Hermit crabs are popular pets that are becoming quite common. You might have recently started caring for your own pet hermit crab.
They’re so much fun to observe and take care of. If you properly care for these pets, they can stay alive for a long time.
As you’d expect, things can go wrong from time to time. If you’re noticing that your hermit crab is outside of its shell or partially outside of its shell, you’re likely going to be worried.
Normally, hermit crabs don’t like to leave their shells. A shell provides protection for a hermit crab and makes it feel safe.
Why is your hermit crab outside of its shell? Has the hermit crab died?
Read on to learn about what might be going on. This should help you to figure out what’s happening and what the best course of action is.
Why Would a Hermit Crab Leave Its Shell?
Under normal circumstances, a hermit crab wouldn’t leave its shell. Typically, these creatures are going to stay in their shells unless something is really wrong.
There are some reasons why hermit crabs might have to leave their shells from time to time. Some of them are normal, but others indicate that there’s a serious problem.
Below, you’ll find information about several reasons why this might occur. Once you’ve read everything, you’ll have a better idea of what’s going on with your hermit crab.
It’s possible that your hermit crab is experiencing any one of these things. You’ll simply have to observe the hermit crab and use the context of the situation to determine what’s going on.
1 – Molting
Hermit crabs molt every so often because they grow. When hermit crabs grow, their exoskeletons do not grow with them.
Thus, they’re forced to shed their outgrown exoskeleton and grow a new one. The molting process allows hermit crabs to grow new exoskeletons.
This is a process that can take quite some time. It’ll take weeks or potentially over a month for a hermit crab to finish molting.
During this time, the hermit crab is going to bury itself in the sand. After the hermit crab is done molting, it’ll need a new shell.
The hermit crab is larger, and it’s going to need a bigger shell now. This means that the crab must leave its shell to enter a new one.
There are times when hermit crabs will have trouble choosing a new shell. It might keep going back and forth between shells trying to make a decision.
Just ensure that you have many shells in the habitat for the hermit crab to choose from. It should have various shell sizes to consider, and it’ll eventually find what it needs.
If this is what’s happening, you don’t have anything to worry about. However, there are many other possibilities to consider.
2 – Excessive Stress
There have been instances where hermit crabs have come out of their shells for strange reasons. Did you know that you can cause hermit crabs to act strangely by exposing them to many stressful situations?
In some cases, excessive stress might cause hermit crabs to leave their shells. Generally, this isn’t something you’ll see hermit crabs do, but it might happen in extreme situations.
Some hermit crab owners have reported shell evacuation being a response to excessive handling. Handling is a stressful thing for hermit crabs to deal with.
It’s not recommended to handle a hermit crab more than is necessary. Hermit crabs can kind of get used to being handled, but it isn’t something they particularly enjoy.
Often, hermit crabs get scared while humans are handling them. They try to pinch humans in response when they get too frightened.
Even when handling hermit crabs properly, it’s still not wise to handle them too much. You should keep handling to a minimum.
Excessive handling might cause shell evacuation. So can excessive transportation.
If you’ve been moving a hermit crab around a lot, this might make it feel stressed. That’s also known to cause hermit crabs to leave their shells.
So pay attention to what you’re doing and try not to stress your pet crab. If you’ve been handling your pet too much lately, it might be beneficial to tone things down.
3 – Problems with Humidity in the Tank
Humidity is something that you must pay attention to when caring for hermit crabs. You need to use a hygrometer to check the humidity levels in the habitat.
To keep things safe for the hermit crab, you’ll need to keep the humidity between 70% and 80% in the tank. Doing this isn’t too tough when you’re using a humidifier, but you still need to monitor the situation.
If the humidity is too low, it’s going to cause the hermit crab to have breathing difficulties. It’ll eventually kill the hermit crab because it won’t be able to breathe.
Hermit crabs have modified gills that can breathe oxygen, but they must stay moist to be able to do so. Thus, humidity is of the utmost importance.
Sometimes improper humidity levels will cause shell evacuation. Check the humidity level in the tank to see if you need to make adjustments.
4 – Problems with the Temperature in the Tank
The temperature being too hot or cold in the tank can be bad for hermit crabs, too. Hermit crabs need to be kept in warm temperatures, or they won’t do too well.
Generally, it’s necessary to keep the temperature in the habitat between 72 degrees Fahrenheit and 80 degrees Fahrenheit. If you do this, the hermit crabs should be safe.
Cooler temperatures are bad for hermit crabs, but so are temperatures that are too hot. Hot temperatures can potentially dry the hermit crabs out.
You already learned the importance of gill moisture when it comes to hermit crabs. It’s also imperative to keep the crabs comfortable.
Having the wrong temperature in the tank might cause the crab to leave its shell. Always monitor the temperature using a thermometer to be safe.
