se slaht mit en Pietschen un kriegt so en Waterstroom in Gang. Dor filtert se denn, sunnerlich over den Mikrovilli-Kragen, lüttje Partikels to’n Freten rut. Kragenpietschenzellen verdaut dat Freten sülms un geevt dor de annern Zellen wat vun af. Wenn se vullfreten sünd, wannelt se sik in eenfache Nehrzellen um, wannert in de Middelschicht in un versorgt dor de annern Zellen. Se sitt binnen in de Deerter um holle Kamern (Pietschenkamern) umto.

Amoebocyten

Amoebocyten (Amöboidzellen) sünd Zellen, de mit ehre lüttjen Schienföte (amöboid) in dat Lief vun de Swammdeerter rumwannert. Dor verdeelt se u. a. de Nehrstoffe, de se vun de Choanocyten kregen hefft oder de se vun de Choanocyten upnehmen doot dör Phagozytose.

De Amöboidzellen könnt unnerscheedliche Upgaven heben: Dat gifft:

• Amöbocyten, de dat Freten verdeelt un verdaut.
• Archaeocyten, de all annern Zellen boen doot,
• Skleroblasten, de dat Skelett tostanne bringt un
• Geslechtszellen.

De Amöboidzellen sünd inlagert in en Gel, dat is en Grundsubstanz ohn Zellen. In düt Gel billt de Sklerolasten „Swammnadeln“ ut, dat sünd Skelettelemente.

De Amöboidzellen, tohopen mit dat Gel, de Skelettelemente un de Pinacocyten weert tohopenfaat as „Dermalager“ (Derma = Huut). De Choanocyten weert all tohopenfaat as „Gastrallager“ (Gaster = de Maag).

Spicula (Swammnadel) vun en Pachastrelliden

Weblenken

. Mehr Biller, Videos oder Audiodateien to’t Thema gifft dat bi Wikimedia Commons.

Σπόγγος

Γενικά με τον όρο σπόγγος χαρακτηρίζεται κάθε στερεή πορώδης μάζα με μεγάλη σχετική απορροφητική ικανότητα που σχηματίζεται κυρίως από θαλάσσιο ζωόφυτο και που χρησιμοποιείται σε διάφορες χρήσεις, φαρμακευτική, οικιακή, ατομική καθαριότητα κτλ. Πρόκειται για το κοινώς λεγόμενο σφουγγάρι. Σήμερα αντί του φυσικού σπόγγου χρησιμοποιούνται ευρύτερα τεχνικές πλαστικές απομιμήσεις περισσότερο οικονομικές.

Φυσικός σπόγγος

Ο φυσικός σπόγγος (λατ. Euspongia) ανήκει στο γένος των κοιλεντερωτών ζώων της οικογένειας των σπογγοιδών που απαντώνται σε διάφορες θάλασσες ειδικά με χλιαρά ύδατα και θαλάσσια ρεύματα ήπια, σε διάφορα βάθη. Για την οργανική σύσταση και κατάταξη των σπόγγων οι διχογνωμίες ξεκινούν από την αρχαιότητα. Ο Αριστοτέλης ήταν ο πρώτος που διαπίστωσε ύπαρξη ζωικής αίσθησης, κατατάσσοντάς τους στα ζώα. Με τη γνώμη του συντάχθηκαν ο Πλίνιος και ο Αιλιανός. Οι μεταγενέστεροι όμως φυσιοδίφες μεταξύ των οποίων οι Έρασμος, Ροντελέ, Τουρνεφόρ, Μαρσιλύ καθώς και αυτός ο Λινναίος στην αρχή υποστήριζαν ότι οι σπόγγοι ανήκουν στο φυτικό βασίλειο. Ο δε Μπορύ ντε Σαν Βενσάν δημιούργησε την κατάταξη «ζωόφυτα». Ο δε Παλλάς αργότερα υποστήριξε πως οι σπόγγοι ανήκουν σε πολύ κατώτατη ζωολογική βαθμίδα από άποψη οργανισμού, ενώ ο Γκραντ και άλλοι της εποχής του κατέδειξαν ότι ναι μεν ανήκουν σε κατώτατη βαθμίδα πλην όμως ζωική. Τέλος ο Λαμουαί, περισσότερο εκ του ασφαλούς, κατέταξε τους σπόγγους στη κατηγορία των «σπογγωδών», ενώ ο Ζωρζ Κυβιέ στη κατηγορία των «πολυπόδων». Tο 1940 η Cyman απέδειξε την αποικιακή μορφή τους και το 1967 ο Brien, βάσει της δομής και του τρόπου ανάπτυξής τους, τους τοποθέτησε οριστικά στα Mετάζωα .

Tα εμπορικά είδη των σπόγγων,που συναντώνται στο Aιγαίο και στον ευρύτερο μεσογειακό χώρο είναι:

• Hippospongia communis (Lamark, 1813) ή Kαπάδικο. Σφουγγάρι σχεδόν σφαιρικό. H κάτω επιφάνειά του είναι τραχιά και με αυτή προσφύεται στο υποστρωμα. Tο χρώμα του είναι σκούρο καφέ και αλιεύεται σε βάθη απο 9 έως 80 μ. Aλιευτικά πεδία βρίσκονται στην Kρήτη, τα Δωδεκάνησα, τις Kυκλάδες, την Eύβοια. Σε αυτό το είδος ανήκει και ο λεγόμενος «Δροσίτης». Πρόκειται για ένα Kαπάδικο,το οποίο ζει σε θαλασσινές σπηλιές και το χρώμα του είναι ανοιχτό καστανό.

• Spongia officinalis (Linaeaus,1759) adiatica (Schmidt, 1862). Λέγεται και «ματαπάς», όταν προέρχεται από μικρά βάθη, ή «φίνο» ή ελληνικός σπόγγος μπάνιου. Tο είδος αυτό χαρακτηρίζεται απο μεγάλη ποικιλομορφία. Tο χρώμα του μεταβάλλεται αντιστρόφως ανάλογα προς τη θολεροτητα. Eίναι σφουγγάρι ιδιαίτερα συμπαγές, ελαστικό και εύκαμπτο. Xαρακτηριστικο του γνώρισμα η αίσθηση του βελούδου που δημιουργεί η πολύ λεπτή του υφή. Tο βρίσκουμε στην Kρήτη, τα Δωδεκάνησα, τη Σάμο, την Eύβοια και σε βάθη μέχρι 100 μ.

• Spongia officinalis (Linaeus,1759) mollissima (Schmidt, 1862).Λέγεται και «μεθάλη» ή «τούρκικο φλιτζάνι» ή «λεπτός σπόγγος της Συρίας». Tο σχήμα του θυμίζει χωνί ή φλιτζάνι, ζει σε βυθούς με χονδροκοκκη άμμο, μεγάλα βράχια ή σε λιβάδια Ποσειδώνιας και σε βάθος 50 μ. περίπου.

• Spongia agaricina (Pallas,1766) ή Spongia officinalis lamella (Scchulze, 1862). Oι σφουγγαράδες το λένε «λαγόφυτο» ή «ψαθούρι» ή «λαφίνα» ή «αυτί ελέφαντα». Tο σφουγγάρι αυτό είναι από τα πιο όμορφα ανάμεσα στα άγρια και τα ήμερα. Tο σχήμα του μεταβάλλεται ανάλογα με την ηλικία του, ενώ οι νεαρές μορφές μοιάζουν με κύπελλο οπως και η «μελάθη». Όμως κατά την ενήλικη φάση της ζωής του το σχήμα αλλάζει τελείως, γίνεται ελασματοειδές και θυμίζει βεντάλια. Tο χρώμα του, όταν αλιεύεται από μεγάλα βάθη είναι γκρίζο–μπλε και η διάμετρος του μπορεί να ξεπεράσει το 1 μ. Προτιμάει τα σκληρά, κοραλλιογενή υποστρώματα και συνήθως συναντάται σε βάθη 60–100 μ. περίπου.

• Spongia zimoca (Schmidt,1862). Πρόκειται για τη γνωστή «τσιμούχα» ή «δερματώδης σπόγγος». H τσιμούχα παρουσιάζεται με πολλές μορφές και οι σφουγγαράδες λένε πως καμιά τσιμούχα δεν έχει όμοιά της. Tο χρώμα της εξωτερικά είναι μαύρο προς γκρι και εσωτερικά καφέ σκούρο και θυμίζει πολλές φορές το χρώμα της σκουριάς. Προτιμά τα σκληρά υποστρώματα και η συνοδός βιοκοινωνία είναι κοραλλιογενής. Tα βάθη που αλιεύεται κυμαίνονται απο 25 έως 100 μ. Aλιευτικά πεδία υπάρχουν στην Kρήτη, τα Δωδεκάνησα και τις Κυκλάδες.

Сунѓерите (лат. Porifera) се наједноставно градените многуклеточни животни (Metazoa). Тоа се бесткивни метазои коишто живеат во водена средина. Нивното тело е составено од голем број на клетки кои вршат одредена функција. Тие се расфрлани низ целото тело на сунѓерот, и не се групирани како кај ткивните животни, при што секоја клетка одделно си врши своја функција.

