Caption:
coelenterates are aquatic, mostly marine. The body form is radially symmetrical with a tissue grade of organization. The body has a single opening hypostome surrounded by sensory tentacles leading into a spacious cavity called the gastrovascular cavity or coelenteron. Digestion is both intracellular and extracellular. Respiration and excretion are accomplished by simple diffusion. A network of nerves is spread throughout the body. Many forms exhibit polymorphism, wherein different types of individuals are present in a colony for different functions. These individuals are called Zooids. These animals generally reproduce asexually by budding, though sexual reproduction does occur in some groups.