Hexactinellids or glass sponges are estimated to live up to 15,000 years! They produce extremely large spicules (glass-like structural particles made of silica) that fuse together in beautiful patterns to form a “glass house”; a complex skeleton that often remains intact even after the sponge itself dies. Found in all oceans of the world, they are particularly common in Antarctic waters. The most famous species is Euplectella or the “Venus flower basket” which builds its skeleton in a way that entraps Spongicolid shrimp that live the rest of their lives trapped inside the sponge, mating and releasing their young into this trapped world.
Glass sponges are relatively uncommon and are mostly found at depths from 450 to 900 metres (1,480 to 2,950 ft) below the sea level. Although the species Oopsacas minuta has been found in shallow water, others have been found much deeper. They are found in all oceans of the world, although they are particularly common in Antarctic and Northern Pacific waters.
They are more-or-less cup-shaped animals, ranging from 10 to 30 centimetres (3.9 to 11.8 in) in height, with sturdy lattice-like internal skeletons made up of fused spicules of silica. The body is relatively symmetrical, with a large central cavity that, in many species, opens to the outside through a sieve formed from the skeleton. Some species of glass sponges are capable of fusing together to create reefs or bioherms. They are generally pale in colour, ranging from white to orange.
Much of the body is composed of syncitial tissue, extensive regions of multinucleate cytoplasm. In particular, the epidermal cells characteristic of other sponges are absent, being replaced by a syncitial net of amoebocytes, through which the spicules penetrate. Unlike other sponges, they do not possess the ability to contract.
Their body also consists of three parts in total: the inner and outer peripheral trabecular networks, and finally, the choanosome, which is used for feeding purposes. The choanosome acts as the mouth for the sponge while the inner and outer canals that meet at the choanosome are passages for the food creating a consumption path for the sponge.
All hexactinellids have the potential to grow to different sizes, but the average maximum growth is estimated to be roughly around 32 centimeters long. Some even grow past that length and continue to extend their length up to 1 meter long. Estimated life expectancy for hexactinellids that grow around 1 meter is approximately around 200 years (Plyes).
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