Land hermit crabs prefer to stay on the sand for the most part, heading for water periodically to take a drink or a quick dip. Land hermit crabs are designed to live outside the water except for reproduction, their bodies require hydration inside and out. Keep the right kind of water available for your pet.
Hermit crabs usually have a large claw and a smaller claw, both of which are capable of scooping up water for the crab to drink. A hermit crab can drink sitting in a pool of water or sitting alongside, reaching in with a claw and scooping up water. He usually scoops water into his mouth, although you might see him bring water toward his gills occasionally.
Types of Water
Two pools of water keep pet hermit crabs hydrated and happy. One pool should be freshwater and the other should be saltwater. Although your crab normally drinks freshwater, don't worry if he takes a gulp or two of saltwater; he won't overdose on the salty stuff. Use shallow plastic dishes that are easy for the crab to climb into without tipping them over. Place pea gravel, small river rocks or pieces of natural sponge in the bottom of the dishes to help the crabs move around inside them and to give them a variety of depths to choose from.
Keep It Safe
For both pools of water, use bottled or distilled water, or treat tap water with dechlorinator -- the chlorine can kill hermit crabs if they drinks it. Keep the water levels deep enough that your crabs can submerge part of his body and shell, but not so deep that they can submerge completely and drown. When adding salt to the water for one of the pools, use only ocean salt, not table salt. The iodine in most table salt can hurt your hermit crab. Change the water daily to remove dirt and debris.
In addition to drinking water to stay hydrated, hermit crabs need to keep their gills and bodies moist. They do this in part by keeping a small amount of water in their shells. When your crab is sitting in a water dish -- either saltwater or freshwater -- he might be replenishing his shell water, which is as essential to his survival as drinking the water.