According to the adaptation of habitat, hermit crabs can be classified as marine hermit crabs and land hermit crabs. Although the members of all species of hermit crabs need a running water environment for breeding and hatching their eggs, yet the physiology of land hermit crabs do not allow them to survive in a marine environment. In the same manner, the marine hermit crabs find it impossible to survive above water. The marine crabs breathe through gills using the oxygen dissolved in water. The land crabs have a modified gill mechanism that absorbs oxygen from the humidity in the air.
The marine species of the hermit crabs are always coastal dwellers in their native habitats. Among the diversity of marine hermit crab species only a few of the marine crabs have agreed to stay in captivity. Clibanarius tricolor, Clibanarius digueti, Paguristes cadenati, Calcius elegans and Pagurus bernhardus are the species of marine hermit crabs that can survive in a suitable aquarium setting. The tricolor hermit crabs are also known as blue-legged reef hermits and the digueti crabs are known as the red legged reef hermits. The crabs of the cadenati species are also reddish in color, and they are known as scarlet hermit crabs. The good name of the elegans hermit crabs is electric blue hermit crabs.
An essential prerequisite of maintaining a crustacean pet is the construction of a good saltwater aquarium, or more correctly a saltwater marine reef system at home. The salinity of the saltwater, the aquarium temperature and the aquarium installation all are to be determined according to the specifications of the hermit crab species you are keeping at the aquarium. This is because, all the marine hermit crabs are natives of different oceans around the world and the alkalinity of every ocean water is different. The aquarium should be free of ammonia, nitrites, nitrates and chlorides. The rock installations inside the aquarium should have enough jaggedness for the hermit crabs to take rest when it intends. Select rocks with crevices and cracks to let the hermit crabs give more option of resting spaces. The presence of jagged rockfaces is also essential to give the hermit crabs sufficient climbing space. Hermit crabs like to climb and while they climb, the reincarted snail shells on their backs climb with them.
A general estimation of safe salinity in water should be at 30-40 ppt and the specific gravity of the water should be maintained at a general range of 1.022-1.0240. You will need aquarium instruments like a saltwater test kit, a hydrometer and a thermometer to maintain a stable nitrogen cycle inside the aquarium. To know more about nitrogen cycle in saltwater aquarium see http://www.hermhtcrabhappy.moonfruit.com/#/nitrogen-cycle/3006618252 .
Since hermit crabs are omnivorous scavengers, they will eat anything that will taste good to them. Their common foods include green algae, shed exoskeleton, fish leftovers and organic wastes found inside the aquarium. In addition, it is important to maintain cleanliness of the reef aquarium for the comfortable living of the hermit crabs. The larger sized members of the aquarium are more voracious eaters than the smaller members of the aquarium.
A great difference between the land and the marine hermit crabs is in their molting patterns. The marine crabs do not show any prior symptoms of molting like their male counterparts. They might become slightly lethargic but that is all. Most amazingly, the molting process of marine crabs gets completed in one or two minutes which is a great contrast to the land neighbors who take up to a month to molt. Another interesting point is marine hermit crabs do not prefer to eat their own exoskeleton, although they favor to eat the exoskeleton shed by other members of the aquarium.