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    Adam Curtis commented on "Pycnopodia helianthoides (Brandt, 1835)":

    Sunflower Star Genus: Pycnopodia
    Species: helianthoides
    ITIS: 157274
    Primary Common Name: Sunflower Star
    Common names (s): Sun star, Sunflower starfish, Many-legged sunflower, Twenty-rayed star
    Synonymous name(s):
    Similar Species: Pycnopodia helianthiodes, Pycnopodia heliathoides, Solaster dawsoni
    General grouping: (pull down on site) --Invertebrates—Sea stars, urchins, cucumbers, sand dollars, brittle stars
    Geographic Range: Northern range limit of the Sunflower star is Alaska, southern range limit is Baja Califor-nia, but they are uncommon south of Carmel Bay.
    Range description: Unalaska (Aleutian Islands) Alaska to Baja California; uncommon south of Carmel Bay. Sunflower Stars are occasionally found in the San Diego/Baja California area, at their southern range limit. Since they prefer areas with dense seaweed vegetation, this is likely a limiting factor of their southern distribution, where seaweeds are less abundant due to warmer water temperatures. These warmer ocean temperatures to the south are also a ma-jor limiting factor of Sunflower Star distribution, as they prefer temperate waters. Sun Stars can be found as far north as Alaska, and the Aleutian Islands, where they are limited by colder waters, and a lack of seaweed habitat further north. Sun Stars can be found on sand, mud, and rocky substrates.
    Brief range description: (this should always be included in above description) Unalaska (Aleutian Islands) Alaska to Baja California; uncommon south of Carmel Bay.
    Habitats (pull down on site)
    Habitat notes: Sunflower stars prefer relatively cold (temperate) waters, in areas with surrounding sea-weeds. Within the MBNMS Sunflower stars can commonly be seen beneath the canopies of Giant Kelp Macrocystis pyrifera, on the sandy or rocky bottom. Pycnopodia helianthoides are abundant from the low intertidal zone, to the subtidal zone (435 m).
    Abundance Relative abundance: Frequent from the low intertidal zone, to the subtidal zone (435 m). They are found on sand, mud, and rock, especially in areas with an abundance of seaweeds. Due to their large geographic range, and their success in ecological competition for space and food, the relative abundance of Sunflower stars is high.
    Species Description: The Sunflower star, Pycnopodia helianthoides , has from 15-24 rays (arms) in adults, while juveniles have as few as 5. Their Latin name (Pycnopodia), means “dense feet,” and (helianthoides) means “sunflower.” Pycnopodia has the largest body diameter of any starfish (40-65 cm). Its large number of arms gives it tremendous predatory advan-tages over other sea stars, in both dexterity and speed. When the Sunflower star becomes excited by food, it can move very rapidly and actively, at a rate of up to 1 meter per minute, greater than any other observed starfish. This species displays a variety of colors including; purple, pink, orange, brown, yellow, and red. Similarly to other sea stars, the Sunflower star has large numbers of tiny tube feet, as well as digestive glands and gonads on its underside, which is a lighter yellowish color. Sunflower stars have eyespots on some of their rays that help them respond to light, currents, and touch. They also have tiny spines, or pinchers along their dermal gills called Pedicellarias, that can be used to catch prey, ward off predators, and hold onto things such as seaweed, which can be used as a form of camouflage.
    Distinctive features: The Sunflower Star has many rays (up to 26 or as few as 15 in adults, and usually 5 in smaller juveniles). They have a broad disk size, flexible and soft, various aboral coloring (purple, pink, red, brown, yellow, and orange). They are the largest and heaviest of all starfish, with a maximum recorded diameter of 90cm (35.4 in.). They are also the most active of all Pacific coast sea stars.
    Key Feature Large body diameter (40-65 cm) soft flexible body, many arms/rays (up to 26), and a va-riety of aboral colors.
    Size: Diameter: 40 to 65 cm (15.7 to 25.6 in.) With record lengths >90cm (35.4 in.) Weight: Average adult ~ (5-11 lbs)
    Natural History General natural history: Pycnopodia helianthoides have Tube feet that use a hydraulic vascular me-chanism that draws in water through the madreporite, enabling grip and locomotion. They also have tiny soft tissue patches of dermal gills that contract when touched. The colora-tion of Sunflower stars is dependent on the proportion of its skin that is exposed, when its gills extend beyond its outer calcareous plate. The sunflower stars skeleton has pieces that are disconnected, unlike most sea stars, which have a semi-rigid one piece skeleton. This allows its mouth to open very wide, and its body to expand to consume its prey. When under attack, Pycnopodia helianthoides can detach their arms (autot-omy), and later regenerate them. An entirely new sea star can form from this detached arm, if a piece of its central disk is still attached.
    Pycnopodia helianthoides has an average life span of 3 to 5 years, and their mating season is typically from March through July. Their main limiting factor is the availability of food, not predation or competition for space. Sunflower stars can react from chemical cues given off by damaged prey. In turn, many invertebrates can sense the approach of predatory sea stars, and have developed an escape response mechanism. The prey of Sunflower stars, use a variety of escape techniques to avoid entrapment and pre-dation. Shelled prey will twist their shells violently, to try and break free from Pycnopo-dia’s powerful tube feet. Others use a pole vaulting technique, or thrashing that allows the prey to swim out of reach. Sea urchins use tiny pinchers, to nibble at the Sunflower stars tube feet, causing them to retract until it eventually retreats.
    Predator(s): The King Crab paralithodes camtschatica captures and feeds upon Sunflower stars and is its main predator, found primarily in Alaska. Other Sea stars (Solaster dawsoni), and rarely sea otters and seagulls will also attack Sunflower stars.
    Prey: The preferred diet of the Sunflower star consists mainly of sea urchins and bivalves. In the MBNMS Sunflower stars feed on dead or dying squid, when they are available seaso-nally. They also feed on a variety of chitons and snails, polychetes, small fish, sea cu-cumbers, hermit and grapsoid crabs, and a variety of other sea stars. The juvenile forms are usually the only target for predators.
    Feeding behavior: (click on site) Feeding behavior notes Sunflower stars are a voracious predator, that will attempt to eat almost anything that they encounter, including their own kind. For this reason they have acquired the nick-name the “Hyena of the sea.” They feed seasonally on squid that die and sink to the bot-tom shortly after the squid’s reproduce. The squid’s pen is indigestible, and the Sunflow-er star is unable to excrete it, so the pens can sometimes be seen extruding through their soft upper body. Sunflower stars may sometimes partially evert their stomachs, in order to gain access its prey. A hunting strategy that is commonly employed by Sunflower stars is to locate clams under the sand, and then dig around the clams, quicker than the clams can escape. This practice leaves large pits in the sand that are a common site for divers. Proximity or contact with Sunflower stars has been found to initiate an escape response in many invertebrate species. The main factors for the Sunflower stars success in competi-tion for space and food are its large size, combined with its ability to use over 15,000 suc-tion tube feet against its competitors and prey.
    Reproduction Pycnopodia helianthoides do not exhibit sexual dimorphism. It uses external broadcast fertilization, and is polygynandrous. Sunflower stars typically breed from March through July, and the peak of their breeding season is in May and June, although fertilizable eggs have been obtained from Sunflower stars from December to June. The separate sexes shed their respective sperm or eggs, where fertilization takes place by ran-dom occurrence. Sunflower stars do not provide parental care; instead their eggs develop into swimming, pelagic, plankton feeding larvae. After no more than 10 weeks, the plankton settles on the sea floor, where it metamorphoses into its juvenile (5 armed) form. Conservation Issues Sewage spills, and urban runoff are harmful to sunflower stars, and the entire marine eco-system. Collection by humans and other anthropogenic disturbances from visitors, pose another threat to the general wellbeing of Sunflower stars. They play a role of secondary importance to the sea otter, in keeping sea urchin populations in check, allowing for higher levels of plant diversity and primary productivity, in turn helping their own larvae gain greater access to food. The population of Sunflower stars as a whole is generally considered healthy and occurs over a fairly broad range. When handled roughly, adult Sunflower stars have been known to shed their arms, and it is common to see them in the field with arms that are being regenerated. It is currently not listed by the IUCN.

    almost 5 years ago • edited: about 3 years ago

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    Adam Curtis commented on "Ophiothrix spiculata Le Conte, 1851":

