FIGURE 29.6
A sponge. Sessile animals without specilized organs and tissues, sponges filter food from water pumped through their porous bodies. A sponge must filter about 1 ton of water to grow 1 ounce. The diverse species of sponges vary in shape and color, some brightly pigmented by symbiotic algae. This is an azure vase sponge, Callyspongia plicifera.