Plankton, meiobenthos and humus. According to the query culture network, pregnant crabs mainly feed on plankton, meiobenthos and humus. These foods are rich in protein, carbohydrates, fat and other nutrients, which can meet the growth and development needs of pregnant crabs. Crabs are omnivorous crustaceans, with hard shells distributed all over the body, symmetrical bodies, different back shells with dark colors, a pair of claws and four pairs of walking feet.