Спикули од скелет на сунѓер.

Сунѓерите на целата своја телесна површина имаат отвори, а во внатрешноста е развиен систем од канали и празнини. Во зависност на сложеноста на организацијата на телото, се разликуваат неколку типови на сунѓери:

• Сунѓери од аскон тип - Овој тип на сунѓер е изграден од два слоја на клетки: надворешен слој од сплескан епителијален ектодерм и внатрешен слој од издолжени клетки со камшик и огрличка (хоаноцити) - ендодерм. Помеѓу овие два слоја, има тенок слој од бесструктурна мезоглеа со пивтиеста градба и со расфрлани ов неа (разновидни по форма и функција) клетки. Во внатрешноста на телото има парагастрална празнина, која е во врска со надворешната средина со мали површински отвори и со еден поголем отвор - оскулум. Од аскон тип на градба се малку сунѓери.

• Сунѓери од сикон тип - Повеќето сунѓери се од овој тип. Имаат задебелена мезоглеа и посложен систем од канали и празнини.

• Сунѓери од левкон тип - Сунѓерите со најсложен тип на градба се наречени вака.

Особини на сунѓерите

Мезохил

Пинакоцит

Хоаноцит

Лофоцит

Пороцит

Ооцит

Археоцит

Склероцит

Спикула

Проток на вода

Главни видови на клетки кај сунѓерите^[1]

Сунѓерите, со мал исклучок, се морски животни кои водат седентарен начин на живот. Големината на телото варира од центиметар до над метар, а формата на телото е гранеста, пехареста или топчеста. Живеат поединечно или колонијално, но ваквата поделба е условна.

Познати се околу 5.000 видови сунѓери. Меѓу најпросто градените е морскиот варовников сунѓер од Sycon тип, долг 1-3 cm, висок, со радијална симетрија и оскулум, опкружен со сноп од варовнички игли. Меѓу стаклестите сунѓери (од кои се добива стаклена волна), најпознати се видовите од еуплектела (Euplectella), распространети во океаните. Во копнените води на Македонија се среќаваат Spongilla lacustris со космополитско распространување, а охридскиот сунѓер (Ochridospongia rotunda) е реликт и ендемик за Охридското Езеро.

За сунѓерите се смета дека постанале од праживотните, и тоа од колонијата на некои камшикари со огрличка, кои еволуирале во посебен правец, така што во натамошната еволуција од нив не се развила друга животинска група.

Наводи

সমুদ্ৰৰ ৬০ মি গভীৰ পানীৰ তলৰ শিলৰ দেৱালত লাগি থকা স্পঞ্জ

পৰিফেৰা (ইংৰাজী: :Porifera) যাৰ সাধাৰণ নাম স্পঞ্জ (ইংৰাজী: :Sponge) হৈছে এবিধ বহুকোষী প্ৰাণী। স্পঞ্জ বা পৰিফেৰা হৈছে প্ৰাণী ৰাজ্যৰ এটা পৰ্ব (phylum)। ইহঁত সাধাৰণতে সামুদ্ৰিক আৰু অপ্ৰতিসম (asymmetrical) প্ৰাণী। ইহঁত আদিম বহুকোষী প্ৰাণী। লেটিন শব্দ Porus অৰ্থ ছিদ্ৰ আৰু Ferre অৰ্থ বহন কৰা। এই শব্দ দুটিৰ সমন্বয়ত পৰিফেৰা (Porifera) শব্দটো গঠন কৰা হৈছে। ১৮৩৬ চনত বিজ্ঞানী গ্ৰাণ্টে (Grant) প্ৰথম পৰিফেৰা (Porifera) পৰ্বটোৰ নামকৰণ কৰিছিল।^[1]

বৈশিষ্ট্য

বহুকোষী দেহত সুনিৰ্দিষ্ট কলা, কলাতন্ত্ৰ, অঙ্গ আৰু অঙ্গতন্ত্ৰ নাথাকে। প্ৰধানত অসাম্য দেহ, অৰ্থাৎ দেহ কোনো দিশৰ পৰাই সমানভাৱে ভাগ কৰিব পৰা নাযায়। দেহৰ নলিকাতন্ত্ৰ (Canal system) বৰ্তমানেও এই পৰ্বৰ অনন্য বৈশিষ্ট্য। দেহৰ অভ্যন্তৰত কোৱান'চাইট কোষৰ দ্বাৰা আবৃত স্পঞ্জোচিল (Spongocoel) নামৰ গহ্বৰ থাকে যি অছকুলাম (Osculum) নামৰ ডাঙৰ আকাৰৰ ছিদ্ৰেৰে বাহিৰলৈ উন্মুক্ত হৈ থাকে। দেহপ্ৰাচীৰ অষ্টিয়া (Ostia) নামৰ অসংখ্য ক্ষুদ্ৰাকৃতিৰ ছিদ্ৰ বিশিষ্ট, এইবোৰ প'ৰচাইট (porocyte) নামৰ কোষৰ দ্বাৰা গঠিত। দেহত ফ্লেজেলা বিশিষ্ট কোষ পিনাক'চাইট (Pinacocyte) আৰু কোৱান'চাইটৰ (Choanocyte) দ্বাৰা পৰিবেষ্টিত এক বা একাধিক প্ৰকোষ্ঠ (Chamber) থাকে। ইহঁতৰ দেহ ফুলদানি আকৃতিৰ (Vase-like), চুঙা আকৃতিৰ (Cylindrical), নলাকাৰ (Tubular), কুচন আকৃতিৰ (Cushion-shaped) ইত্যাদি আৰু প্ৰতিসাম্যতা (Symmetry) অপ্ৰতিসম (Asymmetry) অথবা পাৰ্শ্বীয় প্ৰতিসম (Radial symmetry)। দেহপ্ৰাচীৰ দ্বিস্তৰ বিশিষ্ট। বাহিৰৰ স্তৰ পিনাক'ডাৰ্ম (Pinacoderm) আৰু ভিতৰৰ স্তৰ কোৱান'ডাৰ্ম (Choanoderm)। উভৰ স্তৰৰ মাজত সাধাৰণতে অকোষীয় (Non-cellular) মেছেনকাইম (Mesenchyme) ধাত্ৰ থাকে য'ত স্পিকিউল (Spicule), স্পঞ্জিন (Spongin) আৰু এমিবয়ড (Amoeboid) কোষ দেখিবলৈ পোৱা যায়। পূৰ্ণাংগ প্ৰাণীবোৰ নিশ্চল (Sessile) অৰ্থাৎ কোনো অবকাঠামোত স্থায়ীভাবে লাগি থাকে। দেহত মুখছিদ্ৰ বা পায়ুছিদ্ৰ নাথাকে। ইহঁত অকলশৰীয়া (Solitary) অথবা উপনিৱেশ (Colonial) গঠন কৰি বাস কৰে। সকলো জলজ প্ৰাণী; বেছিভাগ সামুদ্ৰিক, কিছুমান প্ৰজাতি মৃদুপানীত বাস কৰে। সকলো স্পঞ্জেই উভলিঙ্গী (Hermaphrodite), যদিও ইহঁতে Allogamy তথা cross-fertilization প্ৰদৰ্শন কৰে অৰ্থাৎ একে দেহত স্ত্ৰী আৰু পুৰুষ জননকোষ উৎপন্ন হলেও দুটি ভিন্ন সদস্যৰ স্ত্ৰী আৰু পুৰুষ জননকোষৰ মাধ্যমেও নিষেচন (Fertilization) সম্পন্ন হয়। ইহঁতৰ অযৌন প্ৰজনন মুকুল উৎপাদন বা মুকুলোদগম (Budding), দ্বিবিভাজন বা ফিছন (Fission) আৰু গেমিউল গঠনৰ (Gemmule formation) জৰিয়তে আৰু যৌন প্ৰজনন গেমেট'গনিৰ (Gametogony) যোগেদি হয়। সকলো প্ৰাণীৰ পুনৰুজ্জীৱন ক্ষমতা আছে। দেহেৰ ক্ষতিগ্ৰস্ত অংশৰ পুনঃ উৎপত্তিৰ (Regeneration) ক্ষমতা আছে।

শ্ৰেণীবিন্যাস

১৯৭২ চনত বিজ্ঞানী মেগলিচৰ (Meglitsch) প্ৰদত্ত পৰিফেৰা পৰ্বৰ বৰ্গীকৰণ মূলতঃ অন্তঃকঙ্কালৰ ওপৰত ভিত্তিকৰি নিৰ্মিত।^[2]

শ্ৰেণী: কেলকেৰিয়া (Calcarea)

