The importance of Water.

It used to be thought that land hermit crabs could live "happily" with a very small amount of water , even at one point it was thought that salt water was not necessary.

However, as more was learned about these creatures and their requirements, it became clear that all hermit crabs actually require salt water in order to live a healthy life. Land hermit crabs are unique because they are only partially land animals, they carry a water source around inside their shells and require a tropical environment in order for them to function properly, namely the gills, which can dry out and the crab can die from suffocation and dehydration. Land hermit crabs are really only partially land animals because, they do not breath only air or only water but rather a combination of both, this is why their gills must remain moist. However, a steamy and hot environment is also a very bad idea, that sort of setup can lead to big problems as well.

Land hermit crabs use both fresh and sea water to balance their specific salt content in their body , they will mix fresh and salt water in precise quantities which they store in there shells. Sometimes this will spill out when they are being handled. All species of hermit crabs spawn their eggs in the ocean as well.

Until fairly recently it was recommended that hermit crabs should only have shallow water dishes because it was thought that they would drown if they where completely submerged underwater for any longer period of time.

However, that mind set in the hobby is changing. In reality hermit crabs can stay under water for a surprising amount of time. Not only can they do this, but some species seem to do this willingly, such as perlatus and violacens. The length of submergence seems to vary slightly from species to species and even individual to individual. Some species-namely clypeatus- only stay under very briefly if ever, while violacens and perlatus will linger in the pool area for hours, one crab of mine even stayed under water for a enormous four hours!

Strawberry hermit crabs have been thought to require deep saltwater pools for a while. This idea come from the fact that they seemed to spend an excessive amount of time in and around the salt water dishes. However, even when deeper water dishes were added that did not seem do anything significant to alter their survival rate in captivityl. I personally think that C.perlatus (Strawberries) have a higher sensitivity to 'water quality' then the other species of land hermit crabs, particularly to the specific gravity of salt water. Strawberries seem to lack some of the salt retention qualities of their counterparts.

You can measure the specific gravity in your water by purchasing a ' Hydrometer'. I recommend the small 'box' type, while regarded from some as toy like, it works fine for my purposes.

The reading you should be aiming for is 1.020 to 1.026, the hydrometer makes this easy by highlighting the ideal ranges in red. Slightly lower or higher does not seem to make a huge difference to the crabs because they should be able to balance out the extra with fresh water, generally higher rather then lower is better however.


I personally think the best way to provide water for hermit crabs in captivity is large pools of both fresh and salt built into the tank. While this may not work for everyone, I highly recommend them to the serious hobbyist.

Cheers.

S.P

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