    Spiny Brittle Star Genus: Ophiothrix Species: Spiculata ITIS: 157794 Primary Common Name: Spiny brittle star Common names (s): Brittle star, serpent star, snake star Synonymous name(s): Ophiothrix dumosa Similar Species: Ophiopteris papillosa General grouping: (pull down on site) --Invertebrates—Sea stars, urchins, cucumbers, sand dollars, brittle stars Geographic Range Range description: Moss Beach (San Mateo CA) to Peru. Often seen under rocks, in rock crevices, and in algal holdfasts, low intertidal zone; subtidal on hard substrata to depths of 2,000 m. Common around and on all reefs where there is any potential hiding place or temporary protection. Brief range description: (this should always be included in above description) Central California to Peru Habitats (pull down on site) Habitat notes: Under rocks, in rock crevices and mats of algae or invertebrates; from low intertidal to 2,000 m deep. Individuals typically insinuate one or more arms into fissures or crevices, anchoring with their straight and hooked arm spines. The remaining arms project into the water, where particles are caught by sticky secretions of spines and podia. The species occupies a wide range of substrates, and in current-swept habitats it can occur in extreme-ly large numbers. Abundance Relative abundance: O. spiculata occurs in large concentrations in favorable habitats. Common around and on all reefs where there is any potential hiding place or temporary protection. Population densities may be very high in certain areas. A siltstone reef in Orange County, bore up to 800 spiculata per 0.1 m². On the rocky bottom and kelp holdfasts at La Holla beach in San Diego, Limbaugh (1955) noted this species occurs in almost un-believable numbers in certain areas. The bottom of deeper water may be covered up to an inch or more by millions of these energetic animals. Specimens are not at all uncommon at the northern extremity of the range. Species Description: The spiny brittle star, Ophiothrix spiculata, has an average disk diameter of (15 mm), and an arm length of about 85 mm. They have long, thorny spines on the mar-gins of the arms and disk, and are found in orange, yellow, tan, brown, and green with various patterns. Brittle stars show beautiful color patterns of metabolically altered caro-tenoid pigments derived from ingested phytoplankton. The variegated patterns seem ela-borately fragmented, enough, perhaps, to confuse visual predators. Prominent thorny spines and longer, pale tube feet protrude from the sides of brittle stars arms. The tube feet are pointed and covered with tiny papillae, and they contain sense organs and mucus-secreting glands. Though lacking in suction cups, they help the animal adhere weakly to the substratum as well as aiding in feeding and respiration. The brittle stars mouth and sieve plate are on the underside. Its saccular gut lacks an anus and, together with the go-nads, fits inside the central disc. Distinctive features: Both disk and arms bearing prominent erect spines adorned with rows of hair-like spine-lets, the ventral arm spines near the arm tips in the form of toothed hooks: each jaw with a cluster of spines (toothed papillae) at the apex, but lacking oral papillae on sides. Brittle stars are so called because their arms readily break off or detach when seized. The animals regenerate these missing parts, while the predator is left with a writhing limb that is mostly skeletal blocks and spines of calcium carbonate. Ophiuroids can coil their arms around objects, holding even after death. Key Feature Distinguised by serrate or conspicuously prickly spines on the disk and arms. Arm spines have jagged edges, radial symmetry with 5 segments. Size: Disc diameter: up to 18 mm, average ~15 mm. Arm length: 5 to 8 times the disk diameter, average ~85 mm. Natural History General natural history: There are approximately 2,000 known species of brittle star, which is more than any other group of sea stars. Brittle stars are strongly related to sea stars. They are characterized by radial symmetry from a central body where five snakelike arms project. The arms are very bendable. Compared to sea stars, brittle stars have a smaller central disc and no anus. Brittle stars are agile, using their entire arms to crawl over the substratum. Most brittle stars are nocturnal, therefore avoiding visual diurnal predators such as fishes. During the day Ophiothrix can be seen with only its arms occasionally extending from the animals hiding places beneath rocks, in the sand, and in kelp holdfasts. Brittle stars are among the most mobile echinoderms. Like sea stars, they do not depend on tube feet, which are sensory tentacles without suction. Brittle stars move moderately quickly, by wriggling their rays which are very bendable and enable the animals to make either rowing or snake-like movements. In ophiuroids the vertebrates are linked by well-structured longitudinal muscles, allowing them to travel horizontally. Ophiuroida moves quickly when distressed. One arm points forward, while the other four act as two pairs of levers, thrusting the body in a series of rapid jerks. Adults do not use their tube feet for locomotion, but very young stages use them as stilts, and they even serve as an adhesive structure. The attribution “brittle” refers to the ability of ophiuroids to voluntarily cast off (auto-tomize) their arms when adversely stimulated. During autotomy, which is under nervous control, the mutable connective tissue linking the arm joints abruptly deteriorates, and the arm immediately disconnects at the weakened junctures. Pieces of the arm that separate from the disk can remain active for many hours. The stump of arm remaining attached to the disk forms a new growing tip and may eventually regenerate to its original length. Spiny brittle stars serve as a major food item for reef fishes, particularly pile perch and they may also compete with smaller fishes and invertebrates for food. Brittle stars gener-ally sexually mature in 2 years, become full grown in 3 to 4 years, and live up to 5 years. Predator(s): The sea star Astrometis sertulifera, elicits an avoidance escape response, and fishes such as the rock wrasse Halichoeres semicinctus, the pile perch Rhacochilus vacca, and the sand bass Paralabrax nebulifer. When roused from a hiding spot their best form of defense is to crawl away. Prey: Drifting particles of plankton and detritus in the water column Feeding behavior: (click on site) Feeding behavior notes: The Spiny brittle star is a scavenger, deposit & suspension feeder. Kelp holdfasts and clumps of bryozoans and worm tubes are often writhing masses of Ophiothrix arms. Individuals anchor themselves with spines from one or more arms, while extending the others into the water column for filter feeding. During feeding, Ophiothrix extends two-thirds of each arm upward, trapping plank-ton and detritus with its tube feet and with mucus strands on its spines. The animal then march food particles along to their mouth with the coordinated skill of their agile tube feet. Papillae that cover the animals tube feet, contain mucus-secreting glands that help adhesion to substrate, as well as aiding in feeding and respiration. Particles are caught by sticky secretions of spines and podia. The podia are papillose, pointed, and remarkably prehensile, wrapping around spines to clean off adherent particles, coiling around small organisms to capture them, and acting in a coordinated fashion with other tube feet on the arm to transfer captured and mucus-entrapped food to the jaws. The jaws close several times on each food mass, compacting the material before it is swallowed. The gut lining lacks cilia, and indeed cilia play no important role in the capture and transfer of food. Reproduction: Few details of reproduction are known. However, spawning has often been noted in July at Pacific Grove CA. The egg sacs of ovigerous specimens may be seen protruding from the disk between the arms. Both eggs and sperm are shed (broadcast spawning), and ferti-lized eggs develop into free swimming, plankton feeding larvae. A few juveniles, pre-sumably arising from settled larvae, have been recovered from fouling panels immersed for 1-month intervals in Monterey Bay from April to August. Possible use of synchronous spawning has been observed in the wild. The animals respire and release waste and gametes through slits at the base of each arm. The gonads, along with its saccular gut and anus, fit inside the central disk. Migration: As they increase in age and body size, many ophiuroids, including California and Oregon intertidal species, migrate from one microhabitat to another. Most large ophiuroids live in bedrock, beneath boulders and cobbles. The smaller species and juve-niles, occur among fronds, holdfasts, and rhizomes of plants, and in protective clumps of bryozoans, hydroids, worm tubes, echinoid spines and so on. Conservation Issues: Used oil from cars, which is poured down the drain, winds up in lakes, rivers, and the ocean. No matter where it comes from, oil harms animals in the ocean. Every year, Americans dispose of 220 million gallons of oil illegally, which is twenty times that of the Exxon Valdez spill. Everything that makes it’s way into the ocean, whether it's littered, washes of the beach, or falls off boats, may ultimately make its way to the ocean. The deep sea is not so far, that it's beyond the reach of human activity. Creatures living in the deep are affected by what humans do on land. Tide-poolers, divers, and Beachcombers, must remember not to disturb or collect any creatures that they come across. Removal of animals from any ecosystem can disrupt the diversity, and ecological processes in areas that are frequently visited.

    almost 5 years ago • edited: about 3 years ago

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    Adam Curtis commented on "Jellyella tuberculata (Bosc 1802)":

    Bryozoan Genus: Membranipora Species: tuberculata ITIS: 155828 Primary Common Name: Kelp encrusting bryozoan Common names (s): Lacy crust bryozoan, Kelp lace bryozoan, Encrusting bryozoan, sea mat Similar Species: Membranipora villosa, Membranipora membranacea General grouping: (pull down on site) Zooplankton Geographic Range Range description: Kelp encrusting bryozoans are prevalent in warm, temperate, and tropical waters of the Atlantic, Pacific, and Indian Oceans, wherever floating Sargassum or Fucus is found. Brief range description: (this should always be included in above description) Atlantic, Pacific, and Indian Oceans Habitats (pull down on site) Habitat notes: Commonly found encrusted on floating brown algae, especially the kelps Macrocystis and Cystaseira, and also on smaller plants in shore, especially the red algae Gelidium, occasionally on shells or wood, low inter-tidal zone to shallow subtidal depths. M. tuberculata is found on gulfweed and rockweed in the Atlantic, and on kelps and other seaweeds in the Pacific. Abundance Relative abundance: M. tuberculata species are among the best-known marine bryozoans, and are commonly found in oceans around the world. Heavy encrusting of kelp fronds with the bryozoan Membranipora is common in kelp forests. Species Description: The kelp encrusting bryozoan, Membranipora tuberculata, is a colony form-ing a white crust, up to several centimeters in diameter. It consists of a single layer of zooids, which have a fine reticulate honeycomb appearance. Individual colonies are 0.5-0.8 mm tall, over 76 mm wide, rectangular, and covered with a lightly calcified mem-brane, with a heavily calcified rim, bearing calcified tubercles at the distal corners, as well as tiny spines projecting from the side of the rim, to the center of an individual. Distinctive features: The membraniporids are the only members of the order Cheilostomata known to have a planktotrophic cyphonautes larva, a free swimming, plankton feeding stage with a triangular bivalve shell. This settles and meta-morphoses into an ancestrula (often double or twinned), which buds to form a flat, en-crusting colony. Key Feature M. tuberculata is known for encrusting the kelp Macrocystis; under favorable conditions colonies grow rapidly and may coalesce to cover entire kelp blades in 3-4 weeks. Overgrown blades often bear 0.5-1 kg of bryozoans per square meter of blade surface, and occasionally perhaps ten times that density. Size: Colony Height: 0.5-0.8 mm Width: more than 76 mm (3 in.) Natural History General natural history: Bryozoans are an ancient group, with a fossil record extending from the early Pleistocene. In the phylum Bryozoa there are about 4,000 species, which makes it one of the major phyla. Over 250 species have been recorded just in California. Forms of the colony vary among different species, which range from flat encrusted sheets, to folded leaf-like bushes. Bryozoans use microscopic mobile pincers called “avicularia” to pluck off any settlers that try to land on them. If pieces of a bryozoan colony break off, the pieces can continue to grow and form new colonies. Colonies increase in size asexually by budding. New colonies are created by hermaphroditic sexual reproduction. The twin shelled larvae of Membranipora, known as cyphonautes, feed in the plankton for several weeks, usually in surface waters, before they settle and metamor-phose. The larvae appear regularly in plankton tows; while drifting freely they fall prey to many pelagic invertebrate predators as well as fishes. Next the cyphonautes settle on a blade of giant kelp and metamorphose into twinned zooid ancestrulas of Membranipora. From this twinned ancestrula, this young colony grows by budding. Within about three weeks, such colonies may spread from this tiny beginning to sheets that completely encase sections of kelp blades and floats; they can add a row of zooids every 18 hours. Infrequently, colonies with spines at the corners of some zooid houses may occur natural-ly; more often the spines are absent. However, in most colonies lacking spines, the spines will develop as a predator induced defense, a response to predation such as from nudi-brancs. Before this induced defense was recognized, spined colonies were thought to be a wholly different species. In laboratory experiments, the predatory defense is triggered in less than one hour, in water that bears chemical cues from predators, which ceases if the predators are removed. The spines greatly impede predation by these predators. Bryozoans are tiny invertebrates, which expand from one, to a colony of thousands, which can encrust an entire kelp blade. Individual bryozoans, called zooids, live within box-shaped compartments made of calcium carbonate, and chitin, material that is found in crab shells. Zooids are extremely small, perhaps smaller than 1/32 of an inch. These tiny larval bryozoans are clam-like swimmers, in bivalve shells. Bryozoans parachute down onto clean kelp blades by opening their shells like umbrellas and drifting down. Always alert for chemical cues, bryozoans test the surface, and then cement themselves to the kelp blades with a sort of sticky glue. Younger bryozoans settle in place and change into adult form, captive within their own shelled rectangular house. After becoming established on the kelp, the lone settlers begin to multiply. Budding off clones in neat rows, a colonies fan out, frosting the blade with a crust of the tiny animals. Predator(s): Bryozoan colonies are important food sources for some nudibrancs, sea urchins and fish Prey: Bacteria, phytoplankton, small organic detritus, and other small organisms. Feeding behavior: (click on site) Feeding behavior notes Bryozoans have a unique feeding appendage, called a lophophore. A lophophore, is a U-shaped, circular ring of tentacles that are ciliated, and used for filter feeding. By extend-ing a crown of tentacles above its shell, bryozoans flick their tentacles through the water to catch small bits of food. Reproduction Feeding and spawning may take place simultaneously. The lophophoral tentacles surround the mouth, which leads to a U-shaped gut. The anus opens just outside the lophophore. There is a lot going on here, but most of it is only revealed under a dissecting microscope. At intervals, small groups of adjacent zooids suddenly retract their lophophores in unison and then suddenly retract them, suggesting a neural connection between zooids. Zooids that are full with ripe eggs, take on an orange color, due to carotenoid pigments from ingested diatoms. Spawned zygotes (fertilized eggs), emerge from the intertenticular organ (the ITO, a short tube lying between two tentacles at the lophophores rim). They bounce from one lophophore to another as they are caught and then rejected in the feed-ing currents of different zooids until they finally reach open water at the edge of the colo-ny. Bryozoan zooids are hermaphroditic. Sperm are released by testes into a zooids body cav-ity, or coelom, and emitted in packets, tail first, through the pore in one of two specia-lized tentacles. As they emerge from the tentacles, many of the sperm packets are swept into exhalent currents and carried away from the colony for possible cross-fertilization in other colonies. Other sperm packets may be drawn into lophophores of sister zooids in the same colony. In either case, the sperm wiggle vigorously amid the lophophores tentacles; a few may be eaten, but many somehow enter the ITO head first and pass into the recipient’s coelom. It isn’t known if a chemo-attractant is involved. Almost 100 percent of the eggs are fertilized as they enter the coelom through the oviduct. The resultant zy-gotes then enter the inner end of the ITO, pass out into the lophophores discharge current, and soon are in the open sea. Embryonic development does not commence until four days after the zygotes are released. Seasonal Behavior Spring and summer Seasonal kelp habitat In spring and summer, habitat for bryozoans is replenished by kelp growth, but later it is reduced and even wholly removed by the loss of canopy from autumn die-back and win-ter storms. This cycle places many constraints on the community. Since kelp blades only live for an average of three months, the sessile animals that colonize them must conform to an exacting timetable of rapid growth, early sex, and a short lifespan. Conservation Issues Bryozoans are studied in great detail, by biochemical scientists. The relatively transparent living colonies are excellent for observations under a microscope. Some bryozoans could have potential medical uses, as they produce a large variety of chemical compounds.