লেটিন শব্দ Calx যাৰ আভিধানিক অৰ্থ Lime অৰ্থাৎ চুণৰ পৰা কেলকেৰিয়া শব্দটো আহৰণ কৰা হৈছে। সৰু আকৃতিৰ চুণযুক্ত (Calcareous) স্পঞ্জৰ দৈৰ্ঘ্য ১০ ছেমি, ইয়াতকৈও সৰু হয়। দেহাকৃতি চুঙাকৃতিৰ (Cylindrical) বা ফুলদানী (Vase-like) আকৃতিৰ। অকলশৰীয়া (Solitary) বা উপনিৱেশ (Colonial) পাতি বাস কৰে। স্পিকিউল (Spicule) চুণেৰে (Lime) নিৰ্মিত আৰু এক/তিনি/চাৰি ৰশ্মি (Rayed) বিশিষ্ট। ফ্লেজেলাম প্ৰকোষ্ঠ দীঘল আকৃতিৰ। কোৱান'চাইট (Choanocyte) নামৰ কোষবোৰ আকৃতিত ডাঙৰ। সকলো সামুদ্ৰিক। উদাহৰণ: Sycon gelatinosum।

শ্ৰেণী: হেক্সাটিনেলিডা (Hexactinellida)

কাপ (Cup), গোলাকাৰ বা ফুলদানী আকৃতিৰ স্পঞ্জ তুলনামূলকভাৱে বৃহৎ আকাৰৰ, অনেক এক মিটাৰ পৰ্যন্ত হয়। স্পিকিউল (Spicule) ছিলিকাৰ দ্বাৰা নিৰ্মিত (Siliceous) আৰু ছয় ৰশ্মি (Rayed) বিশিষ্ট। ডাৰ্মেল এপিথেলিয়াম (Dermal epithelium) বা এক্সোপিনাকোৰ্ডাম (Exopinacoderm) অনুপস্থিত। ফ্লেজেলাম প্ৰকোষ্ঠ ডিম্বাকৃতিৰ কোৱান'চাইট (Choanocyte) নামৰ কোষবোৰো আকৃতিত সৰু। সকলো সামুদ্ৰিক, অনেক গভীৰ সমুদ্ৰেৰ বাসিন্দা। উদাহৰণ: Euplectella aspergillus।

শ্ৰেণী: ডেম'স্পঞ্জি (Demospongiae)

গ্ৰীক শব্দ Demose যাৰ আভিধানিক অৰ্থ Frame অৰ্থাৎ কাঠামো আৰু Spongos যাৰ আভিধানিক অৰ্থ Sponge অৰ্থাৎ স্পঞ্জৰ পৰা ডেম'স্পঞ্জি শব্দটি আহৰণ কৰা হৈছে। কোৱান'চাইট (Choanocyte) নামৰ কোষবোৰ আকৃতিত সৰু। ফ্লেজেলাম প্ৰকোষ্ঠ গোলাকাৰ বা বৃত্তাকাৰ। অনেক প্ৰাণীৰ স্পিকিউল নাথাকে। যিবোৰৰ থাকে সিহঁতৰ স্পিকিউল ছিলিকা (Siliceous) বা স্পঞ্জিন-তন্তুৰ (Spongin fibre) দ্বাৰা নিৰ্মিত অথবা ছিলিকা আৰু স্পঞ্জিন তন্তুৰ সমন্বয়ত গঠিত আৰু এক বা ছয় ৰশ্মি (Rayed) বিশিষ্ট। সৰুৰ পৰা বৃহৎ আকাৰৰ দেহ ফুলদানী আকৃতিৰ (Vase-like), কাপ আকৃতিৰ (Cup-like), কুছন আকৃতিৰ (Cushion-shaped) আৰু ইহঁত অকলশৰীয়া (Solitary) অথবা উপনিৱেশ (Colonial) গঠন কৰি অৱস্থান কৰে। অধিকাংশই সামুদ্ৰিক, কিছুমান মৃদু পানীৰ বাসিন্দা। উদাহৰণ: Spongilla locustris।

তথ্য সংগ্ৰহ

பஞ்சுயிரிகள் என்றோ பஞ்சுடலிகள் (Sponges) என்றோ அழைக்கப்படும் உயிர்கள் விலங்கினத்தைச் சார்ந்த நீர்வாழ் உயிரினங்களாகும். இவை புழையுடலிகள் (Porifera) என்னும் கணம் அல்லது தொகுதி விலங்கு வகைப்பாட்டுக்குள் அடங்கும். இத்தொகுதி உறுப்பினர்களின் உடலில் பல புழைகள் காணப்படுவதால் இவை புழையுடலிகள் என அழைக்கப்படுகின்றன. இப்புழையுடலிகளே முதலில் தோன்றிய பலக்கல (ஆங்கிலம்:multicellular) உயிர்கள் எனவும் அறியப்படுகிறது.

எல்லாப் பஞ்சுயிரிகளும் நீரில் வாழ்வனவாகும். இவை நீர் நிலைகளில் உள்ள தரைப்பகுதிகளில் ஒட்டி வாழும் உயிர்களாகும். இப்பஞ்சுயிரிகளில் குறைந்தது 5000 வகை சிற்றினங்கள் உலகம் முழுதும் பரவிக்கிடக்கின்றன. இவற்றில் பெரும்பாலானவை கடலில் வாழ்பவை (கடல் பஞ்சுயிரி), ஆயினும் 150 வகை நன்னீர்ப்பஞ்சுயிரிகளும் பதிவுசெய்யப்பட்டுள்ளன.

பஞ்சுடலிகள் மிக எளிய உடற்கட்டமைப்புகளைக் கொண்ட பலக்கல உயிரியாகும். இவற்றின் உடல் சமச்சீரற்ற, வரையறுக்க இயலா அமைப்பைக் கொண்டு காணப்படுகின்றன. கலங்கள் ஒருங்கில்லாமலும், கல வேறுபாடு முற்றிலும் மாறுபட்டும் காணப்படுகின்றன. இதில் உள்ள பெரும்பாலான கலங்கள் இதில் இடம்பெற்றிருக்கும் சாறுகளில் உழன்ற நிலையிலும் காட்சியளிக்கின்றன. இதில் இருந்து பிரிக்கப்பட்ட சிலக் கலங்களைக்கொண்டு ஒரு தனி பஞ்சுடலியே வளர முடியும்.

பண்புகள்

இவை அரித்துண்ணிகளாகும் (Filter feeders). இவை நகராமல் ஒரு நிலையான இடத்தில் தமது ஆதிக்கத்தையும் தமக்கான சூழலையும் உருவாக்கி வாழக்கூடியவை. இவற்றின் உடல் ஈரடுக்குகளால் ஆனது. உடலின் வெளிப்புறத்தில் உள்ள பகுதியை புறப்படை என்றும் உட்புற பகுதியை அகப்படை என்றும் அழைக்கிறோம். புறப்படையையும் அகப்படையையும் இணைக்கும் வழவழப்புள்ள பகுதியை பசைக்கலப்படலம் என விளிக்கிறோம். இவற்றின் உடல்களில் இருபாலினமும் ஒருங்கேக் காணப்படுவதால் இவை ஒரு அழிதூவாகும்.

அகப்படையில் உள்ள கலங்களில் நீண்ட உணர் இழைகளை உடைய கலங்கள், பட்டைக்கலங்கள் (காலர்செல்கள்/கோயனோசைட்ச் - Choanocytes) என அழைக்கப்படுகின்றன. உடலில் பல சிறுசிறுத் துளைகளும் அவ்வுடலின் நடுவில் உள்ள பெருய இடைவெளியாகிய புழையுடலி உட்குழி திறந்து மூடும் தன்மையுடையது. இதை வெளிப்புறத்தே திறக்க ஆசுகுலம் என்னும் பகுதி உதவுகிறது. அகச்சட்டகத்திற்குள் சுண்ணத்தால் (கால்சியம்) ஆன நுண்முட்கள் காணப்படுகின்றன. இவற்றில் கழிவுகள் நீக்கம், சுவாசம் ஆகிய செயல்கள் ஊடுருவல் முறைப்படி நிகழ்கின்றன. சுண்ணாம்புக்களால் ஆன முட்கள் (Spicules) போன்ற அமைப்பே இதன் கல ஒருங்கிணைப்பிற்கும் வடிவத்திற்கும் பெரிதும் துணைநிற்கின்றன.

வாழ்விடம்

இவை நீர்நிலைகளில் உள்ள தரை மற்றும் பாறைகளில் ஒட்டி வாழும் தன்மையுடையன. இவை தமது வாழ்விடத்தை உணவு மற்றும் பாதுகாப்பிற்கு தகுந்தாற்போல் ஏற்ற இடங்களில் காணப்படும் பல வகை திடப்பொருட்களில் ஒட்டி வாழ்கின்றன. இவற்றால் இடப்பெயர்ச்சி செய்ய இயலாது.

மேற்கோள்

• Janet Moore, (2001), An introduction to the invertebrates, 2nd edition, Cambridge University Press, 23-31
• http://www.earthlife.net/inverts/porifera.html
• Porterfield, W. M. (July 1955). "Loofah — The sponge gourd". Economic Botany 9 (3): 211–223. doi:10.1007/BF02859814
• Bergquist, P. R., (1998). "Porifera". In Anderson, D.T.,. Invertebrate Zoology. Oxford University Press. pp. 10–27. ISBN 0195513681.

Sponges, the members of the phylum Porifera (/pəˈrɪfərə/; meaning 'pore bearer'), are a basal animal clade as a sister of the diploblasts.^{[2][3][4][5][6]} They are multicellular organisms that have bodies full of pores and channels allowing water to circulate through them, consisting of jelly-like mesohyl sandwiched between two thin layers of cells.

