Starfish are powerful hunters and primarily feed on mollusks. Their main sources of food are clams, oysters sand dollars and mussels, which are usually attached to rocks or otherwise unable to escape quickly. They also eat snails and injured fish, when they can find them. Not all starfish hunt for meat, however. Some species find decomposing plants and animals in the water or on the beach and consume them, making for much easier prey but lower nutritional value and increased competition from birds. Other starfish hunt in the water, catching sponges, plankton and even coral for their dinner.