    almost 5 years ago

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    Adam Curtis commented on "Anthopleura midori Uchida and Muramatsu, 1958":

    Giant Green Anemone Genus: Anthopleura Species: xanthogrammica ITIS: 52553 Primary Common Name: Giant green anemone Common names (s): Giant tidepool anemone, solitary anemone Synonymous name(s): Cribrina xanthogrammica Similar Species: Anthopleura elegantissima, Anthopleura Artemisia General grouping: (pull down on site) Corals and anemones Geographic Range Range description: The Giant green anemone inhabits the low to mid intertidal zones of the Pacific Ocean, ranging continuously from Unalaska to Point Conception. It also occurs in areas of cold upwelling, possibly as far south as Panama. Brief range description: (this should always be included in above description) Unlaska to Panama Habitats (pull down on site) Habitat notes: On exposed coastlines, bays and harbors, on seawalls, rocks, tidepools, and pilings; from above low tide line, to about 50 ft. (15 m) depth. Each Giant green anemone is solitary, but is often in tentacle-tip contact with others in favorable tidepools and conditions, and can be found in densities of up to 14 per m². Although their habitat can become crowded, they do not display aggressive behaviors, seen in their smaller relative, A. elegan-tissima. A. xanthogrammica is restricted to the lowest tide zones, where surf and currents continually provide a fresh supply of water, and cannot survive where there is industrial pollution, sewage, or sludgy water. Abundance Relative abundance: A. xanthogrammica is very much at home here in the Monterey Bay, growing to a size exceeded by few other anemones in the world. The giant green anemone is the most frequently observed local marine species by the layman, as it occurs in great numbers within rocky intertidal zones. Species Description: The Giant green anemone, Anthopleura xanthogrammica, is a cylindrical greenish-brown column with green, bluish, or white tentacles; oral disk green, bluish-green, or grayish colors. The scientific name, Anthopleura xanthogrammica means “yellow lined flower.” The column is usually covered with scattered adhesive par-ticles. Numerous thick, short, tapered tentacles in about 6 rings around the flat adhesive oral disk. Very firmly adherent to rocks and pilings; when contracted, the animal forms a hemi-spherical mound. Distinctive features: Stinging cells called cnidocytes are located within the green anemones tentacles. These cells help the anemone paralyze its prey, but can cause no harm to humans. Although it moves slowly through use of its basal disk, it will usually stay attached when the tides move in and out. To prevent from dessication, giant green anemones will retract their ten-tacles and close, during low tides. Key Feature As its name indicates, the Giant green anemone is the largest green anemone in the world. Its column can reach lengths of up to 30 cm, and its crown can reach a diameter of 25 cm. Size: Column diameter: up to 17 cm (6.7 in.) Base: of somewhat greater diameter than the column Height: up to 30 cm (11.8 in.) Tentacular crown diameter: up to 25 cm (9.8 in.) Natural History General natural history: Specimens of A. xanthogrammica that live in direct sunlight are bright green, while specimens found in caves and sun sheltered areas are paler. The quantity of green pigment produced by the anemone, relates to the health and efficiency of the photosyn-thetic symbionts (unicellular green algae and dinoflagellates), which live in the anemones tissue in a mutually beneficial arrangement. The anemones bright green pigment is thought to screen the symbionts from excessively bright light to avoid damage and desiccation. In dim light, the symbionts require as much light as they can get, and the anemones allow this, by producing little or none of the green pigment. In its preference for optimal light levels, the giant green anemone is similar to the aggregating species of Anthopleura. Giant green anemones that are found in deep pools and channels can reach sizes exceeded by few other species. Some Antarctic anemones are larger, specimens which have been reported as over 30 cm in diameter, with stinging capacities comparable to the stinging nettle. Although our form sometimes reaches a diameter of 25 cm, a bare hand can be placed in contact with the tentacles, and feel no more than a slight tingle and disagreeable stickiness. The Giant green anemone has been used in several pharmacological and chemical studies. Its tissues are the source of a new vertebrate heart stimulant and of a pheromone mediating an alarm response in both A. xanthogrammica and A. ele-gantissima. Growth of an individual anemone is often slow, while life spans are quite long. It has been found that A. xanthogrammica can live to an age of more than 80 years. Predator(s): Predators include the nudibranch Aeolidia papillosa, and the snail Epitonium tinctum, both of which feed on the tentacles, and the snails Opalia chacei and O. funiculate, and the sea spider Pycnogonum sternsi, which feed on the column. Sea slugs eat anemones, in-cluding the stinging cells, but they don’t get stung. The slugs use the anemones stingers for defense against predators, by moving them onto their own bodies. A. xantho-grammica can defend itself using stinging cells located in the tentacles. However, these have little affect against larger invertebrates as well as vertebrates. Prey: The diet of A. xanthogrammica consists mainly of mussels, sea urchins, small fish, and crabs that have become detached from the substratum. Feeding behavior: (click on site) Feeding behavior notes The larvae of A. xanthogrammica preferentially settle in mussel beds, in an-ticipation of this future food source. Later, they migrate downward to take up their cha-racteristic position, in the pools and channels below the bed, where they wait for food to drop down from above. Prey are paralyzed and captured after coming into contact with the anemones stinging tentacles. Once the prey has been paralyzed, A. xanthogrammi-ca pulls these animals into its mouth, located in the center of its crown. When digestion is finished, it excretes the waste through the same opening. The epidermis and tissues lining the gut of A. xanthogrammica contain living photosynthetic algae zoochlorellae, and the dinoflagelates zooxanthellae. These symbiotic protists can produce organic nutrients through photosynthesis that may also contribute to the nu-tritional needs of the anemone. Mussels and snails are washed into anemones waiting tentacles, as the wave’s crash against the shore. The anemone eats the animals, then spits out the clean shells. Empty snail shells, may become homes for hermit crabs. The hermit crab Pagarus samu-elis often walks up and down the column of the anemone, even walking through and stroking the tentacles and probing the mouth opening, all without being stung. It is possible that the hermit crab becomes so coated with mucus from the anemone that the anemone responds as if the crab were its own tissue. Hermit crabs which are not pre-viously associated with the anemone may be eaten, or simply taken into the gastrovascular cavity and then later released. Seasonal Behavior Late Spring to Summer Reproduction Giant green anemones release sperm and brownish eggs in late spring and summer, pro-ducing pelagic, planktotrophic larvae. Larval development has not been closely followed, but the larvae swim or float freely for some time, and become widely dispersed. Conservation Issues The giant green anemone will always be found in situations where it is reasonably sheltered from the full force of the surf. For this reason, and because it is quite likely to have been first seen in the tidepool regions, it has been treated as a member of the protected outer coast fauna. A. xanthogrammica cannot survive where there is industrial pollution, sewage, or sludge. Anthopleura xanthogrammica has been the source of several medical studies. Contained within its tissues is a cardiotonic agent that has been associated with favorable stimulatory effects when introduced to the vertebrate heart. Clinical studies show that this agent is a good candidate in the treatment of a failing heart, and has considerable advantages over currently used drugs.

    almost 5 years ago • edited: about 3 years ago

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    Adam Curtis commented on "Pycnopodia helianthoides (Brandt, 1835)":

    Sunflower Star Genus: Pycnopodia Species: helianthoides ITIS: 157274 Primary Common Name: Sunflower Star Common names (s): Sun star, Sunflower starfish, Many-legged sunflower, Twenty-rayed star Synonymous name(s): Similar Species: Pycnopodia helianthiodes, Pycnopodia heliathoides, Solaster dawsoni General grouping: (pull down on site) --Invertebrates—Sea stars, urchins, cucumbers, sand dollars, brittle stars Geographic Range: Northern range limit of the Sunflower star is Alaska, southern range limit is Baja Califor-nia, but they are uncommon south of Carmel Bay. Range description: Unalaska (Aleutian Islands) Alaska to Baja California; uncommon south of Carmel Bay. Sunflower Stars are occasionally found in the San Diego/Baja California area, at their southern range limit. Since they prefer areas with dense seaweed vegetation, this is likely a limiting factor of their southern distribution, where seaweeds are less abundant due to warmer water temperatures. These warmer ocean temperatures to the south are also a ma-jor limiting factor of Sunflower Star distribution, as they prefer temperate waters. Sun Stars can be found as far north as Alaska, and the Aleutian Islands, where they are limited by colder waters, and a lack of seaweed habitat further north. Sun Stars can be found on sand, mud, and rocky substrates. Brief range description: (this should always be included in above description) Unalaska (Aleutian Islands) Alaska to Baja California; uncommon south of Carmel Bay. Habitats (pull down on site) Habitat notes: Sunflower stars prefer relatively cold (temperate) waters, in areas with surrounding sea-weeds. Within the MBNMS Sunflower stars can commonly be seen beneath the canopies of Giant Kelp Macrocystis pyrifera, on the sandy or rocky bottom. Pycnopodia helianthoides are abundant from the low intertidal zone, to the subtidal zone (435 m). Abundance Relative abundance: Frequent from the low intertidal zone, to the subtidal zone (435 m). They are found on sand, mud, and rock, especially in areas with an abundance of seaweeds. Due to their large geographic range, and their success in ecological competition for space and food, the relative abundance of Sunflower stars is high. Species Description: The Sunflower star, Pycnopodia helianthoides , has from 15-24 rays (arms) in adults, while juveniles have as few as 5. Their Latin name (Pycnopodia), means “dense feet,” and (helianthoides) means “sunflower.” Pycnopodia has the largest body diameter of any starfish (40-65 cm). Its large number of arms gives it tremendous predatory advan-tages over other sea stars, in both dexterity and speed. When the Sunflower star becomes excited by food, it can move very rapidly and actively, at a rate of up to 1 meter per minute, greater than any other observed starfish. This species displays a variety of colors including; purple, pink, orange, brown, yellow, and red. Similarly to other sea stars, the Sunflower star has large numbers of tiny tube feet, as well as digestive glands and gonads on its underside, which is a lighter yellowish color. Sunflower stars have eyespots on some of their rays that help them respond to light, currents, and touch. They also have tiny spines, or pinchers along their dermal gills called Pedicellarias, that can be used to catch prey, ward off predators, and hold onto things such as seaweed, which can be used as a form of camouflage. Distinctive features: The Sunflower Star has many rays (up to 26 or as few as 15 in adults, and usually 5 in smaller juveniles). They have a broad disk size, flexible and soft, various aboral coloring (purple, pink, red, brown, yellow, and orange). They are the largest and heaviest of all starfish, with a maximum recorded diameter of 90cm (35.4 in.). They are also the most active of all Pacific coast sea stars. Key Feature Large body diameter (40-65 cm) soft flexible body, many arms/rays (up to 26), and a va-riety of aboral colors. Size: Diameter: 40 to 65 cm (15.7 to 25.6 in.) With record lengths >90cm (35.4 in.) Weight: Average adult ~ (5-11 lbs) Natural History General natural history: Pycnopodia helianthoides have Tube feet that use a hydraulic vascular me-chanism that draws in water through the madreporite, enabling grip and locomotion. They also have tiny soft tissue patches of dermal gills that contract when touched. The colora-tion of Sunflower stars is dependent on the proportion of its skin that is exposed, when its gills extend beyond its outer calcareous plate. The sunflower stars skeleton has pieces that are disconnected, unlike most sea stars, which have a semi-rigid one piece skeleton. This allows its mouth to open very wide, and its body to expand to consume its prey. When under attack, Pycnopodia helianthoides can detach their arms (autot-omy), and later regenerate them. An entirely new sea star can form from this detached arm, if a piece of its central disk is still attached. Pycnopodia helianthoides has an average life span of 3 to 5 years, and their mating season is typically from March through July. Their main limiting factor is the availability of food, not predation or competition for space. Sunflower stars can react from chemical cues given off by damaged prey. In turn, many invertebrates can sense the approach of predatory sea stars, and have developed an escape response mechanism. The prey of Sunflower stars, use a variety of escape techniques to avoid entrapment and pre-dation. Shelled prey will twist their shells violently, to try and break free from Pycnopo-dia’s powerful tube feet. Others use a pole vaulting technique, or thrashing that allows the prey to swim out of reach. Sea urchins use tiny pinchers, to nibble at the Sunflower stars tube feet, causing them to retract until it eventually retreats. Predator(s): The King Crab paralithodes camtschatica captures and feeds upon Sunflower stars and is its main predator, found primarily in Alaska. Other Sea stars (Solaster dawsoni), and rarely sea otters and seagulls will also attack Sunflower stars. Prey: The preferred diet of the Sunflower star consists mainly of sea urchins and bivalves. In the MBNMS Sunflower stars feed on dead or dying squid, when they are available seaso-nally. They also feed on a variety of chitons and snails, polychetes, small fish, sea cu-cumbers, hermit and grapsoid crabs, and a variety of other sea stars. The juvenile forms are usually the only target for predators. Feeding behavior: (click on site) Feeding behavior notes Sunflower stars are a voracious predator, that will attempt to eat almost anything that they encounter, including their own kind. For this reason they have acquired the nick-name the “Hyena of the sea.” They feed seasonally on squid that die and sink to the bot-tom shortly after the squid’s reproduce. The squid’s pen is indigestible, and the Sunflow-er star is unable to excrete it, so the pens can sometimes be seen extruding through their soft upper body. Sunflower stars may sometimes partially evert their stomachs, in order to gain access its prey. A hunting strategy that is commonly employed by Sunflower stars is to locate clams under the sand, and then dig around the clams, quicker than the clams can escape. This practice leaves large pits in the sand that are a common site for divers. Proximity or contact with Sunflower stars has been found to initiate an escape response in many invertebrate species. The main factors for the Sunflower stars success in competi-tion for space and food are its large size, combined with its ability to use over 15,000 suc-tion tube feet against its competitors and prey. Reproduction Pycnopodia helianthoides do not exhibit sexual dimorphism. It uses external broadcast fertilization, and is polygynandrous. Sunflower stars typically breed from March through July, and the peak of their breeding season is in May and June, although fertilizable eggs have been obtained from Sunflower stars from December to June. The separate sexes shed their respective sperm or eggs, where fertilization takes place by ran-dom occurrence. Sunflower stars do not provide parental care; instead their eggs develop into swimming, pelagic, plankton feeding larvae. After no more than 10 weeks, the plankton settles on the sea floor, where it metamorphoses into its juvenile (5 armed) form. Conservation Issues Sewage spills, and urban runoff are harmful to sunflower stars, and the entire marine eco-system. Collection by humans and other anthropogenic disturbances from visitors, pose another threat to the general wellbeing of Sunflower stars. They play a role of secondary importance to the sea otter, in keeping sea urchin populations in check, allowing for higher levels of plant diversity and primary productivity, in turn helping their own larvae gain greater access to food. The population of Sunflower stars as a whole is generally considered healthy and occurs over a fairly broad range. When handled roughly, adult Sunflower stars have been known to shed their arms, and it is common to see them in the field with arms that are being regenerated. It is currently not listed by the IUCN.