Sponges have unspecialized cells that can transform into other types and that often migrate between the main cell layers and the mesohyl in the process. Sponges do not have complex nervous,^[7] digestive or circulatory systems like humans. Instead, most rely on maintaining a constant water flow through their bodies to obtain food and oxygen and to remove wastes. Sponges were the first to branch off the evolutionary tree from the last common ancestor of all animals, making them the sister group of all other animals.^[2]

Etymology

The term sponge derives from the Ancient Greek word σπόγγος (spóngos 'sponge').^[8]

Overview

Sponge biodiversity and morphotypes at the lip of a wall site in 60 feet (20 m) of water. Included are the yellow tube sponge, Aplysina fistularis, the purple vase sponge, Niphates digitalis, the red encrusting sponge, Spirastrella coccinea, and the gray rope sponge, Callyspongia sp.

Sponges are similar to other animals in that they are multicellular, heterotrophic, lack cell walls and produce sperm cells. Unlike other animals, they lack true tissues^[9] and organs.^[10] Some of them are radially symmetrical, but most are asymmetrical. The shapes of their bodies are adapted for maximal efficiency of water flow through the central cavity, where the water deposits nutrients and then leaves through a hole called the osculum. Many sponges have internal skeletons of spicules (skeletal-like fragments of calcium carbonate or silicon dioxide), and/or spongin (a modified type of collagen protein).^[9] All adult sponges are sessile aquatic animals, meaning that they attach to an underwater surface and remain fixed in place (i.e., do not travel) while in larval stage of life they are motile. Although there are freshwater species, the great majority are marine (salt-water) species, ranging in habitat from tidal zones to depths exceeding 8,800 m (5.5 mi).

Although most of the approximately 5,000–10,000 known species of sponges feed on bacteria and other microscopic food in the water, some host photosynthesizing microorganisms as endosymbionts, and these alliances often produce more food and oxygen than they consume. A few species of sponges that live in food-poor environments have evolved as carnivores that prey mainly on small crustaceans.^[11]

Sponges reproduce both asexually and sexually. Most species that use sexual reproduction release sperm cells into the water to fertilize ova that in some species are released and in others are retained by the "mother". The fertilized eggs develop into larvae, which swim off in search of places to settle.^[12] Sponges are known for regenerating from fragments that are broken off, although this only works if the fragments include the right types of cells. Some species reproduce by budding. When environmental conditions become less hospitable to the sponges, for example as temperatures drop, many freshwater species and a few marine ones produce gemmules, "survival pods" of unspecialized cells that remain dormant until conditions improve; they then either form completely new sponges or recolonize the skeletons of their parents.^[13]

In most sponges, an internal gelatinous matrix called mesohyl functions as an endoskeleton, and it is the only skeleton in soft sponges that encrust such hard surfaces as rocks. More commonly, the mesohyl is stiffened by mineral spicules, by spongin fibers, or both. Demosponges use spongin; many species have silica spicules, whereas some species have calcium carbonate exoskeletons. Demosponges constitute about 90% of all known sponge species, including all freshwater ones, and they have the widest range of habitats. Calcareous sponges, which have calcium carbonate spicules and, in some species, calcium carbonate exoskeletons, are restricted to relatively shallow marine waters where production of calcium carbonate is easiest.^[14] The fragile glass sponges, with "scaffolding" of silica spicules, are restricted to polar regions and the ocean depths where predators are rare. Fossils of all of these types have been found in rocks dated from 580 million years ago. In addition Archaeocyathids, whose fossils are common in rocks from 530 to 490 million years ago, are now regarded as a type of sponge.

Cells of the protist choanoflagellate clade closely resemble sponge choanocyte cells. Beating of choanocyte flagella draws water through the sponge so that nutrients can be extracted and waste removed.^[15]

The single-celled choanoflagellates resemble the choanocyte cells of sponges which are used to drive their water flow systems and capture most of their food. This along with phylogenetic studies of ribosomal molecules have been used as morphological evidence to suggest sponges are the sister group to the rest of animals.^[16]

The few species of demosponge that have entirely soft fibrous skeletons with no hard elements have been used by humans over thousands of years for several purposes, including as padding and as cleaning tools. By the 1950s, though, these had been overfished so heavily that the industry almost collapsed, and most sponge-like materials are now synthetic. Sponges and their microscopic endosymbionts are now being researched as possible sources of medicines for treating a wide range of diseases. Dolphins have been observed using sponges as tools while foraging.^[17]

Distinguishing features

Sponges constitute the phylum Porifera, and have been defined as sessile metazoans (multicelled immobile animals) that have water intake and outlet openings connected by chambers lined with choanocytes, cells with whip-like flagella.^[18] However, a few carnivorous sponges have lost these water flow systems and the choanocytes.^[19][20] All known living sponges can remold their bodies, as most types of their cells can move within their bodies and a few can change from one type to another.^[20][21]

Even if a few sponges are able to produce mucus – which acts as a microbial barrier in all other animals – no sponge with the ability to secrete a functional mucus layer has been recorded. Without such a mucus layer their living tissue is covered by a layer of microbial symbionts, which can contribute up to 40–50% of the sponge wet mass. This inability to prevent microbes from penetrating their porous tissue could be a major reason why they have never evolved a more complex anatomy.^[22]

Like cnidarians (jellyfish, etc.) and ctenophores (comb jellies), and unlike all other known metazoans, sponges' bodies consist of a non-living jelly-like mass (mesohyl) sandwiched between two main layers of cells.^[23][24] Cnidarians and ctenophores have simple nervous systems, and their cell layers are bound by internal connections and by being mounted on a basement membrane (thin fibrous mat, also known as "basal lamina").^[24] Sponges do not have a nervous system similar to that of vertebrates but may have one that is quite different.^[7] Their middle jelly-like layers have large and varied populations of cells, and some types of cells in their outer layers may move into the middle layer and change their functions.^[21]

Basic structure

Cell types

Mesohyl

Pinacocyte

Choanocyte

Lophocyte

Porocyte

Oocyte

Archeocyte

Sclerocyte

Spicule

Water flow

Main cell types of Porifera^[26]

A sponge's body is hollow and is held in shape by the mesohyl, a jelly-like substance made mainly of collagen and reinforced by a dense network of fibers also made of collagen. The inner surface is covered with choanocytes, cells with cylindrical or conical collars surrounding one flagellum per choanocyte. The wave-like motion of the whip-like flagella drives water through the sponge's body. All sponges have ostia, channels leading to the interior through the mesohyl, and in most sponges these are controlled by tube-like porocytes that form closable inlet valves. Pinacocytes, plate-like cells, form a single-layered external skin over all other parts of the mesohyl that are not covered by choanocytes, and the pinacocytes also digest food particles that are too large to enter the ostia,^[21][23] while those at the base of the animal are responsible for anchoring it.^[23]

Other types of cells live and move within the mesohyl:^[21][23]

• Lophocytes are amoeba-like cells that move slowly through the mesohyl and secrete collagen fibres.
• Collencytes are another type of collagen-producing cell.
• Rhabdiferous cells secrete polysaccharides that also form part of the mesohyl.
• Oocytes and spermatocytes are reproductive cells.
• Sclerocytes secrete the mineralized spicules ("little spines") that form the skeletons of many sponges and in some species provide some defense against predators.
• In addition to or instead of sclerocytes, demosponges have spongocytes that secrete a form of collagen that polymerizes into spongin, a thick fibrous material that stiffens the mesohyl.
• Myocytes ("muscle cells") conduct signals and cause parts of the animal to contract.
• "Grey cells" act as sponges' equivalent of an immune system.
• Archaeocytes (or amoebocytes) are amoeba-like cells that are totipotent, in other words, each is capable of transformation into any other type of cell. They also have important roles in feeding and in clearing debris that block the ostia.

