Hermit crabs are a group of crustacean, which all have in common that they use shells of snails to cover their abdomen which is softer then the one of other crabs. There are about 500 different species of hermit crabs all over the world, most of them aquatic, but also a few terrestial. Species include the Common Hermit Crab (Eupagurus bernhardus) on most European coasts.