Hermit crabs spend most of their time inside shells, enjoying their safety and protection.
All the same, even the most cautious hermit crab should leave its shell occasionally. Not doing so suggests that your hermit crab may be stuck inside its shell and unable to get out.
Hermit crabs may outgrow their shells and find that they can’t escape.
Also, a hermit crab housed in a painted shell can become trapped. If the paint was not completely dry, it may end up glued to its shell.
Of course, your hermit crab may just be more comfortable hiding away inside.
Getting trapped in a shell is life-threatening. All the same, you can’t wrench a hermit crab from its home. Many hermit crabs would rather die than be evicted from their shells.
My Hermit Crab is Stuck in its Shell
To hermit crabs, a shell is a home. They will make do with the one they have. If something better becomes available, they’ll look for an upgrade. So, it can be worrying if a hermit crab remains in its shell.
A hermit crab should leave its residence on occasion, such as when alternative shells become available. If you haven’t seen your hermit crab in a while, it may be trapped.
There are two primary reasons why a hermit crab may become stuck in its shell. It may have outgrown the shell. Alternatively, the hermit crab may be glued to its shell by wet paint. This is common in decorated shells sold by seafront gift shops.
Hermit crabs grow quickly when they’re young. Youthful hermit crabs molt several times a year. Every time the hermit crab molts, it sheds its exoskeleton and develops a new, larger one. Think of the process as the crustacean equivalent of shedding skin.
As a hermit crab grows, it will need a larger shell for protection. A larger opening will also be essential for the hermit crab to come and go. The table below explains the appropriate opening size for hermit crab shells:
|Small:||Opening from 3/8 to 1/2 an inch|
|Medium:||Opening from 1/2 an inch to 1 inch|
|Large:||Opening from 1 inch to 1 and 3/8 inches|
|Jumbo:||Opening of 3 inches or larger|
There is nothing to say that small crabs cannot live in larger shells. As per Biology Letters, hermit crabs adapt to their shells. Movement and lifestyle will be modified appropriately. The larger a shell, the more space a hermit crab has to grow.
What’s more, a larger shell can be an effective trading tool. These animals are often competitive over shells. Nature Communications explains how hermit crabs often trade shells among themselves. Willingly relinquishing a larger shell prevents unwilful eviction.
Often, when a hermit crab outgrows a shell, it cracks it during molting. Once the hermit crab has regrown its exoskeleton, it will find a new, appropriate shell.
This is not always the case, though. If the shell is too tough, the hermit crab may become trapped within. This is uncomfortable, stressful, and dangerous. Take steps to prevent a hermit crab from outgrowing its shell.
How to Tell if a Hermit Crab is Too Big for its Shell
It is advisable to prevent hermit crabs from outgrowing their shells. This means taking action before it’s too late. If your hermit crab welcomes handling, measure it – and its chosen shell.
Hold the hermit crab in your hand and reach for a tape measure or ruler. You are going to measure your hermit’s crab’s largest claw. Once you have this measurement, write it down.
Now, return your hermit crab to its enclosure and wait for it to leave its shell. You will need patience here. Hermit crabs leave their shell on their own terms.
When the hermit crab finally leaves its shell, measure the opening. This must be a minimum of 1/8 of an inch larger than the claw measurement. Anything less will quickly become too small. This creates the risk of the hermit crab eventually getting stuck.
If you are unable to perform these measurements, you could perform a simple eye test. Watch your hermit crab go about its business. If its largest claw cannot retract inside the shell, it is too small. The moment the shell is vacant, throw it away and replace it.
Glued by Wet Paint
Throughout this site, you will notice a common theme. We advise against getting hermit crabs from seafront gift shops. This is because hermit crabs are handled by people with a limited understanding of their needs.
A prime example of this is painted shells. Shopkeepers paint shells all the colors of the rainbow and leave them for hermit crabs. The hermit crab is indifferent to these aesthetic flourishes. It’s a marketing exercise aimed at humans, and it’s undeniably effective.
Sadly, it’s also dangerous. Paint chips are toxic to hermit crabs and create dangerous fumes in humidity. If a hermit crab avoids these fates, wet paint can glue its abdomen to a shell.
This is painful and stressful for hermit crabs. It also makes shell trading and upgrading impossible. Avoid painted shells. There are plenty of naturally beautiful shell designs on any beach.
Is My Hermit Crab Really Stuck?
If you have not seen your hermit crab, do not automatically assume it is stuck. Hermit crabs are shy, docile animals. They are also nocturnal by nature. Your hermit crab may be staying put by daylight and only emerging once it’s dark.
There are other reasons why hermit crabs choose to remain in their shells. Before making any attempt to remove a crab, confirm it is stuck.
