<P> The main food sources for the benthos are algae and organic runoff from land . The depth of water, temperature and salinity, and type of local substrate all affect what benthos is present . In coastal waters and other places where light reaches the bottom, benthic photosynthesizing diatoms can proliferate . Filter feeders, such as sponges and bivalves, dominate hard, sandy bottoms . Deposit feeders, such as polychaetes, populate softer bottoms . Fish, such as dragonets, as well as sea stars, snails, cephalopods, and crustaceans are important predators and scavengers . </P> <P> Benthic organisms, such as sea stars, oysters, clams, sea cucumbers, brittle stars and sea anemones, play an important role as a food source for fish, such as the California sheephead, and humans . </P> <Table> <Tr> <Td> Macrobenthos comprises the larger, more visible, benthic organisms that are greater than 1 mm in size . Some examples are polychaete worms, bivalves, echinoderms, sea anemones, corals, sponges, sea squirts, turbellarians and larger crustaceans such as crabs, lobsters and cumaceans . </Td> </Tr> </Table> <Tr> <Td> Macrobenthos comprises the larger, more visible, benthic organisms that are greater than 1 mm in size . Some examples are polychaete worms, bivalves, echinoderms, sea anemones, corals, sponges, sea squirts, turbellarians and larger crustaceans such as crabs, lobsters and cumaceans . </Td> </Tr>

Is a sponge a plankton nekton or benthos
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