    almost 5 years ago • edited: about 3 years ago

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    Adam Curtis commented on "Octopus rubescens Berry, 1953":

    Red Octopus Genus: Octopus Species: Rubescens ITIS: 82606 Primary Common Name: Red octopus Common names (s): Ruby octopus, East Pacific red octopus Similar Species: Octopus dofleini General grouping: (pull down on site) Squid and Octopus Geographic Range Range description: Eastern Pacific Ocean from Mexico to Alaska. Alaska to Scammon's Lagoon, Baja Cali-fornia and in the Gulf of California. O. rubescens is the most common small intertidal octopus in some areas (especially northern California). Brief range description: (this should always be included in above description) Eastern Pacific Ocean from Mexico to Alaska. Habitats (pull down on site) Habitat notes: O. rubescens reside in kelp beds (juveniles often washed ashore in kelp hold-fasts), rocky areas, sandy mud bottoms, under stones on low intertidal; ranges from the intertidal zone to a depth of 1000 feet (300 meters). Abundance Relative abundance: Common offshore in kelp beds or on bottoms of sandy mud to depths of 200 m; occasio-nally under stones in low intertidal zone; juveniles often washed ashore in kelp holdfasts; the commonest small octopus in shallow subtidal waters from Alaska to Baja California. Species Description: The red octopus, Octupus rubescens, has a dorsal mantle length of 5-10 cm (2-4 in.); a round to ovid, dull red or reddish brown often mottled with white. Ocelli ab-sent; skin papillate, often with cirri; arms about 4 times body length, the sixth pairs of suckers enlarged on all but ventral arms of males; ink reddish brown; eggs small (3-4 mm x 1.5-2 mm), the capsules with long stalks twisted into cords, laid in festoons. Elaborate head and camera-like image forming eyes, and a well developed nervous system and re-sulting complex behavior. is highly motile and predatory. Their foot is rolled into the muscular siphon used in jet propulsion. Grasping arms surround the beaked mouth. The shell usually is reduced or absent. Blood moves through an extensive closed circulatory system. Members of the Order Octopoda are mostly noc-turnal and fond of hiding in dens, which range from rocky crevices to gastropod shells to kelp holdfasts, and can often be identified by the nearby carapaces of the octopus’ prey. Distinctive features: O. rubescens has the largest and most complex brain, as well as the best eyes, of any invertebrate. The Octopus can also move rapidly over sand or rocks by the use of its arms and suckers; but in open water its arms trail away from the direction of motion with an efficient streamlined effect, as it propels itself backwards with powerful jets of water from its siphon tube. The octopuses themselves are difficult to find, because of their reclusive tendencies, they are masters of camouflage, quick to match any back-ground. Their swift color and pattern changes are made possible by a network of pigment sacs (cromatophores), reflective platelets (iridophores), and refractive platelets (leuco-phores) in the skin, as well as superficial muscles that permit texture control. Key Feature The octopus has an ink sack, opening near the anus, from which it can discharge a dense, sepia-colored fluid, creating a smoke screen, and it can also change its color patterns to become concealed in its surroundings. Size: Length: up to 50 cm (20 in.) Weight: about 1 lb. (16 oz.) Natural History General natural history: Octopus eyes are very similar to vertebrate eyes, with retinas, pupils and lenses. Although they have very good eyesight, they use smell and touch to find food; with thousands of chemical receptors, and millions of texture receptors, which line the rims of their suckers. Octopi scour the sandy seafloor, flushing out small prey, or crawl in and out of rocky areas, hunting crab and shrimp. Red octopi live for roughly two years. They start life as larvae in the shallow subtidal and intertidal zones, spending a short time as drifting plankton. They later change into adult form, before settling as juveniles on kelp holdfasts. Finally, they migrate farther offshore, where they settle on sandy mud sea bottoms. According to researchers who explore Monterey Canyons with an ROV’s (remotely op-erated vehicles), red octopi are the most common animals found along the continental shelf, around depths of 600 feet (183 m). Red octopi mate in late winter and early spring, before moving into the intertidal area where spawning takes place. Females protect and groom their eggs until the larvae hatches six to eight weeks later. Then the females die; while the males die soon after mating. Octopi are highly developed marine mollusks. They have three hearts; one that pumps blood through the body, and two more to pump blood through its gills. Researchers consider octopi to be the most intelligent invertebrates, possibly as intelligent as house cats. A red octopus’s normal color is actually reddish brown, but like other octopuses it can change, in a fraction of a second, to brown, yellow, red, white, or a variety of mottled colors. In order to defend themselves and for social signaling (such as courting), octopus-es change their color patterns to that which contrasts with their surroundings. Camouflag-ing themselves, octopuses can change to color patterns, which blend to their surroundings. They can also alter their skin texture, to match the surface of smooth or rough rocks, or sand. An octopus typically forages at night, collecting multiple specimens before re-treating to its den, where it dines in comfort. An octopus deposits shells that are empty, outside its den in a pile, called an “octopus’s garden.” Predator(s): Various bass (Paralabrax spp.), rockfishes (Sebastodes spp.), California sea lions, and the common seal. Prey: Mollusks, fishes, and Crustaceans, they especially seem to prefer small crabs and hermit crabs. Feeding behavior: (click on site) Feeding behavior notes One common method this animal uses for hunting is to lie quietly under rocks and then dart out to capture passing fish or crustaceans. Captured prey are quickly subdued by po-tent, paralyzing venom and then opened at the junction between carapace and abdomen with the strong, beaklike jaws, which are normally hidden inside the mouth opening. Aquarium specimens have been known to drill and eat a variety of gastropods. In the field, small crabs and hermit crabs seem to be preferred. After the viscera are eaten, the legs are pulled off and cleaned out one by one. If the prey is a snail, the octopus drills a hole in the snail’s shell with its radula and injects a chemical that dissolves the snail’s flesh from its shell. Seasonal Behavior August-September Reproduction The octopus’s method of reproduction is decidedly unique. At breeding time one arm of the male enlarges and is modified as a copulatory organ. From the generative orifice he charges this arm with a packet of spermatozoa, which he deposits under the mantle skirt of the female. A part of the arm is detached, and carried around in the mantle cavity of the female until fertilization takes place, often several days. The detached arm was for-merly thought to be a separate animal that was parasitic in the female cephalopod. Fe-males guard egg clusters intertidally or shallow subtidally from late spring through early winter in rocky areas. Breeding peaks, are in August and September. Young octopi hatch within 6-8 weeks, spending a brief time in the plankton, and later settle as juveniles with-in the kelp beds. Large individuals migrate farther offshore to sandy mud bottoms. Dur-ing late spring, they mate in deep water, and then later move inshore. Conservation Issues O. rubescens are often found among prawn traps. When tidepooling, you could see a red octopus in the intertidal zone, but it’s best to not touch it. Red octopuses-beaks are sharp, and they are inclined to bite, and then spit venom into the wound. Heal-ing from an octopus bite can take up to three weeks.

    almost 5 years ago • edited: about 3 years ago

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    Adam Curtis commented on "Strongylocentrotus purpuratus (Stimpson, 1857)":

