Molting is a critical part of the hermit crab life cycle. As hermit crabs grow, they shed their exoskeleton and grow a new, tougher one.
Unfortunately, molting crabs are often mistakenly believed to be dead.
Molting hermit crabs remain submerged under their substrate and largely inactive for months, which can be confused with death.
Check regularly for a foul, fishy smell and signs of other hermit crabs attempting to eat a deceased friend. Shedding multiple limbs at once and going limp in the shell are other signs of death in hermit crabs.
You’ll need to be patient with molting hermit crabs, as disturbing them to check on their health does more harm than good. Only assume your pet is dead if other explanations have been exhausted.
My Hermit Crab is Not Moving
It is always worrying when hermit crabs stop moving. These animals are typically lively, active pets. If hermit crabs become completely stationary, something is usually wrong.
This does not mean that your hermit crab has died, though. Hermit crabs stop moving for many reasons. It may simply be sleeping, or destressing. Equally likely is that the hermit crab is molting.
When these animals outgrow their exoskeleton, they need to shed it and grow a replacement. This process takes weeks or even months. As molting hermit crabs rarely move and stay buried under the substrate, it’s understandable that you’re fearful that they have died.
Always leave stationery hermit crabs alone for as long as you can. There is every chance it is molting, sleeping, or hiding. There are signs that hermit crabs have died, but even these can be confused with molting.
Is My Hermit Crab Dead or Sleeping?
If your hermit crab is not moving during the day, this is normal. Hermit crabs are nocturnal and come to life after dark. Wait for the sun to set then provide food and you will likely see your hermit crabs spring into life.
Most hermit crabs sleep burrowed under their substrate. This is not always the case, though. Some hermit crabs like to sleep hanging upside down from the roof of a tank like bats. Hermit crabs also assume this position at night.
This stems from the exhaustion of climbing. Hermit cars love to climb. It’s an instinctive behavior carried over from their life in the wild. Climbing is exhausting for hermit crabs. Clambering to the top of a tank is fun, but they’ll likely need a nap afterward.
Naturally, a dead hermit crab will not be able to hold onto the roof of a tank. It would plummet to the ground. If it were not dead before, the impact and shock of such a fall may end life. If hermit crabs are holding on, you can relax as they are just dozing.
Is My Hermit Crab Dead or Hiding?
Your hermit crabs may also be hiding. Moving to a new location, especially in captivity, is stressful for hermit crabs. Everything they know has changed. It is not uncommon for hermit crabs to spend their first few weeks or months in captivity burrowed under the substrate.
Other factors may also be provoking stress in your hermit crabs. Ensure that tank humidity is at 80% and the temperature is around 80 degrees Fahrenheit. Adjusting these settings to appropriate levels will boost the comfort and confidence of hermit crabs.
Some hermit crabs also feel bullied and harassed by tankmates. Hermit crabs are social and enjoy living in groups. These animals can enter conflict over coveted shells, though. Hermit crabs that prefer to avoid going to battle will remain static in their shells or burrow to hide.
Is My Hermit Crab Dead or Molting?
The main concern for owners is confusing hermit crab molting with death. In some respects, molting is comparable to demise. It will completely shed its exoskeleton and grow a new one. This is almost a complete rebirth. Here are the signs that a hermit crab is about to molt:
- Eating more, leading to a ‘fat bubble’ on the abdomen
- Drinking and bathing more to store water in the shell
- Digging in multiple locations, as though testing ground
- Growing less active, moving to eat but playing and exercising less
- Skin tone fading to a dull gray or white
Most hermit crabs will burrow under their substrate to molt. This is so they can complete the process with safety and privacy. A molting hermit crab is completely unprotected. Consider moving it to a private enclosure if you think a molt is impending.
You must leave the hermit crab to molt in peace. Even if you suspect that it has died, leave it be. It could be three months before you are certain. If you try to dig up a molting hermit crab, the shock may kill it anyway.
Find out where your hermit crab has buried itself. Smooth over the sand in this position. If you find it a little raked and messed in the morning, it is active underneath. It emerged for a snack or drink.
How to Tell if Your Hermit Crab is Dead
If cared for appropriately, these hermit crabs can live for over a decade. The oldest captive hermit crab on record lived to over 40.
“If cared for appropriately” is a big caveat here. Hermit crabs are very delicate. There are many reasons why hermit crabs die suddenly, seemingly without explanation. Do all you can to minimize this risk.
