St. Nicholas/Volume 40/Number 1/Nature and Science/Glassy Sponge

A Sponge of Glassy Material

The interlacing fibers of one end of the Venus flower-basket.

Our young people are undoubtedly familiar with the fact that the sponge, as we ordinarily know it, is in reality the flexible skeleton of a colony of salt-water animals.
Nearly the entire length of a “glass-sponge,” known as Venus Flower-basket.
(Euplectella aspergillum.)

The Venus flower-basket, a favorite and beautiful object found in many natural history collections, is a similar growth, only its skeleton is composed of silica, which in appearance resembles colorless glass. For this reason the name “glass-sponge”’ is often applied to the framework of this group of animals. The animal tissues of this sponge, as of others, cover the interlacing fibers of the framework which acts as a supporting structure.

The skeleton itself is sometimes formed, as in this example, of needle-like structures, which are called sponge-spicules. In other sponges, these spicules may take the form of anchors; of hooks that may be single or double; of a long axle with a wheel-like body on one or both ends; of a long, tapering rod with a knob at one end roughened by projecting spikes, and various other graceful and beautiful shapes. In the Venus flower-basket these spicules are scattered throughout the sponge walls, and often are welded together or so interlaced as to form a very beautiful network. The specimen from which the accompanying illustrations were made, is about a foot in length; not quite all of one is shown in the illustration.