Blue-spotted Hermit Crab (Dardanus guttatus)

The Hermit Crab's practice of using a dead using a dead mollusc shell as a portable home is well known. They are often seen lugging their cumbersome shells in broad daylight, unlike most crabs, which avoid daytime fish predators by being active only at night. Furthermore, they are not vulnerable when shedding their hard outer covering (moulting), a typical crab trait during periods of growth. The Hermit Crab simply finds a larger shell and moves into its new quarters. If you attempt to dislodge a hermit crab form its shell, you will find it an impossible task, without physically damaging the animal. After moving into a new shall, the crab's flexible abdomen adopts a twisted shape that perfectly follows the bend of the shell. It can constrict or expand the abdominal muscles so that the body presses tightly against the shell and fills every empty space. Most common Hermit Crabs belong to the family Diogenidae. They occur from the shallow intertidal zone down to depths of at least 100 m (330 ft).