If you have a dead hermit crab in your enclosure, it must be removed. Whatever killed it may infect other tankmates. Before you take such steps, ensure that the hermit crab is dead by checking these signs:
The most distinctive sign of a dead hermit crab is a foul stench. Dead hermit crabs smell like rotten fish. If you notice this aroma coming from a tank, it should be investigated immediately.
The reason for this smell is a pheromone released by dying hermit crabs. As per Proceedings of the Royal Society, hermit crabs inadvertently aid each other through scents and pheromones. When a hermit crab is dying, it releases an odor to announce its demise.
This smell alerting other hermit crabs that a shell is becoming vacant. Hermit crabs prefer to live in a shell that was previously populated by another hermit crab. This pheromone release may not be intentional. It’s an instinctive action to propagate the survival of the species.
Be aware that molting hermit crabs can also release this scent. Molting sees an exoskeleton being completely shed. This means that it will start to decay and smell accordingly. Most molting hermit crabs eat this exoskeleton to gain calcium, so avoid removing it.
Equally, molting hermit crabs look to change shell. As hermit crabs grow, they look for new shells. Hermit crabs begin the molting process because they are outgrowing their environment. They abandon shells before they grow too large for them and get stuck inside.
A shell that is unsuitable for one hermit crab is not necessarily useless As long as the shell is not cracked, it can be reused by another hermit crab. So, the shell availability pheromone can be unleashed during molting.
Other Hermit Crabs Gathering
As discussed, dead hermit crabs release a pheromone that attracts conspecifics. These other hermit crabs will line up to try on the now-vacant shell for size. If you notice all your hermit crabs gathering around a prone comrade, it may very well be dead.
Unfortunately, there is a dark side to this behavior. As hermit crabs are omnivorous scavengers, they may start to eat this dead hermit crab. As per the Journal of Experimental Marine Biology and Ecology, hermit crabs can resort to cannibalism.
In theory, this is not a problem. If a hermit crab is dead, why not let its friends eat the body? It will provide fat and calcium, and you won’t need to deal with the corpse yourself. Unfortunately, it is not that simple.
You may not know why the hermit crab died. If it was a result of disease or toxicity, the other hermit crabs could be adversely affected. Before you know it, you will have gone from one dead hermit crab to several.
Also, hermit crabs do not always wait for a friend to die before consuming their meal. Injured hermit crabs are also eaten. This is a defense mechanism from the survivors. They are keen to avoid the scent of a weak and prone crab attracting other predators.
We previously mentioned that hermit crabs should be placed in isolation ahead of molting. This is one of the primary reasons why. Hermit crabs are never more vulnerable than while molting. If your hermit crab was not dead, it may end up that way through a misunderstanding.
Multiple Shed Limbs
Hermit crabs shed limbs and claws for several reasons. To a hermit crab, losing a limb is not the end of the world. They grow back. They often shed limbs when stressed or injured. If you spot this behavior, assess why it happened.
According to the Journal of Crustacean Biology, hermit crabs can regenerate up to 4 lost limbs at a time. This will typically happen immediately before a molt or bring on this action. Hermit crabs losing several limbs at once is rarely a good sign, though.
Limb shedding is a gradual process. If several limbs or claws are lost within 24 hours, it is something more serious. Check for other signs that your hermit crab may have died.
If you are convinced a hermit crab is dead, shake the shell. This will prove your theory beyond doubt. Unfortunately, it could kill a molting hermit crab if it is still alive in its shell. This is why this technique is not recommended.
The thinking behind the shaking method is that live hermit crabs guard their shells jealously. Most hermit crabs would rather shed limbs than be separated from their hard-earned shelter. This means that, if shaken, a live hermit crab will hold on.
Dead hermit crabs lack this ability. The body of such hermit crabs will be loose inside the shell and completely rigid. This means that, in theory, it will fall out of the shell without resistance.
Even this is not a failsafe. A hermit crab may be sick but clinging to life. If the hermit crab was too weak to remain in its shell, you evicted it unwillingly. The shock of this can kill hermit crabs. If it starts to move, allow the crab to return to its shell and leave it alone.
It can sometimes be tough to tell the difference between a molting hermit crab and a dead hermit crab. Only take drastic action if you are certain beyond doubt that a hermit crab is no longer alive.