    Purple Sea Urchin Genus: Strongylocentrotus Species: purpuratus ITIS: 157975 Primary Common Name: Purple sea urchin Common names (s): California purple urchin, purple urchin Similar Species: Strongylocentrotus franciscanus General grouping: (pull down on site) Sea stars, urchins, cucumbers, sand dollars, brittle stars Geographic Range Range description: Purple sea urchins are found on the pacific coastline from Alaska to Cedros Island, Mex-ico. Above the low tide line, these urchins often live in rounded depressions in the rock which slowly erode with their teeth and spines. Common in lower intertidal zone on rocky shores and pilings, typically in areas of moderate to strong wave action. Brief range description: (this should always be included in above description) Alaska to Cedros Island, Mexico. Habitats (pull down on site) Habitat notes: Purple sea urchins are primarily found in the low intertidal zone. Purple sea urchins thrive in areas with strong wave action and churning aerated water. Giant kelp forests provide a feast for S. purpuratus. Purple sea urchins can be found on the sea floor near the holdfast of the kelp. Low intertidal to 160m (525 ft.) depth. Abundance Relative abundance: Purple urchins show strong regional-scale patterns of abundance that were correlated to the distribution of their primary predator, the southern sea otter. Since the return of the voracious sea otter to the Monterey Bay sea urchins have become crevice dwellers that avoid exposed sites, obtaining sustenance not from living seaweeds but from detached kelp blades that drift within their grasp. Nevertheless, the urchins in the area are vulnerable, and evidence of purple sea urchins is found in sea otter scat, and the otters bones become stained purple. Species Description: The purple sea urchin has a rounded body that consists of a radially symmetrical test, covered with large spines. The test itself varies from 50mm in diameter up to 100mm in diameter. The test is covered with spines, which are usually bright purple in adults. Urc-hins that are younger, have purple tinged spines that are primarily pale green in color. Also covering the test, are pedicellariae and tube feet. The oral side of an urchin is normally the side facing the substrate, and the aboral side of an urchin is normally the side of the urchin facing the observer. Female and male urchins are monomorphic; not physically different from one another. Distinctive features: Purple sea urchins often decorate themselves in a manner similar to decorator crabs. This is done to protect from UV light, dessication, and visual predators. The skeleton, called a test, consists of rows of radially arranged plates permanently joined to each other. Move-able purple spines, each with a concave base, fit on correspondingly convex bumps on each plate. Muscle fibers attached to each spine enable it to move in any direction. In sea urchins, the middle of the upper surface has a circular area, usually with scaly plates, bearing the anus. It is surrounded by 5 petal-shaped plates, each with a large pore, the opening of a sex duct. One of these plates is also full of small pores, and is the sieve plate. Tube feet on an urchin are arranged in 5 pairs of rows that extend longitudinally around the test. They are tipped with suckers, and are long enough to reach beyond the spines. The tube feet are used in respiratory exchange, locomotion, and decorating. Urc-hins also have stalked pinchers, all of which have 3 jaws, and some have poison glands. These structures are defensive, protecting against predators and discouraging larval ani-mals from settling on the urchins. Key Feature Strong radial symmetry, vivid purple, spiny, oval, domed aboral and flattened oral sur-faces. Size: Width: 50 to 100 mm (2 to 4 in.) Height: average ~ 44 mm (1 ¾ in.) Natural History General natural history: Purple sea urchins have adapted the ability to burrow itself into substrate. In most cases that substrate is rock. Strongylocentrotus purpuratus uses five bony teeth in combination with its spines, to slowly scrape away at the substrate. This results in a de-pression in the substrate into which the urchin can settle with a firm grip. The hard surface of the rock or substrate that S. purpuratus scrapes, does wear out its spines. However, this does not create a problem since the spines are being continually renewed by growth. This feature is unique, and can sometimes prove deadly. When purple sea urchins are young, they may start to scrape into the substrate. As they grow, urchins may find themselves trapped for life. As the urchin grows, it gouges out a big enough cavity for its body to fit. Since the initial entrance hole was made when the urchin was much smaller, once grown it may be unable to escape from its self-created depression. S. purpatus requires well-oxygenated water, obtaining oxygen mainly through their tube feet, which are extended at least partway when under water. Symbionts of purple sea urchins include ciliated protozoans and the flatworm Syndisyrinx franciscanus in the gut, and externally the purple polychaete Flabelligera commensalis and the isopod Colidotea rostrata which live among its spines. Although the purple sea urchin has been important for biomedical research, its ageing process has not been studied in much detail. The species grows rather slowly, with large size reached after about 10 years. Based on those growth rates, it has been estimated that these animals may live for more than 50 years. Since evidence suggests that the red sea urchin is extremely long-lived with no detectable signs of ageing, the purple sea urchin may also be extremely long-lived and its maximum longevity may be considerably underestimated. Predator(s): Primary predators of S. purpuratus include sea stars (Solaster stimpso-ni, Pycnopodia helianthoides, and Astrometis sertulifera) as well as the sea otter. The purple sea urchin defends itself with its rather sharp spines. Prey: As sedentary invertebrates, S. purpuratus primarily feed on algae. Pieces of algae are a common food that urchins grab out of the water. S. purpura-tus can also scrape algae off the substrate or rocks. While any algae satisfies the appetite of the purple sea urchin, the species prefers giant kelp Macrocystis pyrife-ra. Feeding behavior: (click on site) Feeding behavior notes The spines, pedicellariae, and tube feet that cover S. purpuratusare used to grab the food and aid it into the mouth. Its mouth is composed of a strong jaw piece called Aristotle's lantern. This remarkable structure consists of a set of skeletal rods and muscles arranged to open and close 5 teeth, like the jaws of a drill chuck. The lantern can be protruded out of and completely retracted back into the mouth. The five bony teeth are instrumental in scraping algae off the substrate. The area around the mouth is usually adorned with 10 frilly gills. Purple sea urchins feed on giant kelp. During feeding, urchins can destroy entire kelp forests. These kelp forests are commercially important for fisheries, and the blades of kelp can be harvested for algin. General Behavior S. purpuratus is both an independent and a social organism. Urchins are found in groups, especially when a good food source is near. Strongylocentrotus purpuratus can be found in very high numbers around the holdfasts of giant kelp beds. This juxtaposed to low tide, when purple sea urchins can be found all by individual-ly. Strongylocentrotus purpuratus is a largely sedentary individual. However, purple urchins do have the ability to move, and do so by using their tube feet to push and pull themselves along. Movement is often extremely slow. S. purpuratus pedicellariae can grab and pinch a predator to ward them off. Pedicellariae also keep sponges, barnacles, and other animals from growing on the aboral (top) surface of the urchin. Seasonal Behavior January-March Reproduction Sexes are separate, although some hermaphrodites may be found. January, February, and March are the primary reproductive months for S. purpuratus. However it has been noted that ripe individuals can be found even through the month of July. Sea urchins breed once a year. Purple sea urchins reach sexual maturity at the age of about two years, at that time they are about 25mm or greater in diameter. Once they have reached sexual maturity, females and males release gametes into the ocean, where fertili-zation takes place. The fertilized egg later settles, and begins growing into an adult. Upon fertilization and settling onto a substrate, the urchin starts to develop. The shell or test develops quickly to protect the developing urchin. Plates of the test begin to form indivi-dually and then grow tighter together to form the test. Conservation Issues Strongylocentrotus purpuratus is used for many seafood recipes. Sea urchin is commonly used to make sushi. It is also considered a delicacy in many countries, including Japan. The main urchin harvesting company in California sends 75% of their harvest to Japan. The market value for sea urchins in Japan ranges from $2.20 to $43.00 per tray. In 1994, Japan imported over 6, 130 metric tons of sea urchins, totaling a value of 251 million dollars. Sea urchin harvesting is one of the highest valued fisheries in California, bringing about 80 million dollars in export value per year. Strongylocentrotus purpuratus, currently has no special status listing. However, harvesting of sea urchins poses concerns for the welfare of the overall sea urchin population. Sea urchins are being exported to other countries such as Japan, in extremely high numbers, leading some to believe that the populations of sea urchins are dramatically declining. The California Department of Fish and Game is now trying to control harvesting of sea urchins, to insure urchin populations don’t become endangered. There is now simply a limit to the number of permits available for fisheries. There are discussions over other conservation techniques as well, which have not been implemented yet.

    almost 5 years ago

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    Adam Curtis commented on "Loxorhynchus crispatus Stimpson, 1857":

    Decorator Crab Genus: Loxorhynchus Species: crispatus ITIS: 98478 Primary Common Name: Decorator crab Common names (s): Moss crab, masking crab Similar Species: Scyra acutifrons General grouping: (pull down on site) Crabs, barnacles, shrimp, lobster Geographic Range Range description: Northern California, Redding rock (Humboldt County) to Isla Natividad (Baja, Southern California). Brief range description: (this should always be included in above description) Redding rock (Humboldt Co.) to Isla Natividad (Baja California) Habitats (pull down on site) Habitat notes: The decorator crab can be found locally on rocks, pilings, and kelp holdfasts; below low-tide line to water 600 ft. (183 m) deep. Occurs in sublitoral; low intertidal areas on semi protected rocky coasts in crevices; often heavily decorated with hydroids, sponges, and algae. Large individuals are often are found clinging, head down, on vertical walls and pilings. Abundance Relative abundance: Scarce in low intertidal zone on rocky shores of protected outer coast, much more com-mon on subtidal pilings, kelp holdfasts, and rocks to 183 m depth. Species Description: The Decorator crab, Loxorhynchus crispatus, is pear shaped, and covered with growth. It is a grayish-brown color, covered with short, brownish hairs, and has white fingertips. Carapace is widest in the rear third; side margin without spines; beak notched at the tip, thick, moderately long, bent down slightly; sharp spine above and one beside eye. Pincers long, slender; fingers short; 2nd pair of walking legs longest, 5th is the shortest. L. crispatus is generally a slow-moving crab, at least during the day and when left alone. But at night it is more active, and if harassed it is quite capable of scuttling across the bottom at a respectable pace, or scampering off of a ledge and para-chuting down with outstretched legs. Until it moves, however, one may never suspect that the crab is even there. Distinctive features: To some animals the accidental growth of algae or sessile animals on their shells seems to be a source of danger, presumably because the weight and the water resistance of such growth might inhibit their movement or ability to cling to the substratum. Others tolerate such growths, and still others, such as L. crispatus, go to the extreme of augmenting the natural growths by planting hydroids, algae, sponges, etc. on their backs. Although mask-ing may serve the dual purpose of concealment from predators, and prey, L. crispatus uses masking primarily for defense, as its diet consist largely of sessile animals. Key Feature Decorator crabs attach masking materials to their bodies by wedging or impaling them among hooked setae on the back and legs. Size: Carapace width males: up to 8.8 cm (3.5 in.) Carapace width females: up to 6.8 cm (2.7 in.) Carapace length: up to 10 cm (3.9 in.) Natural History General natural history: L. crispatus uses hooked setae on their back and legs, to attach masking ma-terials to their bodies. Crabs that have had these hooks removed experimentally cannot attach materials until their next molt, when a new set of hooks are produced. Masking materials are normally removed from the cast-off exuvia of the molt and recycled in re-decorating the crab’s new exterior. Large crabs, especially males over 8 cm in carapace width, apparently no longer actively decorate their backs, but may nevertheless be cov-ered by various growths that have settled and grown there without assistance. Other sen-sory bristles inform the crab about the status and position of its decorations. These mate-rials remain alive on the crab and are held in position by special hooked setae. Many of these interactions are symbiotic, in which anemones and sponges benefit from constant water currents via the crabs walking motion, and are able to take advantage of leftovers of the crab’s meal. Excess decoration may increase energy costs such as mobility, feeding, and escape strategies. However, it has been shown that algae on their carapace can serve as an alternate food source. Relative growth techniques are very useful in maturation studies. The relative size of claws is also an aid to recognition of social systems. Males with particularly large claws are generally dominant, and males of different sizes and claw development may adopt very different behavioral reproduction strategies. Discontinuity of growth is one of the most singular aspects of the lives of arthropods. Ecdysis, is the process of shedding the old skin, called the exuvia, and the accompanying increase in size only takes a few mi-nutes. However, the entire interval between molts represents a dynamic, cyclical process. Following ecdysis the animal is soft, until the cuticle gradually hardens as different areas of the exoskeleton calcify sequentially. Before its new shell hardens, the crab absorbs wa-ter and expands to a size larger than before the molt. While the new shell is solidifying, the crab hides from predators. Post molt ends with the deposition of a thin, membranous layer. The premolt period, is signaled by the separation of the epidermis from the cuticle. A mi-totic burst, expanding the number of epidermis cells, precedes the deposition of new cuti-cular structures. First, new setae are organized using the previous cuticle as a template. After the new setae are organized, pre-exuvial layers are secreted over the general body surface. Molting is imminent if the epimeral suture of a crab is visibly split. Exuviae can be distinguished from empty remains of a dead animal, by the absence of pigment from the corneas of the eyestalks of the exuvia. Discovery of an intact fragile exuvia suggests that a very soft, recently molted animal may be nearby hiding. The pre-vious owner of the exuvia can by identified by matching the details of pigment patterns of the exuvia, with the soft animal. Comparison of the soft animal and its exuvia demon-strates the growth increment per molt for animals of that particular size. Decapods are able to cast off (autotomize) their limbs under stress, and then later regene-rate the appendages at subsequent molts. Autotomy is easily demonstrated by squeezing the basal segments of an appendage. A specific muscle is stimulated, which slices through a cuticular apodeme, severing the limb. The autotomized limb is severed at a preformed breakage plane. Upon autotomy, a flap of skin seals over the severed limb base so that barely a drop of blood is lost. The regenerating limb forms in a bud, which protrudes from the stump of the autotomized limb. Recently regenerated appendages are somewhat smaller than normal limbs, but this size discrepancy is no longer apparent after several molting cycles. Predator(s): O. rubescens, fish, and some marine mammals. Prey: L. crispatus is a generalist omnivore that feeds on drift kelp, and a variety of both living and dead sessile invertebrates, such as worms and mollusks. Feeding behavior: (click on site) Feeding behavior notes Crabs are omnivores, feeding primarily on algae, and taking any other food, includ-ing molluscs, worms, other crustaceans, fungi, bacteria and detritus, depending on their availability and the crab species. For most crabs, a mixed diet of both animal and plant matter results in the greatest fitness and fastest growth. Algae on the animal’s carapace can also serve as an alternate food source. Reproduction L. crispatus reproduces sexually. Upon reaching sexual maturity, most if not all decapods undergo a molt of puberty to attain their adult morphology. Ovaries of deca-pod Crustacea lie dorsally to other organs in the carapace and the anterior part of the ab-domen. Eggs that are recently laid rest in a gelatinous mass on the crabs pleopods (swimming legs). Within one day, an outer membrane forms around each egg and a thin strand attaches it to the pleopodal setae. Young eggs are generally evenly pigmented. As the yolk is gradually displaced by the growing embryo, a transparent area appears in the egg; in advanced embryos, eyespots and larval chromatophores may also be recognized. Broods that are about to hatch, often have a grayish cast since all the brightly colored yolk has been absorbed. Information about the reproductive state of male decapods is rel-atively difficult to obtain, dissection and microscopic examination are often required. Most crustaceans deposit a single brood in an instar (stage). Conservation Issues Decorator crabs are a main food source for some fishes, including croakers and cabezon. Presently the population of decorator crabs is not in danger; however, pesticides, oil runoff, chemicals, and paint solvents threaten the crabs’ habitats. As stewards of the oceans, we must carefully dispose of hazardous materials like these or, better yet, use environmentally safe products.

