Care for a molting Hermit crab

 Caring for your hermit crab through each molt is one of the most important things you will do as a hermit crab owner.  Molting is a natural process that every hermit crab must undergo many times during it's lifetime in order to grow. Molting doesn't require an owner's direct involvement, however, hermit crabs are extremely vulnerable during this time and can have adverse outcomes (i.e. limb loss or death) from a molt that is not optimal.  The important thing for you as the owner is to recognize when your crab is in this vulnerable period and be sure to provide the optimal environment and protection so they can molt safely on their own.




Signs of a Pre-Molt Hermit Crab


Learn to recognize the signs that your hermit crab is in the pre-molt phase. The importance of recognizing this is so that you can do things to ensure they are safe when they go down for molt. You want to provide the right conditions to ensure that they will not prolong their molt, to wait for better conditions; a molt prolonged for too long will be fatal.

Note: Not all crabs will exhibit such obvious behavior, some may go down for a molt without showing the signs below.

  • Increased Eating and Drinking - Your hermit crab may eat larger quantities of food and for longer periods than usual. They will spend more time drinking fresh water and salt water

  • Increased Bathing - Your hermit crab may bathe more frequently, climbing into the water dishes, or sitting on the edge of the dish and soaking.

  • Behavior Changes - Your hermit crab may seem like a different little creature, becoming less active,  more timid, hiding and sleeping more; they may even become crabby with fellow tank-mates or with owners. It is best not to handle them at this time as they are preparing for a serious process.

  • Moving Slowly and Awkwardly - Your hermit crab may seem like he/she's sick or injured. They may have difficulty walking, especially moving the big claw and often drag it and have a difficult time lifting it. They often have a low-to the-ground posture as if they can't hold themselves up. If they are lifted up, one limb often sticks out on its own. The antennae may move in a spastic jumbled appearing manner.

  • Physical Changes - Your hermit crab may develop a dull exoskeleton with white separation at the limb joints, pale limb tips, cloudy eyes and downward pointing eyestalks. These are usually late findings. There may be a dark bubble or storage pouch visible on the abdomen when they change shells; this contains extra fluid needed for the molt. 

  • Shell Shopping and Tank Climbing - Some hermit crabs will frantically try on multiple shells, to find the best fitting shell before going down. They may be more prone to shell fights as they become desperate to find the right shell. They may choose a smaller shell and change again after molting. They may also wander restlessly around the tank and place their claws on the sidewall as if trying to climb out while they scoot around the perimeter of the glass.

  • Digging - Your hermit crab may start digging holes in different locations in the tank, seeking the best spot to molt in. They may even burrow and re-surface before they actually settle down to molt.

How to Support a Pre-Molt Hermit Crab









How to Support a Molting Hermit Crab

When your hermit crab is underground molting you should leave him or her alone. They will burrow when they are ready, create a special molt cave based on their size (hence deeper sand is needed for larger crabs) and while wearing their shell, shed the exoskeleton underground, then eat it.  It's a complex process regulated by hormones and for a time period they are actually unable to move their muscles. They are extremely vulnerable, don't dig them up to check on them or take pictures and don't disturb the sand around them. If you are able to see them while molting, don't make loud noises, move abruptly, or flash bright lights around them as it will startle them and could disturb their molt. They need a stable, relatively dark environment to release the hormones for molting. As noted by the experts, the normal daily cycles of day and night should continue in the tank. Make sure the humidity and temperature of the tank will remain stable and in range without major fluctuations. As cold-blooded creatures, they will choose the spot in the tank with optimum temperature and humidity because they won't be able to move to regulate these elements. Don't change the location of the heating elements while the crabs are underground molting. If it becomes unsafe during the molt, they won't be able to move to regulate their body temperature or humidity as the other crabs in the tank can. If you happen to come upon their shed exoskeleton, don't throw it out or remove it, leave it for the molting crab to eat, unless it attracts other tank-mates. Check daily to ensure:

  • Temperature and humidity are correct and stable

  • Other hermit crabs in the tank are not digging in the area where the crabs are molting (If they are digging around the molting crab you may need to very carefully place a barrier).

  • There are no ant infestations or adverse tank conditions such as flooding which can harm the crab

Don't move the molting crab unless there are life-threatening conditions in the tank; moving a molting crab can cause it's death.

Note: If your crab  does not burrow and decides to surface molt it is a delicate scenario. You may have to provide more protective maneuvers, depending on your setup. It is best to seek advice from expert hermit crab keepers, forums, and owner societies for the best way to manage surface molting hermit crabs




When your hermit crab returns from molt

When your hermit crab surfaces from the molt weeks or months later, they may be weak, and usually very hungry. They may look different; be more pale, or darker or even change color or hue and have slightly different body markings. If they were missing limbs the limbs may have partially regrown. It is best not to pick them up as soon as they resurface because they will likely pinch you (hungry crabs pinch at anything), and also you could harm them if they are not fully hardened yet. They will often seclude themselves. Let them be for a day or few days. You may consider bathing them in order to wash off the molting smell - only if they are fully hardened and if their tank-mates start to bother them. It is important that there is food available so the resurfaced crab may may eat and regain their strength.  They may have to re-establish themselves with their tank-mates in the crabitat and may want to change shells if they have outgrown their previous one. They may still have shed exoskeleton left underground and may go back to finish eating. A newly molted crab cleaned up will often have a nice shiny exoskeleton, vibrant color, numerous fine hairs and sharp black claw tips.  Finally, you can rejoice that another successful molt has occurred and your hermit crab has surpassed the next milestone in your care!




Was this helpful? If so please feel free to browse the site and leave us a comment. To see cute hermit crabs in action, and watch their molting stories and more, check us out on Instagram and YouTube.


Posted October 9, 2017

The most important way to support your pre-molt crab is to allow them to prepare as they would in nature. Don't handle them or stress them out. If they are hiding or sleeping more, don't bother them. Make 100% certain they have the necessary tools to molt: 

Freshwater and Saltwater - This allows them the necessary pressure to split open the exoskeleton at the crucial point of the molt. If they don't have access to water, especially saltwater before the molt, they may not be able to successfully molt and could die during the process.

Nutrition Support - Hermit crabs should always have a diverse diet in general, this will help give them all of the nutrients they need to survive. However, extra nutrition support before the molt may be protective. Extra calcium (oyster shell, cuttlebone, egg shells, spirulina), helps to harden the new exoskeleton after the old one is shed. Extra natural oils (coconut oil, sesame oil, nuts and seeds) may help with loosening the exoskeleton and helping them to slip out. Extra protein (shrimp, worms, fish, egg yolk) may help with the building of the necessary elements, hormones etc. to direct the molt. Give these in addition to the usual diet and include carbohydrates and fruits.

Deep Proper Substrate - Natural playsand or  playsand and eco-earth mixture  (5:1 ratio)  only , 6" or deeper for larger crabs will be needed. These substrates will protect them from their tank-mates and allow them to be able to construct the proper cave to molt in. Don't use other substrates for molting crabs. The wrong substrate may cave-in  or trap them underground, or allow them to be attacked by fellow crabs. If the tank they share with other crabs does not have the proper substrate or depth, they should be isolated  to molt alone in a tank which has the proper substrate. Some owners believe eco-earth alone may not provide the best environment for molting.  Although crabs are able to molt successfully in this, some owners have reported higher incidences of adverse events.


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Brooklyn, NY, USA