Hermit crabs are often mistaken for being dead when molting their exoskeletons.
During the second phase of the molting process, hermit crabs appear lifeless. Aside from the tip of the tail, most of the body hangs limply outside the shell.
The exoskeleton is made of chitin, a type of protein. The molting process involves hermit crabs shedding their external exoskeleton (the hardened skin that protects the soft flesh beneath).
Is my hermit crab dead or molting? Well, it’s sensible to await clear signs of molting vs. death.
The hermit crab is likely dead if you smell a rotten or fishy stench. However, molting hermit crabs can also give off an unpleasant odor, so a decomposition-like smell is inconclusive.
Hermit Crab Molting Process
Hermit crabs shed their exoskeletons to grow and develop, regenerating lost and badly damaged limbs.
The exoskeleton comprises two layers: the outer protein layer is called the epicuticle, and the inner chitin-protein layer is called the procuticle.
There are four stages to the molting process:
Pre-Molt
The pre-molt happens before the molt occurs, indicating an impending molt.
Buds will form where limbs used to be in readiness for regeneration. Hermit crabs will begin to store water and food in their shells and may stop eating before molting.
Molt
This is the shortest stage, occurring when hermit crabs shed their exoskeleton. Hermit crabs become immobile during this time due to losing their muscle control.
Terrestrial or land hermit crabs remain in their shells during this stage to protect themselves.
Post-Molt
The new exoskeleton starts to harden, and the hermit crabs regain muscle control. At this point, hermit crabs eat their old exoskeleton to gain minerals (like calcium) and salts to aid calcification.
Intermolt
This is when the exoskeleton hardens. This is the period between molts, called the rest period. This stage takes longer as hermit crabs grow older, but molts become less frequent.
Signs Hermit Crabs Will Soon Molt
Here are the signs a hermit crab is about to molt soon:
Eating And Drinking More Than Usual
Hermit crabs contain a molt sac on their abdomen. This stores the water they’ll drink and helps break open the exoskeleton when molting commences.
A hermit crab about to molt will store food to sustain itself. If so, you may notice a dark-colored (black) fat bubble forming on the left of the abdomen beneath its fifth pair of legs.
Spilling Water
Humidity makes it easier for hermit crabs to shed their exoskeletons.
Consequently, you may observe lower water levels in bowls, damp substrate near water bowls, or see hermit crabs intentionally spilling their water.
Unusual Activity
If a hermit crab is usually active, you may observe a stark decrease in physical and antennae movement. A hermit crab may also start burrowing into the substrate or changing shells more frequently.
Appearance Changes
You may notice a change in the hermit crab’s color. Its body may be ashy or dull, and its claws and legs may change to a whitish color.
Their legs and claws may look droopy, and their eye stalks may turn away from each other and resemble the letter “V.” The eyes will develop a cloudy appearance.
Limb Regeneration
If a hermit crab is missing a limb, you may begin to see tiny buds appear where the limbs used to be in the days leading up to a molt. During the molting process, lost limbs will regrow.
What Does a Molting Hermit Crab Look Like?
Since the molting process has different stages, the hermit crab will look different depending on where it’s at in the molting process.
If it’s molting on the substrate surface, you’ll likely only be able to see what it looks like. Most hermit crabs bury themselves in the sand to molt.
Looks Dead
If you can see the hermit crab, you may notice that it looks motionless and limp, almost as if it’s dead.
Out of Shell
It’s normal for some hermit crabs to come part the way out of their shells during the molting process.
Normal Color
If you noticed pre-molt that a hermit crab’s color had become dull and ashy, you might see its color returned during molting.
How Long Does It Take for a Hermit Crab to Molt?
The time it takes for hermit crabs to molt varies based on the size and health of each hermit crab.
Molting can take from 2-3 weeks to about 2 months. Typically, the smaller the hermit crab, the less time it takes to molt. The larger the hermit crab, the longer it takes to molt.
How Often Do Hermit Crabs Molt?
Adult hermit crabs molt every 12 to 18 months, while younger ones do so more frequently. However, there isn’t a set number of times hermit crabs will molt during their lifespan.
Some factors, like shell size and a lack of alternatives, can make molting occur more often.
The New Zealand Journal of Marine and Freshwater Research stated that hermit crab shells that are too small or heavy restrict growth, leading to more frequent molts.
It goes on to state that when hermit crabs are limited in their choice of shells, they must choose whatever shell they can find. Sometimes, those shells are too small.
When they can’t find a larger shell, their growth becomes restricted by the smaller shell. Annual Reviews stated that captive hermit crabs may molt less frequently.
Add shells of different sizes to the hermit crab’s tank. Providing other choices ensures it never has to worry about size restrictions after a molt due to inadequate shell size.
Is My Hermit Crab Dead Or Molting?
Molting and dying hermit crabs share characteristics, making the distinction difficult for new owners.
A dead hermit crab will begin to decompose, generating a foul odor akin to rotting fish.
If you’re unsure if you have a molting or dead hermit crab, put it in an isolation tank. Just maintain appropriate tank conditions and provide food and water.
Avoid further disturbing the hermit crab because this will only cause further distress.
