Many sea creatures do not go hunting for food. They simply open their mouths—if they have mouths—and suck in the sea water. From it they strain out the food particles as they go by. In open water these particles are plankton. On the bottom there is a kind of slime composed of decaying matter and the bacteria that break it down. as well as swarms of tiny living things.
Sponges and sea squirts anchor themselves to rocks or other solid objects and feed by pumping water in and out of their openings. Oysters and clams are pumpers too, and the oysters spend their whole adult lives quietly in beds.
Some organisms make a little more effort. Barnacles catch food bits in the bristles of their outstretched hairy legs. Sea cucumbers snuffle along the sea floor like vacuum cleaners, shoveling slime into their mouths with tentacles. They may cover 18 inches a day.
The sea anemone looks like a flower but actually is a meat-eating animal. By means of a slimy disk on its underside, it clings to rocks or glides along the bottom. It catches small fish in its stinging tentacles, then draws the paralyzed prey into its mouth.
One large free swimmer which comes down to the bottom to feed is the eagle ray, which uses its wide, winglike fins to stir up the sand in search of mollusks. As it digs it scoops up the clams and crushes them between its rows of flat teeth
