Hermit Crab Without Shell


by Simon Griffiths


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The Hermit crab is a particularly interesting creature because even though they are more similar to some lobster species, they are considered crabs.

Hermit crabs do not have their own shells, so they have to find a shell that belongs to another species. They mostly use sea snail shells or clam shells. Hermit crabs need shells for protection against predators and harsh environmental conditions. Without their shells, their bodies will desiccate and they will die. This is because the moisture hydrates their gills, which they use to breathe. 

Sometimes when they do not find abandoned shells, they will use bottle caps or other plastic covers just so that they do not perish from the harsh tropical conditions. 

Sad, isn’t it? 

From the statement above, it is obvious how badly hermit crabs need their shells, which is why a hermit crab without shell can be cause for concern. For those of you who keep them as pets, you might be wondering why your hermit friend has decided to exit its shell and if it is a bad sign. This article is here to help you.


Why Has My Hermit Crab Left its Shell?

When hermit crabs leave their shells, they become stressed and lethargic because they are exposed to dangerous environmental factors. They will also develop a dry exoskeleton since they are exposed to heat which dries out the exoskeleton.

Sometimes hermit crabs evacuate their shells with good reason. Some of the reasons for shell evacuation are as follows:

1. Unfavourable environment

Hermit crabs need humidity levels of about 70-80% and temperature levels not to go below 75 degrees Fahrenheit. When these conditions are deemed unfavorable, the hermit crab will decide to leave its shell. 

Too much heat will make the hermit uncomfortable and low humidity will make it feel like it cannot breathe. If the humidity is too high, it will also make it difficult for the gills to absorb oxygen so it will leave its shell to decrease it’s discomfort and alleviate it’s stress.

2. Changing shells

Hermit crabs grow quickly, and they need to shed their old exoskeleton to make room for their growing bodies. They will habitually change their shells each time they molt since the old shell cannot fit their bigger bodies. Sometimes when the hermit crab leaves its old shell, it might take a bit of time before it finds a new one that is a good size. 

Gastropod shells are rare in nature, therefore sometimes hermit crabs will fight and injure one another to get the shell. The defeated crab will thus remain without a shell.

Related Are Hermit Crabs Born With Shells Or Where Do They Get Them From?

3. Poor-fitting shell

Sometimes hermit crabs will remove their shells not only when they are too small but also when they are too big or too heavy for them to carry. They need to find a shell that will accommodate their long abdomen and also protect their bodies from the sun and predators.

Related How Do You Remove A Hermit Crab From Its Shell and Is It Safe?

4. Molting

Molting is the process whereby the hermit crab will shed its exoskeleton for a new one and harden it using calcium and chitin some of which is obtained from the old exoskeleton. During this time, they will burrow in the sand for darkness and privacy so that they can secrete the molting hormone. 

While some hermit crabs will burrow their entire bodies including the shell, some of them will leave their shell to molt and reoccupy the shell once the molting phase is complete.

5. Mites and fungus

Sometimes mites and fungi will invade the shell as a result of poor aeration and inhospitable conditions in their habitat. When this happens, the discomfort will cause the hermit crab to move out of its shell.

6. Debris in the shell

Sometimes debris can get into the shell and the hermit crab is unable to clean it out completely with the water in the shell. When this happens, the hermit crab might become agitated and leave its shell temporarily.

Remedies for shell evacuation

1. Modify the habitat

As discussed above, unfavorable habitat conditions will make the hermit crab uncomfortable, because they are very sensitive to temperature changes. Check your thermometer and make sure the temperatures do not fall below 72 degrees Fahrenheit and they do not exceed 80 degrees Fahrenheit.

 The humidity levels should also remain between 70-80%. It is easy to misread a hygrometer because sometimes people place them near the water bowls. The hygrometer should be in the middle of the tank so that the reading can be accurate.

2. Clean shell

You can check the shell and if it has any debris, clean it by dipping it in saltwater and swishing the debris out. Saltwater or distilled water is better to use because tap water is full of toxins and heavy metals which are harmful to the hermit crab. 

Related How Long Can A Hermit Crab Live Without A Shell?  

3. Destress

If the hermit crab is stressed, you can try isolating it and providing it with fresh food and enough saltwater and freshwater. Isolating them ensures that they are not disturbed by other hermit crabs when they are stressed.

Related Why Does A Crab Foam From The Mouth?

4. Rehome the hermit crab

If the hermit crab has left its shell because the shell is too small, you can provide a variety of new shells to try on. To prepare the shells, wash them to remove any dirt or debris and boil them to kill bacteria and germs.

After they are dry, spray them with some salt water.

Leave the shells out in the open where the hermit crab can see them. If it is hesitant to try on the shells try providing fresh food as an incentive.

5. Pest control

In order to tell that a hermit crab has mites, it will have some black or brown flakes on its body. Mites will cause the hermit crab to losing its limbs and it will also cause stress. To treat the mite problem, submerge the hermit crab in dechlorinated salt water. You can also buy medicine for mites that are specifically made for hermit crabs.

 After removing mites from the habitat. Clean and vacuum the tank properly to remove all the mites and boil any toys and accessories to kill the mites.

Related How To Get Rid and Prevent Hermit Crab Mites  

6. Fungus Removal 

The leading cause of fungus and bacterial infection in hermit crabs is poor aeration in the tank and poor sanitation. To prevent and eradicate this problem, ensure that you always use clean substrate in the tank and take out any food that isn’t fresh from the tank every single day.

FAQs – Hermit Crab Without Shell

What happens if hermit crabs get too cold?

Hermit crabs hate the heat, and they definitely don’t do well in the cold either. Too much cold can make them hibernate. In extreme conditions, they will become stressed and die.


If you spot that your hermit crab has left its shell, start by checking if the conditions in the habitat are comfortable. The environment a hermit crab lives in should always be kept ideal so that it lives a peaceful stress-free life. 

Sometimes the hermit crab needs a bigger shell, so it may be time to start shopping.

Simon Griffiths

Hi guys, my name is Simon, a fellow pet lover. I love everything about traditional and exotic pets so I am here to help you create a better home for your pets.

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