Many larval sponges possess neuron-less eyes that are based on cryptochromes. They mediate phototaxic behavior.^[27]

Glass sponges' syncytia

The glass sponge Euplectella.^[28]

Water flow

Main syncitium

Spicules

Choanosyncitium and collar bodies showing interior

Glass sponges present a distinctive variation on this basic plan. Their spicules, which are made of silica, form a scaffolding-like framework between whose rods the living tissue is suspended like a cobweb that contains most of the cell types.^[21] This tissue is a syncytium that in some ways behaves like many cells that share a single external membrane, and in others like a single cell with multiple nuclei. The mesohyl is absent or minimal. The syncytium's cytoplasm, the soupy fluid that fills the interiors of cells, is organized into "rivers" that transport nuclei, organelles ("organs" within cells) and other substances.^[29] Instead of choanocytes, they have further syncytia, known as choanosyncytia, which form bell-shaped chambers where water enters via perforations. The insides of these chambers are lined with "collar bodies", each consisting of a collar and flagellum but without a nucleus of its own. The motion of the flagella sucks water through passages in the "cobweb" and expels it via the open ends of the bell-shaped chambers.^[21]

Some types of cells have a single nucleus and membrane each but are connected to other single-nucleus cells and to the main syncytium by "bridges" made of cytoplasm. The sclerocytes that build spicules have multiple nuclei, and in glass sponge larvae they are connected to other tissues by cytoplasm bridges; such connections between sclerocytes have not so far been found in adults, but this may simply reflect the difficulty of investigating such small-scale features. The bridges are controlled by "plugged junctions" that apparently permit some substances to pass while blocking others.^[29]

Water flow and body structures

Asconoid

Syconoid

Leuconoid

Pinacocytes

Choanocytes

Mesohyl

Water flow

Porifera body structures^[30]

Most sponges work rather like chimneys: they take in water at the bottom and eject it from the osculum ("little mouth") at the top. Since ambient currents are faster at the top, the suction effect that they produce by Bernoulli's principle does some of the work for free. Sponges can control the water flow by various combinations of wholly or partially closing the osculum and ostia (the intake pores) and varying the beat of the flagella, and may shut it down if there is a lot of sand or silt in the water.^[21]

Although the layers of pinacocytes and choanocytes resemble the epithelia of more complex animals, they are not bound tightly by cell-to-cell connections or a basal lamina (thin fibrous sheet underneath). The flexibility of these layers and re-modeling of the mesohyl by lophocytes allow the animals to adjust their shapes throughout their lives to take maximum advantage of local water currents.^[31]

The simplest body structure in sponges is a tube or vase shape known as "asconoid", but this severely limits the size of the animal. The body structure is characterized by a stalk-like spongocoel surrounded by a single layer of choanocytes. If it is simply scaled up, the ratio of its volume to surface area increases, because surface increases as the square of length or width while volume increases proportionally to the cube. The amount of tissue that needs food and oxygen is determined by the volume, but the pumping capacity that supplies food and oxygen depends on the area covered by choanocytes. Asconoid sponges seldom exceed 1 mm (0.039 in) in diameter.^[21]

Diagram of a syconoid sponge

Some sponges overcome this limitation by adopting the "syconoid" structure, in which the body wall is pleated. The inner pockets of the pleats are lined with choanocytes, which connect to the outer pockets of the pleats by ostia. This increase in the number of choanocytes and hence in pumping capacity enables syconoid sponges to grow up to a few centimeters in diameter.

The "leuconoid" pattern boosts pumping capacity further by filling the interior almost completely with mesohyl that contains a network of chambers lined with choanocytes and connected to each other and to the water intakes and outlet by tubes. Leuconid sponges grow to over 1 m (3.3 ft) in diameter, and the fact that growth in any direction increases the number of choanocyte chambers enables them to take a wider range of forms, for example, "encrusting" sponges whose shapes follow those of the surfaces to which they attach. All freshwater and most shallow-water marine sponges have leuconid bodies. The networks of water passages in glass sponges are similar to the leuconid structure.^[21] In all three types of structure the cross-section area of the choanocyte-lined regions is much greater than that of the intake and outlet channels. This makes the flow slower near the choanocytes and thus makes it easier for them to trap food particles.^[21] For example, in Leuconia, a small leuconoid sponge about 10 centimetres (3.9 in) tall and 1 centimetre (0.39 in) in diameter, water enters each of more than 80,000 intake canals at 6 cm per minute. However, because Leuconia has more than 2 million flagellated chambers whose combined diameter is much greater than that of the canals, water flow through chambers slows to 3.6 cm per hour, making it easy for choanocytes to capture food. All the water is expelled through a single osculum at about 8.5 cm per second, fast enough to carry waste products some distance away.^[32]

Sponge with calcium carbonate skeleton.^[21]

• Pinacocyte
• Choanocyte
• Archeocytes and other cells in mesohyl
• Mesohyl
• Spicules
• Calcium carbonate
• Seabed / rock
• Water flow

Skeleton

In zoology a skeleton is any fairly rigid structure of an animal, irrespective of whether it has joints and irrespective of whether it is biomineralized. The mesohyl functions as an endoskeleton in most sponges, and is the only skeleton in soft sponges that encrust hard surfaces such as rocks. More commonly the mesohyl is stiffened by mineral spicules, by spongin fibers or both. Spicules, which are present in most but not all species,^[33] may be made of silica or calcium carbonate, and vary in shape from simple rods to three-dimensional "stars" with up to six rays. Spicules are produced by sclerocyte cells,^[21] and may be separate, connected by joints, or fused.^[20]

Some sponges also secrete exoskeletons that lie completely outside their organic components. For example, sclerosponges ("hard sponges") have massive calcium carbonate exoskeletons over which the organic matter forms a thin layer with choanocyte chambers in pits in the mineral. These exoskeletons are secreted by the pinacocytes that form the animals' skins.^[21]

Vital functions

Spongia officinalis, "the kitchen sponge", is dark grey when alive.

Movement

Although adult sponges are fundamentally sessile animals, some marine and freshwater species can move across the sea bed at speeds of 1–4 mm (0.039–0.157 in) per day, as a result of amoeba-like movements of pinacocytes and other cells. A few species can contract their whole bodies, and many can close their oscula and ostia. Juveniles drift or swim freely, while adults are stationary.^[21]

Respiration, feeding and excretion

Euplectella aspergillum, a glass sponge known as "Venus' flower basket"

Sponges do not have distinct circulatory, respiratory, digestive, and excretory systems – instead, the water flow system supports all these functions. They filter food particles out of the water flowing through them. Particles larger than 50 micrometers cannot enter the ostia and pinacocytes consume them by phagocytosis (engulfing and intracellular digestion). Particles from 0.5 μm to 50 μm are trapped in the ostia, which taper from the outer to inner ends. These particles are consumed by pinacocytes or by archaeocytes which partially extrude themselves through the walls of the ostia. Bacteria-sized particles, below 0.5 micrometers, pass through the ostia and are caught and consumed by choanocytes.^[21] Since the smallest particles are by far the most common, choanocytes typically capture 80% of a sponge's food supply.^[34] Archaeocytes transport food packaged in vesicles from cells that directly digest food to those that do not. At least one species of sponge has internal fibers that function as tracks for use by nutrient-carrying archaeocytes,^[21] and these tracks also move inert objects.^[23]

It used to be claimed that glass sponges could live on nutrients dissolved in sea water and were very averse to silt.^[35] However, a study in 2007 found no evidence of this and concluded that they extract bacteria and other micro-organisms from water very efficiently (about 79%) and process suspended sediment grains to extract such prey.^[36] Collar bodies digest food and distribute it wrapped in vesicles that are transported by dynein "motor" molecules along bundles of microtubules that run throughout the syncytium.^[21]

Sponges' cells absorb oxygen by diffusion from water into cells as water flows through body, into which carbon dioxide and other soluble waste products such as ammonia also diffuse. Archeocytes remove mineral particles that threaten to block the ostia, transport them through the mesohyl and generally dump them into the outgoing water current, although some species incorporate them into their skeletons.^[21]

Carnivorous sponges

The carnivorous ping-pong tree sponge, Chondrocladia lampadiglobus^[37]

In waters where the supply of food particles is very poor, some species prey on crustaceans and other small animals. So far only 137 species have been discovered.^[38] Most belong to the family Cladorhizidae, but a few members of the Guitarridae and Esperiopsidae are also carnivores.^[39] In most cases, little is known about how they actually capture prey, although some species are thought to use either sticky threads or hooked spicules.^[39][40] Most carnivorous sponges live in deep waters, up to 8,840 m (5.49 mi),^[41] and the development of deep-ocean exploration techniques is expected to lead to the discovery of several more.^[21][39] However, one species has been found in Mediterranean caves at depths of 17–23 m (56–75 ft), alongside the more usual filter-feeding sponges. The cave-dwelling predators capture crustaceans under 1 mm (0.039 in) long by entangling them with fine threads, digest them by enveloping them with further threads over the course of a few days, and then return to their normal shape; there is no evidence that they use venom.^[41]

Most known carnivorous sponges have completely lost the water flow system and choanocytes. However, the genus Chondrocladia uses a highly modified water flow system to inflate balloon-like structures that are used for capturing prey.^[39][42]

Endosymbionts

Freshwater sponges often host green algae as endosymbionts within archaeocytes and other cells and benefit from nutrients produced by the algae. Many marine species host other photosynthesizing organisms, most commonly cyanobacteria but in some cases dinoflagellates. Symbiotic cyanobacteria may form a third of the total mass of living tissue in some sponges, and some sponges gain 48% to 80% of their energy supply from these micro-organisms.^[21] In 2008, a University of Stuttgart team reported that spicules made of silica conduct light into the mesohyl, where the photosynthesizing endosymbionts live.^[43] Sponges that host photosynthesizing organisms are most common in waters with relatively poor supplies of food particles and often have leafy shapes that maximize the amount of sunlight they collect.^[23]

A recently discovered carnivorous sponge that lives near hydrothermal vents hosts methane-eating bacteria and digests some of them.^[23]

"Immune" system

Sponges do not have the complex immune systems of most other animals. However, they reject grafts from other species but accept them from other members of their own species. In a few marine species, gray cells play the leading role in rejection of foreign material. When invaded, they produce a chemical that stops movement of other cells in the affected area, thus preventing the intruder from using the sponge's internal transport systems. If the intrusion persists, the grey cells concentrate in the area and release toxins that kill all cells in the area. The "immune" system can stay in this activated state for up to three weeks.^[23]

