Structure and Function: Sponges belong to the phylum cnidaria. They have a simple organ system and radial symmetry. They have a simple nervous system called a nerve net. Sponges reproduce asexually by budding.
Ecology: The main role sponges play in an ecosystem is food. Though they sting fish and eat them themselves, sponges have a very primitive form of moving and have no sense of direction or even a brain. They are eaten by animals such as seals, seabirds, pink salmon, sun fish, turtles and other gelatinous creatures.