<P> While most of the approximately 5,000--10,000 known species feed on bacteria and other food particles in the water, some host photosynthesizing micro-organisms as endosymbionts and these alliances often produce more food and oxygen than they consume . A few species of sponge that live in food - poor environments have become carnivores that prey mainly on small crustaceans . </P> <Ul> <Li> <P> Sponge biodiversity . There are four sponge species in this photo . </P> </Li> <Li> <P> Branching vase sponge </P> </Li> <Li> <P> Venus' flower basket at a depth of 2572 meters </P> </Li> <Li> <P> Barrel sponge </P> </Li> <Li> <P> Stove - pipe sponge </P> </Li> </Ul> <Li> <P> Sponge biodiversity . There are four sponge species in this photo . </P> </Li> <P> Sponge biodiversity . There are four sponge species in this photo . </P>

Where does most life in the sea occur