Sea Sponges

Although they may look plant-like, sea sponges are the simplest of multi-cellular animals. A sea sponge is a bottom-dwelling creature, which attaches itself to something solid in a place where itcan, hopefully, recieve enough food to grow. The scientific term for sea sponges is Porifera, which literally means "pore-bearing". A sea sponge is covered with tiny pores, called ostia, which lead internally to a system of canals and eventually out of one or more larger holes, called oscula. Within the canals of the sea sponge, chambers are lined with specialized cells called choanocytes, or collar cells. The collar cells have a sticky, funnel-shaped collar and a hair-like whip, called a flagellum. The collar cells have to purposes. They beat their flagella back and forth to push water through the sponge. The water brings nutrients, oxygen, and the collars pick up tiny bits of food in the water. Another type of cell, named an amebocyte, carries food throughout the sea sponge. Sponges are filter eaters and they can eat small particles of bacteria, or very large particles. The sea sponge is made of tiny needle-like splinters called spicules, a mesh of spongin. Many sea sponges can only be seen through microscopic examination, which makes taking photographs of them very difficult. Credits go to: Google