the skeleton of the sponge is composed of tiny needle like splinters called
The skeleton of the sponge is composed of tiny needle-like splinters called spicules, a mesh of protein called spongin, or a combination of both. Many sponges can only be identified by microscopic examination of the skeleton, which makes certain identification from photographs difficult.he collar cells have a sticky, funnel shaped collar and a hairlike whip, called a flagellum. The collar cells serve two purposes. First, they beat their flagella back and forth to force water through the sponge. The water brings in nutrients and oxygen, while it carries out waste and carbon dioxide.