Blood Sponge (Echinodictyum)

Sponges have the simplest structure of all multi-celld marine animals. The body consists of a fibrous matrix, sandwiched between two layers of cells. The animal is riddled with numerous holes leading into a series of canals, partly lined with special cells that have projecting hairs. The vigorous movement of these hairs creates a current, moving food-laden water through the sponge. The current creates a vacuum effect, drawing the surrounding water into the outer pores. The water, along with the sponge's waste products, is eventually expelled through large conspicuous opening. A typical sponge pumps water equal to at least four to five times its own volume per minute. For a football-sized sponge this translates into a quantity of several thousand liters every day. The Blood Sponge is usually found on outer reef slopes, exposed to strong currents, at 10-40 m (30-130 ft) where it appears to be dark greenish-brown. However it is bright red if illuminated or brought to the surface.