╳ Venus’ Flower Basket is simply divine. Euplectella aspergillum or Venus' Flower Baskets are inhabitants of the deep. They are known as ‘glass’ sponges because their bodies are entirely composed of silica. The body structure of these animals is a tube that is thin-walled, cylindrical and vase-shaped with a large central atrium. Glass sponges occur worldwide, predominantly at depths between 10 and 1000 metres 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. ╳ This ephemeral creature, was first described by Richard Owen, the first Director of the Natural History Museum when it moved to South Kensington, in 1841 in ‘The Transactions of the Zoological Society’. (Interestingly, he is also the man who coined the term ‘dinosaur’.) Euplectella aspergillum’s 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 and 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 them 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 and 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 living, the tissue of these sponges is a white to creamy yellow, depending upon how much particulate material they have accumulated in their tissues and the dry 'skeleton' seen in museum collections has often been bleached to create the pure white colour. ╳ When the Venus’ Flower Basket is small, tiny shrimp swim in and out of it, however, as it grows it seals off the open upper end, and at the same time the shrimps grow so that they cannot swim through its side. As this happens, a pair of shrimps, one male and one female, will become trapped and spend the rest of their lives inside. To the Japanese this is a symbol of eternal love and being happily married forever therefore a Venus’ Flower Basket is sometimes given as a wedding present in Japan because of this beautiful symbolism.
