Morphology
The body structure of these animals is a thin-walled, cylindrical, vase-shaped tube with a large central atrium. The body is composed entirely of silica in the form of 6-pointed siliceous spicules, which is why they are commonly known as glass sponges. The spicules are composed of 3 perpendicular rays giving them 6 points. Spicules are microscopic, pin-like structures within the sponge’s tissues that provide structural support for the sponge. It is the combination of spicule forms within a sponge’s tissues that helps identify the species.In the case of glass sponges the spicules 'weave' together to form a very fine mesh which gives the sponge’s body a rigidity not found in other sponge species and allows glass sponges to survive at great depths in the water column. Overlying the spicule framework there is more siliceous tissue called a syncytium which forms very fine fibres which look rather like a cobweb over the framework. The syncytium means that the sponge has a mass of tissue with no defined cell boundaries but lots of nuclei.The top end of the sponge has a sieve-like disc over the end and the sponge is anchored to the substrate by means of fine, hair-like fibres. These fibres are between 50 and 175mm long. Recent research has proved that these fibres have the same composition as fibre-optical cables like those used in modern telecommunications. They can trap and transmit light. There are several theories about why the sponge does this. One is to attract symbiotic algae or as an attractant for the shrimp which lives within the sponge’s body cavity. Neither of these has been proved and it may just be a coincidental by-product of the spicules’ purity.While alive, the tissue of these sponges is white to creamy yellow, depending upon how much particulate material they have accumulated in their tissues. The dry 'skeleton' seen in museum collections has often been bleached to create the pure white colour.

New sub species
In 2008, Dr Konstantin Tabachnick, a well regarded researcher on this sponge group, and his co-authors, designated 4 new subspecies of Euplectella aspergillum:

• E. aspergillum regalis (formerly E. regalis Schulze),
• E. aspergillum australicum
• E. aspergillum indonesicum
• E. aspergillum aspergillum.

These were all collected from around the coast of Australia.Some researchers consider the Hexactinellida sufficiently different from the other sponge groups to require their own Phylum - Sympagla

Euplectella aspergillum or Venus' flower baskets are deep sea animals. They are known as glass sponges as their bodies are entirely composed of silica. The body structure of these animals is a tube that:

• is thin-walled
• is cylindrical
• is vase-shaped
• has a large central atrium

Glass sponges occur worldwide, predominantly at depths between 10 and 1000 metres (20-3,300 feet) where the water is very cold and the levels of silica are high.Euplectella species are found in the deep Southern Pacific around the coast of Japan and Philippines and more recently new species have been found off Australia.

Euplectella aspergillum Venus flower basket was first described by Sir Richard Owen, in 1841 in the Transactions of the Zoological Society.Sir Richard Owen was the first Director of the Natural History Museum when it moved to South Kensington and the man who coined the term “dinosaur”.

Type specimen
The type specimen of the sponge was actually collected by Hugh Cuming, one of the leading conchologists of his day, whose collection was purchased by the Museum in 1866, at some time during his voyage to the Philippine Islands (1836-1840). Unfortunately Cuming’s journals for this voyage were lost and so we can only hazard a guess as to when the specimen was collected.In a letter Cuming wrote to Owen from Manila on 1 November 1837, he said…” I trust you will be pleased with my labours, don’t say I have been idle. I have now collected 1809 species of shells, 1900 do [ditto] plants, you know the rest, all in 13 months work…” So it seems possible that the sponge was collected during this period

This sponge species is found in the western Pacific Ocean near the Philippine Islands. Other species in this genus are found in oceans all around the world (Bayer and Owre 1968; Pearse and Buchsbaum 1987; Britannica.com 1999-2000).

Biogeographic Regions: pacific ocean (Native )

Eastern Philippines, Philippines

Habitat
Glass sponges are deep sea marine animals. There are no records of this group of sponges being found in freshwater. These sponges

• live at depths between 10 and 1000 metres (20-3,300 feet)
• require a solid substrate such as rocks to attach to
• occur at depths where the water is very cold (2-11^o C or 32-52^o F)
• are found in water with high levels of dissolved silica

Global distribution
Glass sponges occur worldwide, predominantly at depths between 10 and 1000 metres (20 -3,300 feet). Although they are more abundant and diverse in shallower depths of polar regions.Euplectella Species are found in the deep Southern Pacific around the coast of Japan and Philippines and more recently new species have been found off Australia.

