Common shrimp (Crangon crangon) in a rock pool. Shrimps are marine crustaceans of the order Decapoda, which are mostly found on shallow sea floors where they feed on small animals and plants. They are related to crabs and lobsters. Shrimps have muscular abdomens and tail fans, which are used in conjunction to swim backwards away from predators. They are an important fishing resource, the edible part being the abdomen.