They all eat plankton that falls from the surface. They also eat parts of other ocean animals. The starfish uses its long arms to pry open clams and scallops. The sea anemone sits on the ocean bottom waiting for a fish to fall prey to its poisonous arms. It looks more like a plant than an animal.
Most fish live in the deep water, just below the ocean surface.
Fish eat other fish to stay alive. Large fish eat smaller ones, which eat smaller ones, which eat still smaller ones. This eating pattern is called a food chain. This chain concept also resembles a pyramid. Each type of organism feeds on the organisms below it on the pyramid.