Depending on the species, sea crabs eat plankton, worms, fish, shrimp and other crabs. Crabs that live in the deep sea survive on foodfalls, which are scraps of meat that fall to the ocean floor after being killed by another sea animal.
Some crabs are born with a stored yolk that contains enough food for their first stage of growth. Others begin eating small plankton-like organisms right away. The Red King crab goes through a developmental stage where it is unable to eat or digest food.
Sea crabs can survive a length of time without food. This assists them when food sources are scarce or when they are looking for a new feeding area. .