Freshwater hermit crabs are one of the rarest species of living beings found on earth. Before starting a discussion about the freshwater crabs, it is important to mention that these crabs are found only in one single lake all over the world, and they are rarest of the rare exotic animals.
There are several species of marine hermit crabs, and all but one species are inhabitants of alkaline water. The alkaline water crabs are natives of different oceanic regions around the world and they retain this nativity throughout their captivity even. That means that the salinity and the color of their captive waters must be like that in their native waters. However, although many marine species of these crabs have adapted to a captive environment in the company of humans, it is impossible to have the freshwater crabs as pets. Being a rarest species, any kind of human intrusion on their habitat is prohibited by international laws devised by the guardians of wildlife conservation.
The only freshwater reserve where these rarest inhabitants of earth are found to live is the coaster freshwater pool of Espirito Santo, Vanuatu of southwestern tropical Pacific. This coastal lake is located near the village of Matevulu and is adjacent to an abandoned airstrip. The hermit crab species that lives in this coastal lake are the Clibanarius fonticola of the genus Clibanarius. Zoologists McLaughlin and Murray first reported this sole habitat of the freshwater hermit crabs in 1990. The freshwater crabs are very unique and they only prefer the abandoned snail shells of the snail species Clithon corona. The Clithon corona shells are found in their natural lake. The natural lake of Espirito Santo is fed with freshwater from the nearby springs.
The reason of only a sole habitat of the freshwater hermit crabs can be traced back to the unique confluence of conditions of their magical lake habitat. Being always fed by running streams, this freshwater lake has a condition of running water that is so essential for the marine crabs for breeding. In addition, since the lake is located in a coastal region, there must be underlying elements of alkalinity in the lake water that makes this habitat so favorable for the crabs. This confluence of running water and underlying alkalinity makes the pool the only ideal location for the survival of the Clibanarius fonticola species. The distant and private location of the lake is also a main reason why these crabs have chosen the lake as their only freshwater home.
Some of the other members of the Clibanarius genus like the Clibanarius erythropus, Clibanarius signatus, Clibanarius tricolor, Clibanarius snelliusi and Clibanarius englaucus can live in marine aqauariums if their native conditions are adequately provided in their captivity. The genus Clibanarius, under the family Diogenidae, also have a very special identifying character. Unlike all the other crabs, these crabs have their left claw enlarged and decorated and so they are also known as the left-handed hermit crabs.
Although other marine hermit crabs do not have any freshwater requirement, yet surprisingly, the land crabs only drink freshwater for their survival. In this respect, perhaps it will not be irrelevant to christen these land crabs as freshwater hermit crabs. These land crabs drink freshwater for their nutritional needs, but they prefer to bath in an alkaline water container.