How Can I Tell When My Hermit Crab Is Getting Ready to Molt?

Signs of Molting

Close-Up Of Hermit Crab
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Your hermit crab will likely start to act and look a bit different just before molting. Be prepared for molting as some hermit crabs may surprise you when you least expect it. Keep a close eye out for the signs below so you can support your molting hermit crab through this stressful time. Once these signs manifest, consider isolating the hermit crab from the other crabs.

The entire molting consists of several stages: preparing for the molt; shedding of the exoskelton;  hardening of the exoskeleton; and a recovery period. The  shedding doesn't take very long, but the stages that proceed and follow the shedding often some time to complete. A crab will bury itself when molting begins and it's best to leave a hermit crab alone and let nature take its course. Check on him occasionally by looking at him but don't pick him as you can cause damage.

Signs your Hermit Crab is Getting Ready to Molt

  • Digging more than usual: A healthy crab that is suddenly digging is a sign that molting is approaching. However, first check your thermometer and humidity gauge. If a tank is too warm, cold or dry, your crab cold be trying to dig a new habitat underneath the sand to get away from unwelcome conditions.  
  • Eating and drinking more than usual for a bit before the molt. Molting hermit crabs first store up a lot of fat and water and gorge like crazy! However, all of this overeating usually takes place at night when you're asleep so you likely won't see it. A crab will usually store his extra fat and water in a small black "bubble" on the left side of the stomach under its fifth pair of legs, though this is not always the case. This molt sac stores water to help break the exoskeleton when it molts. In the last few days before starting a molt, your crab may stop eating.
  • Lethargy and decreased levels of activity, though may seem restless (repeatedly digging, changing shells)
  • Tangled-looking antennae and less antennae activity.
  • Ashy colored body. Tips of legs and claws may turn whitish.
  • Spending more time around water.
  • Crabs that are missing limbs start to regenerate their limbs by starting to grow a "gel limb" (a gelatinous bud that eventually grows into a regenerated limb) just before a molt. The missing limb will look like it's growing a small, clear, gel-like nub which is actually the limb surrounded by a clear chitin sheath. As time molting approaches, the crab's gel limb will expand and become more defined
  • Legs and claws may seem droopy or weak.
  • Eye stalks may face away from each other in a "V" shape rather than being parallel. They may also appear cloudy, whitish and dull, like a human's cataract.

Go to Hermit Crab Molting FAQ for more on molting hermit crabs.