They occupy abandoned snail shells by thrusting the abdomen into the shell and holding onto it with the hooks on a pair of leglike organs. They do not kill the original owner of the shell, though they will fight other hermit crabs to determine occupancy of a shell. The hermit crab drags the shell behind as it walks about. As the crab grows larger, it seeks a larger shell. DIET Crabs inhabit a diversity of places and eat a variety of foods.
Most crabs feed on small fish or worms or else scavenge along the shore or sea bottom.
Most crabs, however, are scavengers, eating dead or decaying material. There is a commercial diet available for hermit crabs kept as pets, however hermit crabs seem partial to the roots of potted plants, and have been observed to dig up plants kept in their cages. The crab's reproductive organs are situated near and just below the heart and open to the outside at the base of the last pair of walking legs in the male, and at the base of the middle pair of walking legs in the female. In most species, the female carries the eggs cemented to her undersides and protected by the flexed tail. The fourth stage of development is the megalops.