Reproduction

Asexual

The freshwater sponge Spongilla lacustris

Sponges have three asexual methods of reproduction: after fragmentation, by budding, and by producing gemmules. Fragments of sponges may be detached by currents or waves. They use the mobility of their pinacocytes and choanocytes and reshaping of the mesohyl to re-attach themselves to a suitable surface and then rebuild themselves as small but functional sponges over the course of several days. The same capabilities enable sponges that have been squeezed through a fine cloth to regenerate.^[44] A sponge fragment can only regenerate if it contains both collencytes to produce mesohyl and archeocytes to produce all the other cell types.^[34] A very few species reproduce by budding.^[45]

Gemmules are "survival pods" which a few marine sponges and many freshwater species produce by the thousands when dying and which some, mainly freshwater species, regularly produce in autumn. Spongocytes make gemmules by wrapping shells of spongin, often reinforced with spicules, round clusters of archeocytes that are full of nutrients.^[46] Freshwater gemmules may also include photosynthesizing symbionts.^[47] The gemmules then become dormant, and in this state can survive cold, drying out, lack of oxygen and extreme variations in salinity.^[21] Freshwater gemmules often do not revive until the temperature drops, stays cold for a few months and then reaches a near-"normal" level.^[47] When a gemmule germinates, the archeocytes round the outside of the cluster transform into pinacocytes, a membrane over a pore in the shell bursts, the cluster of cells slowly emerges, and most of the remaining archeocytes transform into other cell types needed to make a functioning sponge. Gemmules from the same species but different individuals can join forces to form one sponge.^[48] Some gemmules are retained within the parent sponge, and in spring it can be difficult to tell whether an old sponge has revived or been "recolonized" by its own gemmules.^[47]

Sexual

Most sponges are hermaphrodites (function as both sexes simultaneously), although sponges have no gonads (reproductive organs). Sperm are produced by choanocytes or entire choanocyte chambers that sink into the mesohyl and form spermatic cysts while eggs are formed by transformation of archeocytes, or of choanocytes in some species. Each egg generally acquires a yolk by consuming "nurse cells". During spawning, sperm burst out of their cysts and are expelled via the osculum. If they contact another sponge of the same species, the water flow carries them to choanocytes that engulf them but, instead of digesting them, metamorphose to an ameboid form and carry the sperm through the mesohyl to eggs, which in most cases engulf the carrier and its cargo.^[49]

A few species release fertilized eggs into the water, but most retain the eggs until they hatch. There are four types of larvae, but all are balls of cells with an outer layer of cells whose flagellae or cilia enable the larvae to move. After swimming for a few days the larvae sink and crawl until they find a place to settle. Most of the cells transform into archeocytes and then into the types appropriate for their locations in a miniature adult sponge.^[49]

Glass sponge embryos start by dividing into separate cells, but once 32 cells have formed they rapidly transform into larvae that externally are ovoid with a band of cilia round the middle that they use for movement, but internally have the typical glass sponge structure of spicules with a cobweb-like main syncitium draped around and between them and choanosyncytia with multiple collar bodies in the center. The larvae then leave their parents' bodies.^[50]

Life cycle

Sponges in temperate regions live for at most a few years, but some tropical species and perhaps some deep-ocean ones may live for 200 years or more. Some calcified demosponges grow by only 0.2 mm (0.0079 in) per year and, if that rate is constant, specimens 1 m (3.3 ft) wide must be about 5,000 years old. Some sponges start sexual reproduction when only a few weeks old, while others wait until they are several years old.^[21]

Coordination of activities

Adult sponges lack neurons or any other kind of nervous tissue. However, most species have the ability to perform movements that are coordinated all over their bodies, mainly contractions of the pinacocytes, squeezing the water channels and thus expelling excess sediment and other substances that may cause blockages. Some species can contract the osculum independently of the rest of the body. Sponges may also contract in order to reduce the area that is vulnerable to attack by predators. In cases where two sponges are fused, for example if there is a large but still unseparated bud, these contraction waves slowly become coordinated in both of the "Siamese twins". The coordinating mechanism is unknown, but may involve chemicals similar to neurotransmitters.^[51] However, glass sponges rapidly transmit electrical impulses through all parts of the syncytium, and use this to halt the motion of their flagella if the incoming water contains toxins or excessive sediment.^[21] Myocytes are thought to be responsible for closing the osculum and for transmitting signals between different parts of the body.^[23]

Sponges contain genes very similar to those that contain the "recipe" for the post-synaptic density, an important signal-receiving structure in the neurons of all other animals. However, in sponges these genes are only activated in "flask cells" that appear only in larvae and may provide some sensory capability while the larvae are swimming. This raises questions about whether flask cells represent the predecessors of true neurons or are evidence that sponges' ancestors had true neurons but lost them as they adapted to a sessile lifestyle.^[52]

Ecology

Habitats

Euplectella aspergillum is a deep ocean glass sponge; seen here at a depth of 2,572 metres (8,438 ft) off the coast of California

Sponges are worldwide in their distribution, living in a wide range of ocean habitats, from the polar regions to the tropics.^[34] Most live in quiet, clear waters, because sediment stirred up by waves or currents would block their pores, making it difficult for them to feed and breathe.^[35] The greatest numbers of sponges are usually found on firm surfaces such as rocks, but some sponges can attach themselves to soft sediment by means of a root-like base.^[53]

Sponges are more abundant but less diverse in temperate waters than in tropical waters, possibly because organisms that prey on sponges are more abundant in tropical waters.^[54] Glass sponges are the most common in polar waters and in the depths of temperate and tropical seas, as their very porous construction enables them to extract food from these resource-poor waters with the minimum of effort. Demosponges and calcareous sponges are abundant and diverse in shallower non-polar waters.^[55]

The different classes of sponge live in different ranges of habitat:

As primary producers

Sponges with photosynthesizing endosymbionts produce up to three times more oxygen than they consume, as well as more organic matter than they consume. Such contributions to their habitats' resources are significant along Australia's Great Barrier Reef but relatively minor in the Caribbean.^[34]

Defenses

Holes made by clionaid sponge (producing the trace Entobia) after the death of a modern bivalve shell of species Mercenaria mercenaria, from North Carolina

Close-up of the sponge boring Entobia in a modern oyster valve. Note the chambers which are connected by short tunnels.

Many sponges shed spicules, forming a dense carpet several meters deep that keeps away echinoderms which would otherwise prey on the sponges.^[34] They also produce toxins that prevent other sessile organisms such as bryozoans or sea squirts from growing on or near them, making sponges very effective competitors for living space. One of many examples includes ageliferin.

A few species, the Caribbean fire sponge Tedania ignis, cause a severe rash in humans who handle them.^[21] Turtles and some fish feed mainly on sponges. It is often said that sponges produce chemical defenses against such predators.^[21] However, experiments have been unable to establish a relationship between the toxicity of chemicals produced by sponges and how they taste to fish, which would diminish the usefulness of chemical defenses as deterrents. Predation by fish may even help to spread sponges by detaching fragments.^[23] However, some studies have shown fish showing a preference for non chemically defended sponges,^[56] and another study found that high levels of coral predation did predict the presence of chemically defended species.^[57]

Glass sponges produce no toxic chemicals, and live in very deep water where predators are rare.^[35]

Predation

Spongeflies, also known as spongillaflies (Neuroptera, Sisyridae), are specialist predators of freshwater sponges. The female lays her eggs on vegetation overhanging water. The larvae hatch and drop into the water where they seek out sponges to feed on. They use their elongated mouthparts to pierce the sponge and suck the fluids within. The larvae of some species cling to the surface of the sponge while others take refuge in the sponge's internal cavities. The fully grown larvae leave the water and spin a cocoon in which to pupate.^[58]

Bioerosion

The Caribbean chicken-liver sponge Chondrilla nucula secretes toxins that kill coral polyps, allowing the sponges to grow over the coral skeletons.^[21] Others, especially in the family Clionaidae, use corrosive substances secreted by their archeocytes to tunnel into rocks, corals and the shells of dead mollusks.^[21] Sponges may remove up to 1 m (3.3 ft) per year from reefs, creating visible notches just below low-tide level.^[34]

Diseases

Caribbean sponges of the genus Aplysina suffer from Aplysina red band syndrome. This causes Aplysina to develop one or more rust-colored bands, sometimes with adjacent bands of necrotic tissue. These lesions may completely encircle branches of the sponge. The disease appears to be contagious and impacts approximately 10 percent of A. cauliformis on Bahamian reefs.^[59] The rust-colored bands are caused by a cyanobacterium, but it is unknown whether this organism actually causes the disease.^[59][60]

Collaboration with other organisms

In addition to hosting photosynthesizing endosymbionts,^[21] sponges are noted for their wide range of collaborations with other organisms. The relatively large encrusting sponge Lissodendoryx colombiensis is most common on rocky surfaces, but has extended its range into seagrass meadows by letting itself be surrounded or overgrown by seagrass sponges, which are distasteful to the local starfish and therefore protect Lissodendoryx against them; in return, the seagrass sponges get higher positions away from the sea-floor sediment.^[61]

