Molting is the natural process of growing for a hermit crab. During this time, it sheds its exoskeleton and forms a new one. During the molting process, a hermit crab is very defenseless. A molting crab is under a lot of stress and extra care is required during this vulnerable time. The frequency of molting depends on the size and growth rate of each individual crab. Smaller crabs, that grow much faster may molt every 3-4 months. Larger crabs that grow much more slowly may only molt once per year.
The first thing to remember is that when molting, a crab will bury him or herself; do not move him or her! As hard as it is not to pick him up and look to see if he’s ok, you must be brave and let him do his thing. Molting may take anywhere from 4 to 8 weeks for the average sized crab. Smaller crabs may take a shorter time; larger crabs may take longer. They may stay buried the entire time. Another important thing to remember is that molting crabs are in danger from other crabs while they are molting. Other crabs may attack the molting crab while it is vulnerable. Always keep the molting crab in an isolation tank. Most pet stores have dividers available to section off one part of an aquarium from another.
Once the process is complete, the crab should not just be put back into the main tank, as it takes awhile for the new exoskeleton to harden. The real way to tell if the crab is ready to be back in with the other crabs you may own is when they are active and appear healthy again. This process can take anywhere from a few days to a couple of weeks. Be patient and let your friend heal.
A question you may have about molting is how you will know when your crab is going to molt. There are usually pretty obvious signs. Your hermit crab will most likely start to act a bit differently and look a bit different just before molting. However, though there are crabs who exhibit obvious signs, always be prepared for molting as some hermit crabs may surprise you by molting when you least expect it. Keep a close eye out for the following signs and be prepared to support your molting hermit crab through this stressful and vulnerable time. Once you see these signs, you should consider isolating the hermit crab from the other crabs right away.
- Sluggishness or relative inactivity.
- Ashy body color.
- A crab might dig more than usual. (Always check tank conditions as this can also be a sign of temperature and humidity problems.)
- Eating and drinking significantly more. The crab may stop eating completely just before a molt.
- Spends lots of time around water.
- A molt sac, or water sac under the abdomen, may form.
- Missing limbs may occur.
- Whitish color on legs and claws.
- Cloudy, whitish color to the eyes Legs may seem weak.
- Eye stalks may face away from each other.
Observe carefully for these signs of molting and offer your hermit crab support. Remember, isolate him, and leave him alone. These are the best things you can do for your crabby.