5 – Hermit Crabs Fighting Each Other
There could be a situation in your hermit crab tank where the crabs are fighting each other. Typically, hermit crabs are known to get along well, but they might fight for one reason or another.
Sometimes hermit crabs will fight each other for shells. One hermit crab might covet the other’s shell, and this will cause a fight.
A hermit crab might be forced out of its shell due to fighting with another crab. You can prevent issues such as this by keeping multiple shells in the habitat.
Always ensure that there are multiple shells of the same size in the tank. This should keep the hermit crabs from feeling as if they need to fight to find the perfect shell.
6 – Fungal Growth Issues
There have been situations where hermit crabs have had to leave their shells due to fungus growing inside the shell. This is a bad situation, but it’s something that you can prevent easily enough.
To prevent issues with fungal growth, you want to ensure that there’s proper airflow in the tank. This should limit the chance of fungal growth occurring in the habitat.
It’s also best to feed your hermit crab fresh foods. Remove any leftover food so that it won’t contribute to problems with fungal growth.
If there’s already fungus in the tank, you’ll need to clean the tank thoroughly. Replace the sand in the tank and boil rocks, gravel, and decorations to be safe.
You can try to clean the shells and then boil them for five minutes. You must rinse the shells after this and allow everything to cool before putting the shells back in the tank.
7 – Bacterial Infections
Bacterial issues are actually quite similar to the problems with fungi described above. It’s easier for bacteria to grow in a hermit crab tank when the conditions are humid and the airflow isn’t good.
You might not be cleaning the tank regularly enough. Try to pay more attention to cleaning the substrate material.
Also, it’s best to monitor the condition of the water in the tank. The shallow dishes of water should be emptied and replaced with fresh water every so often.
Otherwise, you might wind up dealing with mold and algae growth. Better cleaning and tank maintenance will help to prevent problems with bacterial infections in pet hermit crabs.
8 – Sand in the Shell
There have been times when hermit crabs have left their shells due to excessive amounts of sand being in the shell. Sometimes sand might get in the shell for one reason or another.
Sand is an important part of a hermit crab’s habitat. It’s normal for sand to be present, but sometimes the sand might get stuck in the shell.
Having sand in certain spots might be uncomfortable for the hermit crab. It might leave the shell in an effort to remove some of the sand.
This likely isn’t anything to worry about. It should be something that the hermit crab can solve on its own.
9 – Mite Infestations
Mite issues are a much more serious thing. Mites are pests that can bother hermit crabs.
They will get all over the hermit crabs’ bodies and will cause them to feel unwell. You want to solve issues with mites as soon as you recognize them.
The problem is that mites are rather tiny and can be hard to see with the naked eye. You might need a magnifying glass to notice them.
Removing mites is easy enough, but you will want to do things the right way. The hermit crab should be removed from the tank so you can clean it.
Clean the tank thoroughly and remove the sand and other substrate materials. Throw the old sand away and boil any gravel that you have.
You’ll also want to boil decorations, rocks, and other such materials. Clean the tank very well and then rinse it off.
It might take several attempts to get the job done. Be thorough, and you should be able to get rid of the mites.
Hermit Crab Out of Shell Looks Dead
Sadly, if your hermit crab is out of its shell and it appears to be dead, it very well might be. Try to determine if the hermit crab is living or not.
If the crab is molting, you want to leave it alone. However, you should be able to tell the difference between molting and a dead crab.
A dead hermit crab will smell horrible. Dead hermit crabs are known to smell like dead or rotting fish.
The smell will be so severe that you’ll likely notice it easily. In this situation, something might have killed your crab.
It could be that the crab was exposed to chemicals or it might have simply not been cared for properly. Either way, all you can do is dispose of the body now and clean the tank.
Now you know about several reasons why hermit crabs might leave their shells. Sometimes this occurs because a hermit crab is uncomfortable.
It could have some sand stuck in its shell. Perhaps the shell has bacterial or fungal growth issues.
Try to examine the situation so you can determine what’s going on. The hermit crab might even simply be in the process of switching shells.
Hermit crabs shouldn’t stay out of their shells for too long, though. If your hermit crab is motionless outside of its shell, there’s a chance that it might simply be dead.
Since dead hermit crabs smell very bad, it’s usually not too hard to tell. A dead hermit crab smells like a dead or rotting fish.
Do your best to care for your hermit crabs to keep them from experiencing problems. Monitor the temperature and humidity of the tank.
Clean the tank well to avoid issues with fungal or bacterial growth. If you suspect that mites are a problem, act fast to fix things.
You know what to do now. It should be possible to turn things around if you take the right actions.
Jeff has always enjoyed having pets, but as a child, he was drawn to his family’s fish tank. Being able to maintain a small ecosystem and observe the behaviors and interactions in the underwater world peaked his interest early on and has kept him hooked until this day. On Avid Aquarist, Jeff shares everything he’s learned about helping aquatic life survive and thrive in a home aquarium.