Shrimps of the genus Synalpheus form colonies in sponges, and each shrimp species inhabits a different sponge species, making Synalpheus one of the most diverse crustacean genera. Specifically, Synalpheus regalis utilizes the sponge not only as a food source, but also as a defense against other shrimp and predators.^[62] As many as 16,000 individuals inhabit a single loggerhead sponge, feeding off the larger particles that collect on the sponge as it filters the ocean to feed itself.^[63] Other crustaceans such as hermit crabs commonly have a specific species of sponge, Pseudospongosorites, grow on them as both the sponge and crab occupy gastropod shells until the crab and sponge outgrow the shell, eventually resulting in the crab using the sponge's body as protection instead of the shell until the crab finds a suitable replacement shell.^[64]

Bathymetrical range of some sponge species.^[65] Demosponge Samus anonymus (up to 50 m), hexactinellid Scleroplegma lanterna (~100–600 m), hexactinellid Aulocalyx irregularis (~550–915 m), lithistid demosponge Neoaulaxinia persicum (~500–1700 m)

Generalised food web for sponge reefs^[66]

Sponge loop

Most sponges are detritivores which filter organic debris particles and microscopic life forms from ocean water. In particular, sponges occupy an important role as detritivores in coral reef food webs by recycling detritus to higher trophic levels.^[67]

The hypothesis has been made that coral reef sponges facilitate the transfer of coral-derived organic matter to their associated detritivores via the production of sponge detritus, as shown in the diagram. Several sponge species are able to convert coral-derived DOM into sponge detritus,^[68][69] and transfer organic matter produced by corals further up the reef food web. Corals release organic matter as both dissolved and particulate mucus,^{[70][71][72][73]} as well as cellular material such as expelled Symbiodinium.^[74][75][67]

Organic matter could be transferred from corals to sponges by all these pathways, but DOM likely makes up the largest fraction, as the majority (56 to 80%) of coral mucus dissolves in the water column,^[71] and coral loss of fixed carbon due to expulsion of Symbiodinium is typically negligible (0.01%)^[74] compared with mucus release (up to ~40%).^[76][77] Coral-derived organic matter could also be indirectly transferred to sponges via bacteria, which can also consume coral mucus.^{[78][79][80][67]}

Sponge loop hypothesis. Steps of the sponge loop pathway: (1) corals and algae release exudates as dissolved organic matter (DOM), (2) sponges take up DOM, (3) sponges release detrital particulate organic matter (POM), (4) sponge detritus (POM) is taken up by sponge-associated and free-living detritivores.^[67][81][82]

The sponge holobiont. The sponge holobiont is an example of the concept of nested ecosystems. Key functions carried out by the microbiome (colored arrows) influence holobiont functioning and, through cascading effects, subsequently influence community structure and ecosystem functioning. Environmental factors act at multiple scales to alter microbiome, holobiont, community, and ecosystem scale processes. Thus, factors that alter microbiome functioning can lead to changes at the holobiont, community, or even ecosystem level and vice versa, illustrating the necessity of considering multiple scales when evaluating functioning in nested ecosystems.^[83] (DOM: dissolved organic matter, POM: particulate organic matter, DIN: dissolved inorganic nitrogen)

Sponge holobiont

Besides a one to one symbiotic relationship, it is possible for a host to become symbiotic with a microbial consortium. Sponges are able to host a wide range of microbial communities that can also be very specific. The microbial communities that form a symbiotic relationship with the sponge can amount to as much as 35% of the biomass of its host.^[84] The term for this specific symbiotic relationship, where a microbial consortia pairs with a host is called a holobiotic relationship. The sponge as well as the microbial community associated with it will produce a large range of secondary metabolites that help protect it against predators through mechanisms such as chemical defense.^[85]

Some of these relationships include endosymbionts within bacteriocyte cells, and cyanobacteria or microalgae found below the pinacoderm cell layer where they are able to receive the highest amount of light, used for phototrophy. They can host over 50 different microbial phyla and candidate phyla, including Alphaprotoebacteria, Actinomycetota, Chloroflexota, Nitrospirota, "Cyanobacteria", the taxa Gamma-, the candidate phylum Poribacteria, and Thaumarchaea.^[85]

Systematics and evolutionary history

Taxonomy

Linnaeus, who classified most kinds of sessile animals as belonging to the order Zoophyta in the class Vermes, mistakenly identified the genus Spongia as plants in the order Algae.^[86] For a long time thereafter sponges were assigned to a separate subkingdom, Parazoa ("beside the animals"), separate from the Eumetazoa which formed the rest of the kingdom Animalia.^[87] They have been regarded as a paraphyletic phylum, from which the higher animals have evolved.^[88] Other research indicates Porifera is monophyletic.^[89]

The phylum Porifera is further divided into classes mainly according to the composition of their skeletons:^[20][34]

• Hexactinellida (glass sponges) have silicate spicules, the largest of which have six rays and may be individual or fused.^[20] The main components of their bodies are syncytia in which large numbers of cell share a single external membrane.^[34]
• Calcarea have skeletons made of calcite, a form of calcium carbonate, which may form separate spicules or large masses. All the cells have a single nucleus and membrane.^[34]
• Most Demospongiae have silicate spicules or spongin fibers or both within their soft tissues. However, a few also have massive external skeletons made of aragonite, another form of calcium carbonate.^[20][34] All the cells have a single nucleus and membrane.^[34]
• Archeocyatha are known only as fossils from the Cambrian period.^[87]

In the 1970s, sponges with massive calcium carbonate skeletons were assigned to a separate class, Sclerospongiae, otherwise known as "coralline sponges".^[90] However, in the 1980s it was found that these were all members of either the Calcarea or the Demospongiae.^[91]

So far scientific publications have identified about 9,000 poriferan species,^[34] of which: about 400 are glass sponges; about 500 are calcareous species; and the rest are demosponges.^[21] However, some types of habitat, vertical rock and cave walls and galleries in rock and coral boulders, have been investigated very little, even in shallow seas.^[34]

Classes

Sponges were traditionally distributed in three classes: calcareous sponges (Calcarea), glass sponges (Hexactinellida) and demosponges (Demospongiae). However, studies have shown that the Homoscleromorpha, a group thought to belong to the Demospongiae, is actually phylogenetically well separated.^[92] Therefore, they have recently been recognized as the fourth class of sponges.^[93][94]

Sponges are divided into classes mainly according to the composition of their skeletons:^[23] These are arranged in evolutionary order as shown below in ascending order of their evolution from top to bottom:

Fossil record

Raphidonema faringdonense, a fossil sponge from the Cretaceous of England

1

2

3

4

5

6

7

1: Gap 2: Central cavity 3 Internal wall 4: Pore (all walls have pores) 5 Septum 6 Outer wall 7 Holdfast

Archaeocyathid structure

Although molecular clocks and biomarkers suggest sponges existed well before the Cambrian explosion of life, silica spicules like those of demosponges are absent from the fossil record until the Cambrian.^[96] An unsubstantiated 2002 report exists of spicules in rocks dated around 750 million years ago.^[97] Well-preserved fossil sponges from about 580 million years ago in the Ediacaran period have been found in the Doushantuo Formation. These fossils, which include: spicules; pinacocytes; porocytes; archeocytes; sclerocytes; and the internal cavity, have been classified as demosponges. Fossils of glass sponges have been found from around 540 million years ago in rocks in Australia, China, and Mongolia.^[98] Early Cambrian sponges from Mexico belonging to the genus Kiwetinokia show evidence of fusion of several smaller spicules to form a single large spicule.^[99] Calcium carbonate spicules of calcareous sponges have been found in Early Cambrian rocks from about 530 to 523 million years ago in Australia. Other probable demosponges have been found in the Early Cambrian Chengjiang fauna, from 525 to 520 million years ago.^[100] Fossils found in the Canadian Northwest Territories dating to 890 million years ago may be sponges; if this finding is confirmed, it suggests the first animals appeared before the Neoproterozoic oxygenation event.^[101]

Oxygen content of the atmosphere over the last billion years. If confirmed, the discovery of fossilized sponges dating to 890 million years ago would predate the Neoproterozoic Oxygenation Event.

