Land Crabs live on land and Marine crabs live in water.
Land crabs (most pets are) do need it while marine crabs like the ones you find at the beach do not.
You can tell a land hermit crab from a water hermit crab by looking at the claws/arms or legs. If it is a water crab it will be blueish and if land crab it will be pinkish purpleish. If your crab is a water crab don't just throw it in water and leave it there, put a tiny bowl in it's tank or cage that is low to the ground and make sure that the water level is a bit lower than the hermit crabs top of its legs. Also have a wet sponge for each kind of hermit crab in the crabs tank.
I'm not sure what you mean by this question. Hermit Crab is a term used to refer to many different species of crabs that live in shells that have been cast off by snails. They can be marine hermit crabs, or land hermit crabs. Within these categories there are many different species. The Genus Coenobita contains 16 different species of terrestrial (land) hermit crabs. The Genus Paguras refers to those species of marine hermit crabs.
Crabs are usually marine creatures, they occure mainly in oceans although some have become terrestrial (land crabs) whis then live in reasonable proximity to oceans.
Marine hermit crabs live underwater and can sometimes be found in tidepools. Land hermit crabs do not live in the water but need fresh and salt water to survive.
Penguins, seabirds, seals, Marine Iguana, some crabs, mud skippers.
Virginia = stable crops and land ; Massachusetts= marine trade and commerce
For land hermit crabs: Tropical or sub-tropical beaches/jungles. For marine hermit crabs: Oceas, seas, tidepools, beaches of all latitudes.
Marine iguanas, uniquely among all lizards, can forage in the sea, feeding on salt-saturated seaweed and exuding salt via tears.
The kind of hermit crabs most people think of are Land Hermit Crabs. They live on land, and need at least enough water to submerge themselves. Land Hermit Crabs do need sea salt to keep their body chemistry balanced, and as such, need access to both salt and fresh water. Marine Hermit Crabs require a full saltwater aquarium to survive. Such tanks are elaborate, and should be researched thoroughly before purchase. Saltwater pets of all sorts are often regarded as difficult to care for.
There are several species of Land Hermit Crabs and hundreds of species of Marine Hermit Crabs. As requested, here are 5 species of Land Hermit Crabs. Coenobita Clypeatus (Purple Pincher) coenobita Compressus (Ecuadorian) Coenobita Rugosus (Rug) Coenobita Perlatus (Stawberry) Coenobita Violensus (Viola) Coenotiba Bervimanus (Indo) - a bonus one!
Marine crabs breathe underwater using gills, which are located in a two cavities under the carapace. True land crabs have enlarged, modified cavities that act like lungs so that the land crabs can breathe air