Hexactinellida Species are the oldest multi-cellular animals found in the fossil record. Spicules have been found in Mongolia and China which have been dated to the Late Proterozoic (2500 to 542.0 ± 1.0 million years ago). The Hexactinellida are thought to have reached their maximum diversity during the Cretaceous (99.6 – 65.5 million years ago), when these sponges formed the vast reefs of the Tethys Sea. These reefs can now be found as stony outcrops from southern Spain through France, Germany, and Poland all the way to Romania.

E. aspergillum is radially symmetric and of moderate size, ranging from 7.5cm up to 1.3m in height. The majority are between 10cm and 30cm tall. The skeleton contains hexactine (six-rayed) siliceous spicules and in addition contains a latticework of fused siliceous spicules. This is where is gets the name "glass sponge" because quite literally it is made of glass, making it the most exquisite example of the class Hexactinellida, but also as precarious and as brittle as glass can be. Surrounding this beautiful skeleton is a net of living tissue called a trabecular net, which is created by the fusion of amoeboid cells called archaeocytes. Within this trabecular net are elongated, finger-like chambers covered in choanocytes, which open into the spongocoel. Choanocytes are another class of cells, they have whip-like flagella that they vibrate in order to move water through the sponge. Both the external and internal surfaces are covered by this trabecular net. The chambers throughout the body are irregular. The end result is a funnel or vase-like shape. Hence the name, 'Venus's-Flower-Basket.' At its base, E. aspergillum has a tuft of elongated spicules that attaches it to the ocean bottom (Buchsbaum and Pearse, 1987; Hickman, Roberts, and Larson 1997; Kaestner 1967).

This species is found attached to rocky areas of the seafloor. It is found from 100 to 1000 m below the surface, and is most common at depths greater than 500 m (Bayer and Owre, 1968; Coleman 1991; Pearse and Buchsbaum, 1987).

Aquatic Biomes: benthic ; coastal

Depth range based on 14 specimens in 2 taxa.
Water temperature and chemistry ranges based on 10 samples.

Environmental ranges
  Depth range (m): 188 - 445
  Temperature range (°C): 9.783 - 12.877
  Nitrate (umol/L): 17.740 - 27.236
  Salinity (PPS): 34.600 - 34.924
  Oxygen (ml/l): 2.337 - 3.554
  Phosphate (umol/l): 1.535 - 1.817
  Silicate (umol/l): 27.363 - 41.318

Graphical representation

Depth range (m): 188 - 445

Temperature range (°C): 9.783 - 12.877

Nitrate (umol/L): 17.740 - 27.236

Salinity (PPS): 34.600 - 34.924

Oxygen (ml/l): 2.337 - 3.554

Phosphate (umol/l): 1.535 - 1.817

Silicate (umol/l): 27.363 - 41.318
 
Note: this information has not been validated. Check this *note*. Your feedback is most welcome.

E. aspergillum's staple food is microscopic organisms and organic debris. These are filtered out of the water that flows through the sponge. (Britannica.com, 1999-2000).

Sponges are individual animals not colonial like corals.

Diet
Sponges are filter feeders. They create a current to draw water in through their tissues and filter out any small particles of food.

Reproduction
No one is really sure if these sponges have a defined breeding season as such because they live in such deep water. Other sponge species are influenced by the seasons and the phases of the moon. Hexactinellid sponges are viviparous. Eggs develop into larvae within the sponge and then these motile larvae are released into the water current. The larvae have a band of hairs (cilia) which enable them to propel themselves through the water. Laboratory studies of another species of glass sponge have shown that the while the larvae are capable of swimming for several days in fact they tend to settle after only about 12 hours before developing into juvenile forms of the adult.

