Hermit Crab Surface Molt

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.

Coenobita clypeatus - Purple Pincer Hermit Crab Surface Molt — Coenobita clypeatus – Purple Pincer Hermit Crab Surface Molt

C. compressus surface molt. Top most leg is a newly regenerated limb. — C. compressus surface molt. Top most leg is a newly regenerated limb Photo by Nichole Edwards.

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.
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!

ISO bottle should be pushed all the way to the bottom of your substrate so there is no way for another crab to burrow in from below.

In place isolation of a surface molter can be accomplished by cutting the bottom off of a 2L plastic bottle and then placing it over the molter and pushing it down (gently!) into the substrate, all the way to the bottom of your tank. Remove the lid. If you have molters down, do not do this. If the bottle can’t reach the bottom, it is useless and other precautions should be taken.

Kritter Keeper used in main tank as an ISO for surface molters

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 it’s 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. 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.

Jonathon Livingston Crab hardening after a molt.