    almost 5 years ago

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    Adam Curtis commented on "Apostichopus parvimensis (Clark, 1913)":

    Warty Sea Cucumber Genus: Parastichopus Species: Parvimensis ITIS: 158343 Primary Common Name: Warty sea cucumber Common name: Sea cucumber Synonymous name(s): Stichopus parvimensis Similar Species: Parastichopus californicus General grouping: (pull down on site) Sea stars, urchins, cucumbers, sand dollars, brittle stars Geographic Range Range description: Monterey Bay to Punta San Bartolome (Baja California); uncommon and found only sub-tidally north of point Conception. Brief range description: (this should always be included in above description) Monterey Bay to Baja California. Habitats (pull down on site) Habitat notes: P. parvimensis is common on sandy or sandy-mud surfaces and between rocks, low intertidal zone of bays and well protected rocky shores; from the subtidal zone to at least 29 m, on rocks, pilings, sandy or mud bottoms, and, in tropical regions, in sea-grass beds. Abundance Relative abundance: Common on rocks at kelp forest depths in the Monterey region. Species Description: The Warty sea cucumber, Parastichopus parvimensis, has a cylindrical, highly contractile body, that can be black, brown, or red in color. The animals are covered above with elongate warts, and below with tube feet for locomotion and attachment to substrate. This imposes an almost bilaterally symmetrical pattern on these radially symmetrical animals. P. parvimensis is an epibenthic deposit-feeding holo-thurian. Members of the class holothuroiea are generally called sea cucumbers, though some of them bear no particular resemblance to the vegetable. Cucumbers may be flaccid when undisturbed, but when annoyed they become stiff and turgid, shorter in length, and thick. The body wall consists of a layer of circular muscles, connective tissue, and skin. The contraction of these circular and longitudinal muscle layers produces a wormlike or peristaltic action. Distinctive features: This species creeps more rapidly than most cucumbers (about 1 m in 15 min.). Holothu-roids differ from echinoderms, because they have a water vascular system full of body fluid rather than sea water. When annoyed, P. parvimensis spews out its in-ternal anatomy in a kind of autotomy, a trait that has protective values. Within two to four weeks the viscera will regenerate. In the usual evisceration, the hindgut just inside the anus is ruptured by the pressure of water caused by a sudden contraction of body-wall muscles. This contraction voids first the respiratory trees and subsequently the remainder of the internal organs. The water-vascular system characteristic of echinoderms is manifest in the cucumbers tube feet used for locomotion and feeding. The tentacles around the mouth are actually modified tube feet. Like other echinoderms, cucumbers have a calcareous skeleton; but in their case it is only vestigial, composed of plates and spicules of lime buried in the skin and serving merely to stiffen the body wall. Key Feature Body soft and elongated, with the axis running from mouth to anal end. Many small black-tipped papillae on dorsal surface; brownish in color. Size: Length: up to 46 cm (18 in.) Width: about 5 cm (2 in.) Natural History General natural history: Cucumbers in general have a specialized form of respiration that is unique among the echinoderms. Water is pumped in and out of the anus, distending two great water lungs (respiratory trees) that extend almost the full length of the body. This hollow space at-tracts commensals and parasites. The respiratory tree is the common home of two micro-scopic, one-celled animals, Lichnophora macfarlandi and Boveria sub-cylindrica, each of which clings by means of a ciliated sucking disk at the end of the posterior fleshy stalk. A pea crab may also be found near the posterior end of P. par-vimensis. The scale worm arctonoe pulchra, distinguishable by the dark spot on each scale, often lives commensally on the cucumbers body, along with the crab. Cu-cumbers will actually grow smaller if they don’t find sufficient food. Respiratory trees are the lungs of a sea cucumber. These hollow branched organs lie inside the body cavity on either side of the posterior intestine. The base of the tree connects to a muscular cavity, or cloaca. Circular muscles, or sphincters, close each end of the cloaca. A sea cucumber breathes by expanding the cloaca to draw oxygenated water in through the anus. The posterior sphincter then closes, then cloacal muscles contract to force water up into the respiratory trees. Oxygen is transferred across the thin membrane into the fluids of the body cavity. When the oxygen is depleted, the main body wall contracts to squeeze water out of the trees. The calcareous ring is one of the few obvious, internal hard parts of a sea cucumber. It is comprised of a series of plates, usually 10, joined at the sides like a collar around the esophagus. The tentacle retractor muscles attach to this structure. The plates vary in shape in different species, so the shape of the ring is important in the classification of sea cucumbers. Being one of the few hard structures in a sea cucumber, the calcareous ring is often the only part that fossilizes, thus providing a way of relating extinct and living forms. Warty sea cucumbers and their related species are often called the “earthworms of the sea,” since they cultivate the seafloor in a very similar manner as earthworms cultivate soil. In areas where overfishing has reduced populations of sea cucumbers, the seafloor hardens, therefore destroying habitat for other bottom-dwelling creatures. Members of the genus Stichopus also have an unusual defense mechanism, they can melt, becoming completely limp and eventually disintegrating all together if taken out of the water. If they are not too far gone, they have the ability to reverse the process and recov-er. Predator(s): Predators include sea stars such as Pycnopodia helianthoides, fish, gastropods, and crustaceans as well as humans. Prey: The warty sea cucumber feeds on soft sediments, digesting the organic detritus and small organisms contained within. Feeding behavior: (click on site) Feeding behavior notes Parastichopus parvimensis will lie half buried in the soft substratum, passing through the intestinal tract quantities of sand and mud from which their food is extracted. The feeding tentacles, being part of the water vascular system, are extended and retracted by hydraulic pressure. P. parvimensis has mop-like tentacles, which when pressed onto the substratum pick up particles and transfer them to the mouth. The diges-tive system processes the organic matter, and the bits of shell and sand particles pass through the gut. Seasonal Behavior October-November Seasonal Evisceration Evisceration occurs spontaneously (without human interference) on a seasonal basis in the field. Natural populations have been shown to eviscerate more frequently in November and October. It takes about two to four weeks the viscera to regenerate. November Reproduction Sea Cucumbers have separate sexes, but the sex is often difficult to determine by examin-ing only external features. Reproductive organs of a sea cucumber consist of one or two tufts of tubules in the forepart of the body cavity. They combine into a single duct leading to an external gonopore near the tentacles. Spawning takes place usually in November, and each female can produce many thousands of eggs. P. parvimensis uses an external broadcast spawning method, so fertilization is largely a matter of chance. Environmental cues, such as consecutive sunny days, a plankton bloom, or a certain temperature, can cause a large number of individuals to spawn simultaneously, therefore increasing the chances for successful fertilization. After fertilization takes place, a larva is formed that metamorphoses into a Sea Cucumber, after only a few weeks. Conservation Issues In California, commercial fisheries seek two species of sea cucumbers, warty and Cali-fornia, which are shipped to Asian markets both here and overseas. Commercial fisheries need permits to fish for sea cucumbers, but there are currently no restrictions on the num-ber of animals that can be caught. Many sea cucumber fisheries worldwide have collapsed as a result of overfishing. De-mand for sea cucumbers in Asian markets, where people value them as food and medi-cine, is large. To fill that void, people began fishing for sea cucumbers in waters near the Galapagos Islands, starting in 1988. Then in 2001, the Inter-institutional Management Authority agreed to regulations allowing resident fishermen to catch up to four million sea cucumbers every year, in established fishing zones near the islands.

    almost 5 years ago

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    Adam Curtis commented on "Peltodoris":