"Little is known about their reproduction". Details of reproduction of E. aspergillum are not known, therefore we can only explain the normal forms of reproduction in Porifera in general. Many times when unfavorable conditions occur sponges will resort to asexual reproduction. In marine sponges using asexual reproduction, amoebocytes attach themselves around the deteriorating sponge. Later epithelial cells surround the amoebocytes, and when the deteriorating sponge is all gone a new animal grows from the clump of cells. Some sponges have two sexes, and individuals have only one sex, but it is likely that E. aspergillum is hermaphroditic, producing both male and female gametes at different times. Archaeocytes and choanocytes have both been observed maturing into gametes, and these maturations are similar to those found in higher animals. Sperm enter the sponge through the inhalant current and then fertilize the ova. A carrier cell, an amoebocyte, effects fertilization of the ovum so that not just sperm and ova are involved. Then the carrier cell and the sperm both reach the ovum, and form a cytostome, which engulfs both the carrier cell and sperm. This zygote then goes through radial holoblastic cleavage forming cells all similar in size and shape. Then the embryo forms a free-swimming larva, which eventually develops into the new sponge.

Light-transmitting fibers: Venus flower basket
 

The glass-like fibers of a glass sponge transmit light better than our fiber optics, yet are made from natural materials and at ambient temperatures.

     
  "The thin glassy fibers protruding from the base of the Venus flower basket sponge are better able to transmit light than industrial fiber optic cables used for telecommunication. Additionally, the sponge's fibers are more flexible than the man-made variety. The sponge produces its fibers at low temperatures using natural materials. Trace amounts of sodium are added to the fibers to increase their ability to conduct light. The high temperature required for the manufacture of industrial fiber optics precludes additives such as sodium, and yields a fiber that is brittle and easily broken. Scientists hope, however, to mimic the Venus flower basket's fiber manufacture process, developing a way to produce fiber optics at ambient temperatures." (Courtesy of the Biomimicry Guild)
  Learn more about this functional adaptation.

Siliceous skeleton provides support: Venus flower basket
 

Skeleton of sponge provides strength with lightweight material via its siliceous composition.

   
  "Despite its inherent mechanical fragility, silica is widely used as a skeletal material in a great diversity of organisms ranging from diatoms and radiolaria to sponges and higher plants. In addition to their micro- and nanoscale structural regularity, many of these hard tissues form complex hierarchically ordered composites. One such example is found in the siliceous skeletal system of the Western Pacific hexactinellid sponge, Euplectella aspergillum. In this species, the skeleton comprises an elaborate cylindrical lattice-like structure with at least six hierarchical levels spanning the length scale from nanometers to centimeters. The basic building blocks are laminated skeletal elements (spicules) that consist of a central proteinaceous axial filament surrounded by alternating concentric domains of consolidated silica nanoparticles and organic interlayers. Two intersecting grids of non-planar cruciform spicules define a locally quadrate, globally cylindrical skeletal lattice that provides the framework onto which other skeletal constituents are deposited. The grids are supported by bundles of spicules that form vertical, horizontal and diagonally ordered struts. The overall cylindrical lattice is capped at its upper end by a terminal sieve plate and rooted into the sea floor at its base by a flexible cluster of barbed fibrillar anchor spicules. External diagonally oriented spiral ridges that extend perpendicular to the surface further strengthen the lattice. A secondarily deposited laminated silica matrix that cements the structure together additionally reinforces the resulting skeletal mass. The mechanical consequences of each of these various levels of structural complexity are discussed." (Weaver et al. 2007:93)
  Learn more about this functional adaptation.

Filter feeding moves water: Venus flower basket
 

Filter feeding mechanism of sponge moves water through body by intaking low and releasing high.

   
  "A sponge takes in water at its base, filtering the food from it and expelling it through holes higher up." (Courtesy of the Biomimicry Guild)
  Learn more about this functional adaptation.

Through researching this invertebrate animal, and not finding a great deal of information I have come to the conclusion that since E. aspergillum is found at such great depths, the status of its population is not known.

US Federal List: no special status

CITES: no special status

No adverse affects recorded.

No positive benefits recorded.

Significance for peopleIn some Asian cultures, like Japan these sponges are given as good luck charms, like horseshoes, to couples getting married as they often have two tiny shrimps living in symbiosis inside the sponge’s body cavity, always a male and a female. They swim in as larvae and then get trapped inside the sponge’s mesh-like tissues as they grow to adults. They are perfectly happy though as they feed off the filtered food debris left by the sponge! Any young can escape from the sponge as they are small enough to swim through the mesh of the sponge’s tissue and can move to find their own sponge as a home.Many people may well have encountered these cleaned and dried “skeletons” of these sponges in an art class or seen them in a Victorian glass dome display as they have always been popular for their delicate beauty. Occasionally it is used in marine aquaria.