Freshwater sponges appear to be much younger, as the earliest known fossils date from the Mid-Eocene period about 48 to 40 million years ago.^[98] Although about 90% of modern sponges are demosponges, fossilized remains of this type are less common than those of other types because their skeletons are composed of relatively soft spongin that does not fossilize well.^[102] Earliest sponge symbionts are known from the early Silurian.^[103]

A chemical tracer is 24-isopropylcholestane, which is a stable derivative of 24-isopropylcholesterol, which is said to be produced by demosponges but not by eumetazoans ("true animals", i.e. cnidarians and bilaterians). Since choanoflagellates are thought to be animals' closest single-celled relatives, a team of scientists examined the biochemistry and genes of one choanoflagellate species. They concluded that this species could not produce 24-isopropylcholesterol but that investigation of a wider range of choanoflagellates would be necessary in order to prove that the fossil 24-isopropylcholestane could only have been produced by demosponges.^[104] Although a previous publication reported traces of the chemical 24-isopropylcholestane in ancient rocks dating to 1,800 million years ago,^[105] recent research using a much more accurately dated rock series has revealed that these biomarkers only appear before the end of the Marinoan glaciation approximately 635 million years ago,^[106] and that "Biomarker analysis has yet to reveal any convincing evidence for ancient sponges pre-dating the first globally extensive Neoproterozoic glacial episode (the Sturtian, ~713 million years ago in Oman)". While it has been argued that this 'sponge biomarker' could have originated from marine algae, recent research suggests that the algae's ability to produce this biomarker evolved only in the Carboniferous; as such, the biomarker remains strongly supportive of the presence of demosponges in the Cryogenian.^{[107][108][109]}

Archaeocyathids, which some classify as a type of coralline sponge, are very common fossils in rocks from the Early Cambrian about 530 to 520 million years ago, but apparently died out by the end of the Cambrian 490 million years ago.^[100] It has been suggested that they were produced by: sponges; cnidarians; algae; foraminiferans; a completely separate phylum of animals, Archaeocyatha; or even a completely separate kingdom of life, labeled Archaeata or Inferibionta. Since the 1990s archaeocyathids have been regarded as a distinctive group of sponges.^[87]

= skin

= aragonite

= flesh

Halkieriid sclerite structure^[110]

It is difficult to fit chancelloriids into classifications of sponges or more complex animals. An analysis in 1996 concluded that they were closely related to sponges on the grounds that the detailed structure of chancellorid sclerites ("armor plates") is similar to that of fibers of spongin, a collagen protein, in modern keratose (horny) demosponges such as Darwinella.^[111] However, another analysis in 2002 concluded that chancelloriids are not sponges and may be intermediate between sponges and more complex animals, among other reasons because their skins were thicker and more tightly connected than those of sponges.^[112] In 2008, a detailed analysis of chancelloriids' sclerites concluded that they were very similar to those of halkieriids, mobile bilaterian animals that looked like slugs in chain mail and whose fossils are found in rocks from the very Early Cambrian to the Mid Cambrian. If this is correct, it would create a dilemma, as it is extremely unlikely that totally unrelated organisms could have developed such similar sclerites independently, but the huge difference in the structures of their bodies makes it hard to see how they could be closely related.^[110]

Relationships to other animal groups

A choanoflagellate

Fungi

Choanoflagellates

Glass sponges

Demosponges

Calcareous sponges

Comb jellies

Placozoa

Cnidaria
(jellyfish, etc.)

other metazoans

Plants

Fungi

Most demosponges

Calcareous sponges

Homoscleromorpha

Cnidaria
(jellyfish, etc.)

other metazoans

In the 1990s, sponges were widely regarded as a monophyletic group, all of them having descended from a common ancestor that was itself a sponge, and as the "sister-group" to all other metazoans (multi-celled animals), which themselves form a monophyletic group. On the other hand, some 1990s analyses also revived the idea that animals' nearest evolutionary relatives are choanoflagellates, single-celled organisms very similar to sponges' choanocytes – which would imply that most Metazoa evolved from very sponge-like ancestors and therefore that sponges may not be monophyletic, as the same sponge-like ancestors may have given rise both to modern sponges and to non-sponge members of Metazoa.^[113]

Analyses since 2001 have concluded that Eumetazoa (more complex than sponges) are more closely related to particular groups of sponges than to other sponge groups. Such conclusions imply that sponges are not monophyletic, because the last common ancestor of all sponges would also be a direct ancestor of the Eumetazoa, which are not sponges. A study in 2001 based on comparisons of ribosome DNA concluded that the most fundamental division within sponges was between glass sponges and the rest, and that Eumetazoa are more closely related to calcareous sponges (those with calcium carbonate spicules) than to other types of sponge.^[113] In 2007, one analysis based on comparisons of RNA and another based mainly on comparison of spicules concluded that demosponges and glass sponges are more closely related to each other than either is to the calcareous sponges, which in turn are more closely related to Eumetazoa.^[98][115]

Other anatomical and biochemical evidence links the Eumetazoa with Homoscleromorpha, a sub-group of demosponges. A comparison in 2007 of nuclear DNA, excluding glass sponges and comb jellies, concluded that:

• Homoscleromorpha are most closely related to Eumetazoa;
• calcareous sponges are the next closest;
• the other demosponges are evolutionary "aunts" of these groups; and
• the chancelloriids, bag-like animals whose fossils are found in Cambrian rocks, may be sponges.^[114]

The sperm of Homoscleromorpha share features with the sperm of Eumetazoa, that sperm of other sponges lack. In both Homoscleromorpha and Eumetazoa layers of cells are bound together by attachment to a carpet-like basal membrane composed mainly of "typ IV" collagen, a form of collagen not found in other sponges – although the spongin fibers that reinforce the mesohyl of all demosponges is similar to "type IV" collagen.^[25]

A comb jelly

The analyses described above concluded that sponges are closest to the ancestors of all Metazoa, of all multi-celled animals including both sponges and more complex groups. However, another comparison in 2008 of 150 genes in each of 21 genera, ranging from fungi to humans but including only two species of sponge, suggested that comb jellies (ctenophora) are the most basal lineage of the Metazoa included in the sample.^{[116][117][118][119]} If this is correct, either modern comb jellies developed their complex structures independently of other Metazoa, or sponges' ancestors were more complex and all known sponges are drastically simplified forms. The study recommended further analyses using a wider range of sponges and other simple Metazoa such as Placozoa.^[116]

However, reanalysis of the data showed that the computer algorithms used for analysis were misled by the presence of specific ctenophore genes that were markedly different from those of other species, leaving sponges as either the sister group to all other animals, or an ancestral paraphyletic grade.^[120][121] 'Family trees' constructed using a combination of all available data – morphological, developmental and molecular – concluded that the sponges are in fact a monophyletic group, and with the cnidarians form the sister group to the bilaterians.^[122][123]

A very large and internally consistent alignment of 1,719 proteins at the metazoan scale, published in 2017, showed that (i) sponges – represented by Homoscleromorpha, Calcarea, Hexactinellida, and Demospongiae – are monophyletic, (ii) sponges are sister-group to all other multicellular animals, (iii) ctenophores emerge as the second-earliest branching animal lineage, and (iv) placozoans emerge as the third animal lineage, followed by cnidarians sister-group to bilaterians.^[4]

In March 2021, scientists from Dublin found additional evidence that sponges are the sister group to all other animals.^[124]

Notable spongiologists

Use

Sponges made of sponge gourd for sale alongside sponges of animal origin (Spice Bazaar at Istanbul, Turkey)

By dolphins

A report in 1997 described use of sponges as a tool by bottlenose dolphins in Shark Bay in Western Australia. A dolphin will attach a marine sponge to its rostrum, which is presumably then used to protect it when searching for food in the sandy sea bottom.^[125] The behavior, known as sponging, has only been observed in this bay and is almost exclusively shown by females. A study in 2005 concluded that mothers teach the behavior to their daughters and that all the sponge users are closely related, suggesting that it is a fairly recent innovation.^[17]

By humans

Natural sponges in Tarpon Springs, Florida

Display of natural sponges for sale on Kalymnos in Greece

Skeleton

The calcium carbonate or silica spicules of most sponge genera make them too rough for most uses, but two genera, Hippospongia and Spongia, have soft, entirely fibrous skeletons.^[126] Early Europeans used soft sponges for many purposes, including padding for helmets, portable drinking utensils and municipal water filters. Until the invention of synthetic sponges, they were used as cleaning tools, applicators for paints and ceramic glazes and discreet contraceptives. However, by the mid-20th century, overfishing brought both the animals and the industry close to extinction.^[127]

Many objects with sponge-like textures are now made of substances not derived from poriferans. Synthetic sponges include personal and household cleaning tools, breast implants,^[128] and contraceptive sponges.^[129] Typical materials used are cellulose foam, polyurethane foam, and less frequently, silicone foam.

The luffa "sponge", also spelled loofah, which is commonly sold for use in the kitchen or the shower, is not derived from an animal but mainly from the fibrous "skeleton" of the sponge gourd (Luffa aegyptiaca, Cucurbitaceae).^[130]

Antibiotic compounds

Sponges have medicinal potential due to the presence in sponges themselves or their microbial symbionts of chemicals that may be used to control viruses, bacteria, tumors and fungi.^[131][132]

Other biologically active compounds

Halichondria produces the eribulin precursor halichondrin B

Lacking any protective shell or means of escape, sponges have evolved to synthesize a variety of unusual compounds. One such class is the oxidized fatty acid derivatives called oxylipins. Members of this family have been found to have anti-cancer, anti-bacterial and anti-fungal properties. One example isolated from the Okinawan plakortis sponges, plakoridine A, has shown potential as a cytotoxin to murine lymphoma cells.^[133][134]

See also

• Lists of sponges
• Sponge Reef Project
• SpongeBob SquarePants
• 3-Alkylpyridinium, compounds found in marine Haplosclerida sponges

References