Hermit Crabs – Molting

Imagine what it would be like if every time you grew an inch, your skin got so tight that you had to shed it! Our human skin grows with us; however, hermit crabs (a popular exotic pet in recent years) do not have this same luxury. Their outer skin does not grow with them, so when it gets too tight they must shed it in a process that is referred to as molting.

What is an Exoskeleton?

The exoskeleton is just another name for the outer ‘skin’ of the hermit crab that does not grow with them. It is hard and inflexible because it acts like a protective shield. It is a barrier and multifunctional unit with many other functions including prevention against drying out (it keeps in moisture). Essentially, it is like our skeleton covering the outside of the hermit crab’s body. It serves the necessary functions to ensure the survival of the species. However, one of the potential downfalls is its inability to grow with the body, and hence it must be shed when the crab outgrows its body.

How Can I Tell if My Hermit Crab is Going to Molt?

Unfortunately, some hermit crabs may begin a molt with no prior signs, or the owner may not pick up on them. Although the hermit crab molt may proceed just fine, when signs are noted, the hermit crab should be placed in a location away from other hermit crabs. This is because hermit crabs tend to practice cannibalism (eat their own kind) on molting hermit crabs! Along with being isolated, their environment should be kept undisturbed and moist. So back to these signs – what are they?

1. Digging: though digging is a perfectly normal behaviour for hermit crabs, an increase in digging can signal the onset of a molt.
2. Increased eating/drinking: the reason for this is to store energy that they can use during the molt – much like squirrels storing nuts to eat during the winter. Hermit crabs actually store this food and water in a little black coloured bulge on their abdomen, which can be spread out on the body of the crab and quite difficult to see.
3. Growth of extra limbs: This applies to crabs that have lost limbs. Similar to how starfish grow back their ‘arms’ when one is cut off, hermit crabs (when they are nearing a molt), will begin to grow back what looks like a limb made out of jelly.

Molting is an Energy Expensive Process

Take a minute to ponder how difficult this process must be for your hermit crab. Getting rid of its entire outer layer requires a huge amount of energy for such a small creature, thus this is a very stressful time for your crab. Before and after your crab has molted it will probably dig in the sand, burying itself to conserve energy and remain moist in preparation for the big molt. If it has unsuitably prepared itself, there is the possibility that it may not survive this essential process.

What Can I Do to Help My Molting Hermit Crab?

Do nothing. This is by far the most beneficial thing you can do for your pet. Far too many people mean well, but it can be quite easy to kill a molting hermit crab with kindness. Ensure that its habitat is kept moist, and there are no other hermit crabs around (the cannibalism issue). Your hermit crab knows what it is doing so be patient. Molting times will vary widely among hermit crabs and could even take a couple months. When your hermit crab has ‘woken up’ from its molting, it will look pinker and be softer. It needs time to harden its exoskeleton and is still very vulnerable at this time.

What Do I Do with the Molted Skin?

The exoskeleton that your crab molted should stay in the container with your crab. It is a very energy-dense source of nutrients that will help to nourish your crab and help it on its way to forming a new exoskeleton that fits its body.
To summarize, hermit crabs change their ‘skin’ like we change shoes. When we grow up, our feet grow too big for our shoes and then we get uncomfortable and our toes pinch against the tips of our shoes. This is what occurs with hermit crabs, as they have an outer exoskeleton that does not grow with their body. In a process that requires a lot of energy, they shed this old exoskeleton and grow a new one that ‘fits’ better. During this time, a hermit crab should be left alone as much as possible. This process takes a lot out of them, but if everything occurs with no complications, they will emerge a whole new crab.

By Laura Platt – Pets.ca writer