Hermit crabs typically go about their molting business below ground away from your prying eyes and nosey tank mates but this isn’t always the case. Sometimes you will find yourself with a surface molter on your hands. Surface molts can be very cool for you but additionally stressful for the crab.
Let’s look at the best way to handle a surface molter.
First do not touch or move the crab! Unless you feel you must to ensure it’s safety.
Second find a way to securely isolate the crab from it’s tank mates.
It is extremely important that your tank temperature and humidity are in the proper ranges at this time.
Do not mist a soft hermit crab, there is danger of causing an infection by over wetting the soft exo.
Do not remove the shed exoskeleton (skin), your molter is going to eat that and it’s important that he does!
Do not place your molter in total darkness. Normal light cycles are needed!
If your hermit crab is surface molting in a PPDRM tank with other crabs you can create an isolation chamber for them by cutting the bottom off of a 2L plastic bottle and then placing it over the molter and pushing it down into the substrate, all the way to the bottom of your tank. Remove the lid.
If the bottle can’t reach the bottom, it is useless and other precautions should be taken.
If you simply can not securely isolate the surface molter, you may be forced to move them. You need to have some sort of container ready, preferably something that can stay in the same tank where the molt has occurred. Very small kritter keepers are ideal for this as they have secure lids but are vented for air flow.A disposable resealable bowl will work as an in tank isolation, poke holes in the lid. As gently as possible move the molter AND the shed exoskeleton to the isolation container. Do not poke, prod or otherwise futz with the molter. This will keep tank mates from cannibalizing the molter while it is soft and defenseless. Wash your hands before proceeding. A clean, plastic serving spoon can be used to gently scoop up the molter along with a bit of substrate by pushing the spoon into the substrate beneath the crab. This will prevent the hermit crab from being touched directly and allow you to safely transfer it to the isolation unit. No water or food is needed at this stage.
When your molter has fully hardened up and finished eating it’s shed exoskeleton, it is time to go back to the main tank. Monitor the molter and the tank mates for signs of aggression. Aggressive behavior is an indicator of a bigger problem, usually over crowding or inadequate diet. Many new hermit crab owners confuse mating behavior with aggression. Female hermit crabs are fertile and ready to mate after they finish molting and this is what causes the (male) tank mates to show such an intense interest in a freshly molted crab and not the ‘molting scent’.
Do not bathe your hermit crab before returning to the crabitat! This was once the recommendation but I believe now that it was based on a misinterpretation of natural behavior.
You can see mating behavior in hermit crabs on our Youtube channel.
I understand that it is very fascinating to be able to watch the molt process happening but remember your presence is threatening to the hermit crab at this time. If you want to take a photo, do NOT use the flash! Limit your photo taking and time spent hovering and try really hard to let your hermit crab do his molting business in peace and quiet.
Surface molting is often confused with death. Never assume a crab is dead just because it appears lifeless.
Read more: Is my hermit crab dead or molting?
Coenobita rugosus post surface molt munching on some delicious exo:
References:
Invertebrate Zoology, 7th ed. Robert D. Barnes, Edward E. Ruppert, Richard S. Fox
Biology of the land crabs Edited by Warren W. Burggren , Brian R. McMahon