    Sea Lemon Genus: Peltodoris Species: nobilis ITIS: 78183 Primary Common Name: Sea lemon Common names (s): Nudibranch, noble dorid, sea slug Synonymous name(s): Diaulula nobilis, Anisodoris nobiis Similar Species: Doris montereyensis General grouping: (pull down on site) Nudibranchs or sea slugs Geographic Range Range description: This species ranges from Alaska, to Islas Coronados, Baja California. Common intertidal-ly in north end of range, subtidally in the south end. Brief range description: (this should always be included in above description) West Coast of North America, from Alaska to Baja California. Habitats (pull down on site) Habitat notes: The sea lemon can be found at depths of up to 230 meters, on pilings, around docks, and in shady areas on rocks below the low tide line. Abundance Relative abundance: Where laminarians or other algae provide the least bit of shelter, the sea lemon, one of the largest nudibranchs, may be commonly found. The sea lemon is common on pilings, such as in the Monterey Harbor. Species Description: The Sea Lemon Peltodoris nobilis, is a bright yellow nudibranch with a white gill-plume, sometimes spotted with light brown or orange. They have background splotches of dark brown or black, and the knoblike tubercle that cover the back are yel-low. Antennae (sensory organs) are comb-like, and short, with a ring of 6 frilly white gills on the back near the rear end. Similarly to some other dorid nudibranchs, especially the yellow ones, Anisodoris has a lemony, persistent, and penetrating odor. This elongate oval nudibranch is one of the largest on the Pacific Coast. Its average length is around 10 cm, but can reach lengths of up to 26 cm, and widths of 7.6 cm. Distinctive features: The sea lemon, when handled, gives off a pungent fruity or lemony smell which is a chemical defense against predators. Key Feature The animal uses a chemical defense system, by producing toxic compounds, which it stores in specialized skin glands. Predators scorn the sea lemons penetrating fruity odor, and acidic taste. Nudibranchs’ bright colors are usually a warning sign to potential preda-tors: eat me at your own risk. Observers have witnessed fish spit out nudibranchs that were accidentally ingested. This could be an evolutionary response descended from ance-stral shelled mollusks that feed on sponges, which developed a tolerance to their quills and chemical deterrents and store them for use in their own defense. The new chemical defense may have given the mollusk its ability to later shed its shell, through the course of further evolution. Size: Length: up to 26 cm (10 in.) Width: up to 7.6 cm (3 in.) Natural History General natural history: This species used to be placed in the genus Anisodoris and was known for a long time as Anisodoris nobilis. Subsequently it was known as Diaulula nobilis. The nudibranch’s bright yellow color is due to the carotenoid pigment carotene, which occurs in many sponges. Nudibranchs in general live for up to one year. Sea lemons breathe through their rosette of gill the back, nudibranchs that have this type of gill arrangement are in a family called dorids. The family name dorid, refers to the Greek mythological character Doris, whose name represents the bounty of the sea. The common name sea lemon probably comes from this animal’s similarity in visual appearance to a lemon based on such qualities as the rough-ened skin, the oval form when seen from above, and the common but not inevitable orange to pale yellow coloration. When handled out of the water, the sea lemon also pro-duces a lemon like odor. The name of the class gastrapoda, means stomach (or muscular) foot, used in locomotion, such as slithering across rocks and sponges. The clade name "nudibranch" comes from the Latin word nudus, meaning naked, and the Greek brankhia, meaning gills. Nudibranchs are often called "sea slugs", which is a misnomer. This has led people to assume that every sea slug is a nudibranch. Nudibranchs are extremely numerous in terms of species, and often very attractive and noticeable, but there is a wide variety of other forms of sea slugs, which belong to several taxonomic groups, not closely related to nu-dibranchs. A number of these other sea slugs are quite colorful, and are sometimes con-fused with nudibranchs. Nudibranchs lack a mantle cavity. They have simple eyes, and are and able to see little more than simple light and dark. Eyes are set into the body, are about a quarter of a mil-limeter in diameter, and consist of five photoreceptors forming a lens. Nudibranchs have cephalic (head) tentacles, which are sensitive to touch, taste, and smell, and club shaped rhinophores to detect odors, but gastropods have no hearing. Predator(s): Like other nudibranchs, they have few or no predators because of their foul taste, but might occasionally become a meal to fish or other nudibranchs. Prey: The sea lemon primarily feeds on a wide variety of sponges. They also occasionally feed on dead organic matter (detritus), bryozoans, tunicates, other nudibranchs. Feeding behavior: (click on site) Feeding behavior notes This species does not have a radula, yet it feeds on several species of sponges. Its favorite prey is the breadcrumb sponge. A nudibranch’s color often matches the color of the sponge it eats.The animal first macerates its food and then sucks out soft tissue, apparent-ly avoiding the sponge spicules, which have not been found in its gut. Studies of sea lem-ons in Pacific Grove, show that individual nudibranchs are quite conservative in their food habits, and they tend to keep on eating the same food species, even if they are trans-ferred to other sites. Seasonal Behavior November-March Reproduction A sea lemon, like all nudibranchs, can produce both sperm and eggs (it’s hermaphroditic), who mutually copulate. Since nudibranchs live for only about one year, their ability to mate with other nudibranchs increases their chances of reproducing. Females lay circular, elaborate, light yellow ribbons containing as many as 2,000,000 eggs; only 99% of the resulting larvae survive. The ribbon is attached in a coil by one edge to a hard substrate. Egg masses exposed to the light have higher mortality rates. Eggs hatch in 20-25 days, trochophore larvae settle within about 2 hours of hatching. In the Monterey Bay, the typical spawning season is from November to March. Conservation Issues The sea lemon is widely used in neurophysiological research, because they have large cell bodies in their neurons. Single brain cells and neurotransmitters can be studied, such as receptors for serotonin, dopamine, nitric oxide etc. Sea lemons are abundant now, and should stay abundant if we protect their ecosystem. The sea lemon is currently not on the IUCN Red list of threatened species.

    almost 5 years ago

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    Adam Curtis commented on "Styela montereyensis (Dall, 1872)":

    Stalked Tunicate Genus: Styela Species: Montereyensis ITIS: 159318 Primary Common Name: Stalked tunicate Common names (s): Long-Stalked Sea squirt, Monterey stalked tunicate Synonymous name(s): Cynthia montereyensis, Tethyum montereyensis Similar Species: Styela clava General grouping: (pull down on site) Sea squirts Geographic Range Range description: The stalked tunicate can be found north to Ucluelet (Vancouver Island) and Hope Island (British Columbia), and south to Isla San Geronimo (Baja California). Brief range description: (this should always be included in above description) Vancouver Island to Baja California. Habitats (pull down on site) Habitat notes: Stalked tunicates can be found fairly commonly, attached firmly to solid substrata in calm to rough waters. They are found in shallow water areas where there are tidal currents. In the Pacific Northwest stalked tunicates are found primarily in outer straits and the open coast, but are rare in inland waters. S. montereyensis, can be found in depths ranging from the low intertidal zone, to about 30m. Abundance Relative abundance: The sea squirt is locally common year round. It is an easily recognized and broadly dis-tributed solitary tunicate. Where it occurs at all, the stalked tunicate may be present in relatively large numbers, but in small densities. Species Description: The stalked tunicate, Styela montereyensis has a cylindrical and elongate body, supported on a thinner stalk about equal to the body length. Overall length occa-sionally exceeds 25 cm in calm habitats but more often 8-15 cm in exposed sites. The stalked tunicate has a tough, leathery tunic with prominent longitudinal ridges and grooves running across the entire length of the animal, but otherwise relatively smooth. Stalked tunicates are yellow to dark reddish brown, and often fouled with other organ-isms and debris in harbors, but clean in wave swept areas. Distinctive features: Although they just look just like slimy sacs, sea squirts are more closely related to humans than any other invertebrate group, because larval tunicates have several chordate structures, including a notochord and a nerve chord. Later these are lost, in most adult forms. There are two openings are found on the tunicate: the buccal siphon and the atrial siphon. Sea squirts get their name because a gentle squeeze causes water to shoot out of the atrial siphon. Sedentary adult forms can either be colonial or solitary. Tunicates have a long, tubular heart which contracts in two directions. The species may store vanadium in its tunic, about 36-40 ppm. Key Feature S. montereyensis can be distinguished from similar species of tunicates, be-cause its siphons are close together at distal end; the oral siphon is re-curved (pointing to the side or downward) and the atrial siphon is straight (pointing upward). Size: Height: up to 25 cm (10 in.) Width: 5 cm (2 in.) Natural History General natural history: Despite bearing aragonite spicules, the fossil record of the sea squirts is largely lacking, and is only available from as far back as the Silurian period. Over the past few hundred years, the world's harbors have been invaded by non-native sea squirts, which have clung to ship hulls, or introduced other organisms such as oysters and seaweed. Several factors, such as a lack of predators, quick attainment of sexual maturity, and tolerance to a wide range of environments, allows sea squirt populations to grow quickly. Unwanted popula-tions on docks, ship hulls, and farmed shellfish, cause economic problems. Sea squirt in-vasions have disrupted the ecosystem of several natural subtidal areas by smothering na-tive animal species. Blood is pumped throughout the body, by a short tubular heart. For about 100 beats the blood flows in one direction, then after a short pause it starts flowing in the opposite di-rection. Tunicate blood has very high levelst of heavy metals, especially vanadium and iron, possibly to help deter predators. Gas exchange occurs through the body wall. There is no head, nervous system, and sensory organs are highly underdeveloped, but adequate for the sessile life style. Although the lifespan of stalked tunicates is unknown, observed specimens have lived for at least 3 years. Ascidian tunics are composed mostly of an acellular (not made of cells) tunicin matrix, similar to cellulose. There are some living cells of different varieties within this matrix but they are well spaced out. Usually, the tunic is attached to the substrate by a small holdfast and stands upright. It has two openings, an inhalant siphon and an exhalent siphon. On the inner surface of the tunic is a thin epidermis, which secretes the tunic. Inside of the epidermis is a thicker dermis, and then bands of longitudinal and circular muscle, these muscles squeeze the tunic, causing a jet of water to leave the exhalent siphon. This action may help deter predators. Stalked tunicates can become overgrown with growths of anemones, hydroids, and even other tunicates. Predator(s): Sea squirts are the natural prey of many animals, including nudibranchs, flatworms, mol-lusks, sea stars, rock crabs, birds, fish, and sea otters. Sea squirts are also eaten by humans in many parts of the world, including Korea, Japan, Europe, and Chile (where they are sold under the name “sea violet”). Prey: Various small particles filtered from the water, such as plankton. Feeding behavior: (click on site) Feeding behavior notes S. montereyensis has a branchial basket, which it uses as its way to construct a filter-feeding net out of mucus. The branchial basket supports the net and cilia on the edges of the gill slits, pulling water through it, helping the animal collect food. Sea squirts feed by taking water through their oral siphon. The water enters the mouth and pharynx, and then flows through mucus-covered gill slits, to a water chamber called the atrium, finally exiting through the atrial siphon. Water currents are maintained by hundreds of beating cilia, but can also be regulated by muscles. Reproduction Nearly all sea squirts are hermaphrodites. Larval settlement and breeding, occur in the summer. Studies of developing eggs, have shown that the inner follicle of the oocyte, provides the test cells, which are enclosed with the ovum inside the chorion. Both sperm and eggs are shed to the sea. In natural situations, larvae settle best on surfaces which have been underwater, for at least several months. In metamorphosing larvae, the tail col-lapses as this is characteristic for members of the suborder Stolidobranchia. Conservation Issues The exceptional filtering capability of adult sea squirts causes them to accumulate pollu-tants that may be toxic to embryos and larvae as well as impede enzyme function in adult tissues. This property has made them a sensitive indicator species of pollution. Sea squirts are valuable because of their unique evolutionary position; as an approximation of ancestral chordates, they can provide valuable information regarding chordate evolution. To deter predators, tunicates secrete various chemicals that are of pharmacological inter-est. Yondelis, a drug that was recently approved, was developed from tunicates to treat soft tissue sarcoma. Tunicates also transport carbon to the sea floor, in turn slowing the effects of global climate change.

    almost 5 years ago

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    Adam Curtis commented on "Pagurus samuelis (Stimpson, 1857)":

    ITIS: 97787 Primary Common Name: Blueband hermit crab Common names (s): Hermit crab, blueband hermit Similar Species: P. granosimanus, P. hemphilli General grouping: (pull down oemphilli, n site) Crabs, barnacles, shrimp, lobster Geographic Range Range description: P. samuelis can be found as far north as Alaska, and as far south as Punta Eugenia (Baja California). Brief range description: (this should always be included in above description) Alaska to Baja California Habitats (pull down on site) Habitat notes: High intertidal to subtidal; rocky intertidal along the outer coast, not often found in inland seas. Abundance Relative abundance: P. samuelis is abundant along rocky coasts, in mid to lower tidepools, and found occasionally on coarse substrates in bays. One of the most common intertidal her-mit crabs on the outer coast, and upper tide pools, especially in southern and central Cali-fornia. Species Description: The blueband hermit crab Pagarus samuelis has red antennae, and is orange or banded. Walking legs have bright blue bands, but smaller crabs have white bands. The body and claw color is brown or green, with a triangular rostrum, chelae with tubercles, and a hard carapace longer than it is wide. The legs and carapace are hairy with setae. The carapace can reach widths of up to 19 mm, and a total length of about 4 cm., Hermit crabs are decapods, just like all crabs. Decapods have five pairs of legs, including one pair of claws. One claw is much larger than the other, which the hermit crab uses for defense and shredding its food. It uses the smaller claw to eat with. The third and second pairs of legs help the crab to walk, and the other two pairs hold the hermit crab within its shell. Distinctive features: P. samuelis is often more willing than other hermit crab species to stick its legs out of its shell to try and escape. This species is especially active in the evening and at night. Key Feature P. samuelis seems to have a strong preference for Chlorostroma (tegula) funebralis shells, which they steal from one another, to use for protection, but they don’t seem to kill funebralis to get their shells. Size: Carapace length: up to 19 mm (0.75 in.) Total length: up to 4 cm (1.6 in.) Natural History General natural history: Hermit crabs spend much of their time and energy finding and retaining their snail shell resource. Competition for shells is related with complex behavioral signaling. Dominance among species and by larger crabs over smaller individuals has been noted frequently. Some species of hermit crabs have strong preferences for certain species of snail shells, such as P. Samuelis preference for Chlorostroma (tegula) funebra-lis shells, while others may be more concerned with size of the shell. Further study of the kinds of snail shells that hermit crabs occupy, how they fit, and the relative sizes of the hermits and their shells is needed to increase our understanding of the use of their li-mited shell resource. It is not known, if hermit crabs simply wait for snails to die, to take their shells, or if they obtain a meal and a new home all with one stroke. However, an experiment using P. Samuelis and the preferred Chlorostroma (Tegula) funebralis snails, attacks by the hermit crab were observed, but the snail would saw the rough edge of its shell back and forth across the hermit’s claw, convincing the hermit that this shell was unavailable. Dry funebralis shells have a grayish color that blends very well with the dry rocks, providing camouflage to the hermit crab. Among themselves, when not busy reproducing or scavenging, the gregarious hermit crabs fight cautiously but tirelessly, over each other’s shells. Most often they are able to retreat into their shells, if both parties have a shell. If an individual gets out of its shell and doesn’t get into another one, the other crabs will cannibalize it, eating the soft abdomen flesh. Adult populations of P. samuelis are rather inactive during the day, but ac-tivity levels pick up in the late afternoon, and continue through the night until dawn. This activity pattern seems to be a direct response to light levels, not simply an inherent rhythm of behavior. The compound eyes can adapt to day and night conditions by shifts in the position of pigments, as direct by response to light levels. Relative growth techniques are useful in maturation studies. The relative size of claws is an aid to recognition of social systems. Males with the largest claws are generally domi-nant. Males of different sizes and claw development, may adopt very different behavioral reproduction strategies. Discontinuity of growth is one of the primary aspects of the lives of arthropods. Ecdysis, is the process of shedding the old layer of skin called the exuvia. The additional increase in size only takes a few minutes. However, the total interval be-tween molts represents a dynamic, cyclical process. Following ecdysis the animal is very soft, until its cuticle gradually hardens as different areas of the exoskeleton calcify suc-cessively. Before its new shell hardens, the crab absorbs water, expanding to a size larger than before the molting process. The premolt period, is signaled by the separation of the epidermis from the cuticle. A mi-totic burst precedes the deposition of new cuticualr structures, expanding the number of epidermis cells. First the new setae are organized using the previous cuticle as a template. After new setae are organized, pre-exuvial layers are secreted over the general surface of the body. Molting is imminent if the epimeral suture of the crab is visibly split. Exuviae can be distinguished from the empty remains of a dead animal by the absence of pigment from the corneas of the eyestalks of the exuvia. Discovery of a fragile intact ex-uvia suggests that a soft, recently molted crab may be hiding nearby. The previous owner of the exuvia can by certified by matching details of the pigment patterns of the exuvia, to the soft animal. Comparison of the soft animal and its exuvia demonstrates the growth increment per molt for animals of that size. Decapods are able to cast off (autotomize) their limbs under duress and then regenerate the appendages at subsequent molts. Autotomy is readily demonstrated by squeezing bas-al segments of an appendage. A specific muscle is stimulated that slices through a cuticu-lar apodeme, severing the limb. This is a highly ordered process. The autotomized limb is always severed at a preformed breakage plane. Upon autotomy, a flap of skin closes over the severed limb base so that scarcely a drop of blood is lost. The regenerating limb forms in a bud that protrudes from the stump of the autotomized limb. Recently regenerated appendages are smaller than normal limbs, but this size discrepancy is no longer apparent after a second or third molt. Predator(s): Pile perch, sheephead, and spotted kelpfish Prey: Adults scavenge algae, especially Macrocystis pyrifera and dead animal mat-ter. Feeding behavior: (click on site) Feeding behavior notes The diet of P. samuelsis is varied; adults scavenge both plant materials (especially pieces of the large brown algae Macrocystis and Silvetia) and dead animal matter. They have been kept indefinitely in the lab on a diet of Pelvetia canaliculata. Seasonal Behavior June-July Reproduction Sexual maturity occurs early in life; the smallest ovigerous females, measuring only 1.8 mm across the carapace shield, carry less than 100 eggs; large females may carry more than 2,000 eggs. Upon reaching sexual maturity, most if not all decapods undergo a molt of puberty to attain their adult morphology. Sizes are similar for both sexes of hermit crab. During courtship, males grasp the female's shell, and carry her around for a day or longer, occasionally knocking his shell against hers repeatedly. Mating is brief, only last-ing a few seconds, because both animals must nearly leave their shells to mate. Eggs are carried on the female’s abdomen, a region always protected by the shell, but provided with a continuous current of water for aeration by the action of abdominal ap-pendages. Ovaries of decapod crustaceans lie dorsal to the other organs in the carapace and anterior part of the abdomen. Within a day, an outer membrane forms around each egg and a thin strand attaches it to pleopodal setae. Young eggs are evenly pigmented. As the yolk is gradually displaced by the growing embryo, a transparent area appears in the egg; in advanced embryos, eyespots and larval chromatophores may also be recognized. Broods about to hatch often have a grayish cast since all the brightly colored yolk has been absorbed. The eggs hatch as larval zoea. There are four zoeal stages, lasting 26-30 days. Under lab conditions, larvae thrive on a diet of brine shrimp larvae. The fourth zoeal instar molts to a glaucothoe larval stage that settles from the plankton, later finding a tiny empty shell, it begins to feed on organic materials scraped from stones. After several days it molts, becoming a tiny juvenile hermit crab. Conservation Issues Hermit crabs are abundant in tide pools, but if you visit tide pools, it’s important to follow proper tide pool etiquette. Look, but don’t collect or disturb, which is illegal at many locations. The number of empty shells in a tide pool helps ensure the survival of hermit crabs, so please leave all empty shells where you find them.

    almost 5 years ago

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    Adam Curtis commented on "Metridium farcimen (Tilesius, 1809)":

    Giant Plumose Anemone Genus: Metridium Species: farcimen ITIS: 611773 Primary Common Name: Giant plumed anemone Common names (s): Plumose anemone, Metridium Synonymous name(s): Metridium giganteum Similar Species: Metridium senile (Metridium dianthus) General grouping: (pull down on site) Corals and anemones Geographic Range Range description: The Plumose anemone ranges from Alaska to southern California and along both sides of North America. Brief range description: (this should always be included in above description) Alaska to southern California Habitats (pull down on site) Habitat notes: M. farcimen can be found in both subtidal and low intertidal zones, including jetties, wharfs, harbours, breakwaters and floats. When found on wharfs, anemone communities of dense distribution are common. Larger specimens are often found solitarily in the subtidal. Found on pilings and docks in bays and on rocks and shells on the outer coast, down to a few hundred meters depth. Abundance Relative abundance: In a study of species abundance in Alaska, M. farcimen was the most commonly observed macro-invertebrate species and typically occurred on boulders, high-relief rock, and rock pavement, often in association with Primnoa spp. Species Description: The Giant plumose anemone, Metridium farcimen, is typically large, solitary, and subtidal. Oral disk is lobed and covered with short tentacles that may number in the hundreds; commonly white, uncommonly salmon, brown, or speckled. The species name farcimen, refers to its sausage-like appearance, as “farcimen” means; with stuffing or sausage. Subtidal animals can often reach 25cm in crown diameter and 50cm in height. However larger specimens have been reported up to a meter in height. Shape of the column is much longer than wide. Tentacles lining the mouth of the oral disk are quite fine, very numerous, slender and short. Tentacle coloration is typically transparent when the tentacles are expanded and take the color of the column when contracted. Distinctive features: Anemones are rich in nematocysts (stinging cells) which are used in both defense and attack. The normal tentacles contain these cells used for both defense and feeding. However, in large colonies of Plumose Anemones the species bordering the colony develop a different type of tentacle; "catch" tentacles. These tentacles, which are used to repel non-cloned anemones, take about 9 weeks to develop close to the mouth and may number as great as 19 on an individual organism. If the "catch" tentacles, which contain a different type of nematocysts, touch another anenome from a separate colony a stinging tip breaks of and releases the separate complement of nematocysts. This technique is used to repel intruding anemones. Interestingly, these tentacles can expand to a possible length of 12cm. Key Feature Large to one meter tall with lobed oral disc fringed with short fine tentacles; usually white but may be pinkish or tan-brown. Size: Height: up to 1 m (40 in.) Crown diameter: up to 25 cm (10 in.) Natural History General natural history: The animals generally appear motionless, but time-lapse movies show slow rhythms of expansion and contraction. The body can assume a wide variety of shapes. As in other anemones, the fluid in the gut, under positive pressure from the muscles of the body wall, act as a hydraulic skeleton, providing internal support. Additional support, along with elasticity and extensibility, is provided by the mesoglea or middle of the body wall, which contains an amorphous polymer network of collagen. An anemone crawls slowly along the substratum by muscular waves at its base. This distinctive large, solitary, subtidal species that lives on pilings in bays and on rocks and shells off the coast was once considered to be an ecotype of M. senile. Unlike regular feeding tentacles, catch tentacles have a complement of nematocysts, and as many as 19 may be present in a single anemone. These tentacles are capable of great expansion, and can stretch over 12 cm to explore their surroundings, extending and retracting rhythmically. But the catch tentacles don’t respond to food or clonemates, but if even a regular feeding tentacle of metridium makes contact with another anemone or non-clonemate, it sticks and stings and the stinging tips break off. The attacked individual may contract, bend, or move away, and after some time, tissue damage can be seen at the site of the clinging tentacle tip. Anemones in the center of a clone usually bear no catch tentacles, as these develop in a period of about 9 weeks if moved out to the border of the clone, or otherwise placed in contact with non clonemates. When a border metridium armed with catch tentacles encounters a green anemone, it may lash it repeatedly, causing it to contract or move away. The catch tentacles are clearly used for aggression against non clonemates and anemones of other species. Plumose Anemone symbiosis is an area in which little research has been done. Possible commensal behaviour may be similar to other anemones which have certain fish (e.g Clown Fish) which use the anemone. Related to corals and jellyfish, metridium anemones are part of the Phylum Cnidaria. They all have in common a feeding method that uses specialized stinging cells in their tentacles to stun and capture their prey. Scientists believe that metridium’s broad plumes form current eddies that aid in their feeding. Predator(s): The Plumose Anemone has few predators. Nudibranchs feed on small anenomes, while in Puget Sound (Washington State) a sea star Dermasterias imbricata has been found to feed on larger anemones. Prey: Both the small and large anemones feed primarily on zooplankton, using their stinging tentacles to catch the prey. The feeding appears non-selective. Scraps of fish, squid and small benthic (subtidal) organisms are also taken. Feeding behavior notes These sea anemones are sit-and-wait predators, voracious ones at that if you are living in the plankton. They all have in common a feeding method that uses specialized stinging cells in their tentacles to stun and capture their prey. Scientists believe that metridium’s broad plumes form currents and eddies that aid in their feeding. Reproduction The anemone reproduces both asexually and sexually. Asexual reproduction occurs as the anemone moves about, leaving small sections of its pedal disk (base) behind, in a process described as pedal laceration. Dense colonies can be formed in this manner, with the pedal disks forming small cloned rounded anemones that feed and grow. Sexual reproduction occurs in a broadcast spawning process whereby the males release sperm with wedged-shaped heads stimulating the females to release their eggs, about 0.1mm in diameter with a pinkish colouration. External fertilization occurs, with the zygote dividing to form a planula larva which swims in planktonic form. Planulae settle and metamorphose into young anemones Conservation Issues M. farcimen cannot survive where there is industrial pollution, sewage, sludge, or anoxic conditions, although they may tolerate high levels of pollution from boats and harbors. M. farcimen provides habitat for several commercially important groundfishes and have been identified as habitat areas of particular concern by the North Pacific Fishery Management Council.

    almost 5 years ago • edited: about 3 years ago