Hermit crabs retreat into their shells and hide for several reasons. This behavior is the first step of a process that culminates in burrowing. The hermit crab is keeping its distance from anything that bothers it.
If the hermit crab remains in its shell, it may just be de-stressing. This is common when a hermit crab first enters captivity. It is surrounded by new, unfamiliar stimulation. It needs to take time for itself to adapt.
Equally, the hermit crab may be living in inappropriate conditions. Check the temperature of the tank. This should be around 80 degrees Fahrenheit. Ensure the enclosure has a humidity level of 80%, misting if necessary. Provide appropriate light/dark balance.
You should also check the hermit crab does not feel under threat. As explained by OIKOS, hermit crabs often hide in their shells from protection from predators. Ensure other hermit crabs aren’t bullying it. Keep other pets, like cats and dogs, away too.
As discussed previously, hermit crabs molt regularly. This can be an anxious time for the hermit crab. It will have no protection while undergoing the process. As a result, some hermit crabs choose to molt within their shells.
A molting hermit crab will still burrow. Do not be surprised if the crustacean does not emerge for some time, though. Hermit crabs molt for days, weeks, or even months.
Patience is critical at this stage. A molting hermit crab must be left well alone. Never dig up the hermit crab to see if it is stuck in its shell. The stress this causes can be fatal at such a vulnerable time.
Protecting the Shell
Hermit crabs often squabble and fight over shells. This may result in the hermit crab refusing to leave a preferred home. It worries that, should it do so, the shell will be claimed in its absence.
This does not guarantee the shell will not be stolen. As per Behavioral Ecology, hermit crabs indulge in “shell rapping.” This involves knocking against a shell, trying to loosen the incumbent’s grip. The more powerful the rapping, the likelier it is to be successful.
All the same, a hermit crab will remain in its shell as long as possible. Hermit crabs take shell ownership seriously. Even a docile or small hermit crab will not be evicted without a fight.
Work to minimize the risk of these conflicts and any unpleasant consequences. Provide plenty of shells for all hermit crabs in an enclosure to choose from. This will reduce the chances of one shell being coveted by multiple crustaceans.
Your hermit crab may just be doing what comes naturally. Hermit crabs eliminate inside their shell. Like all animals, hermit crabs feel vulnerable while passing waste. They prefer to poop in their shell, clearing it out later.
If you find plenty of waste in the substrate, there is no need to worry. The crustacean is clearly able to leave the shell and clean up after itself.
How to Tell if a Hermit Crab is Stuck in its Shell
As discussed, not all hermit crabs that stay in their shell are stuck. Your hermit crab may be molting, hiding, or even just relaxing. While hermit crabs often trade shells, this is not mandatory. A crustacean may decide it is happy where it is.
One way to tell a hermit crab is trapped is by watching. If the crab attempts to leave the shell then pulls back, it may be stuck. Test this theory further by placing an irresistible treat on the other side of the tank. Oats are often good for this.
The hermit crab will likely venture toward the food. It may not leave its shell to do so, though. Remember, hermit crabs feel more secure in their shells. A shy or anxious hermit crab will feel particularly unsafe when devoid of protection.
You should be able to tell if the hermit crab is comfortable, though. If it is moving awkwardly, the shell may be too small. Equally, if the hermit crab refuses food, it may be struggling to eat while trapped inside.
Offer a range of new shells of varying shapes and sizes. Place these in a hermit crab’s enclosure while it is burrowed. Check periodically. The hermit crab will eventually grow curious about these alternative accommodations. If not, it’s likely the hermit crab can’t escape its shell.
Helping a Hermit Crab Out of its Shell
If you are certain your hermit crab is stuck, it needs help. Do not rush in and remove it, though. Helping a stuck hermit crab is a delicate process. Learn how to get a hermit crab out of its shell without killing it.
Start by providing more bathing opportunities. Submerging in water douses a shell. This will eventually loosen the grip, especially if the hermit crab is glued inside. If this does not work, you’ll need to take a hands-on approach.
Never tug a hermit crab from its shell. It doesn’t matter how delicate you think you’re being because you’ll end up pulling the legs off. Sadly, a hermit crab would rather be torn to shreds than separated from its shell.
Instead, the hermit crab needs to be gently cut out of the shell. This is a lengthy, painstaking process. Use a blunt, flat-edged knife. If the hermit crab is small, a paperclip may do. Gently slide this around the shell. Expect to be pinched during the process.
You have to be careful here. A hermit crab’s abdomen or eyes can be damaged by being poked. Take your time until your crab is free. If it was stuck, it will emerge to stretch its legs immediately. Throw away the shell so that the hermit crab is not tempted to climb back inside.
At this point, the crab will be stressed and anxious. Ensure it has another shell to climb into that is a more appropriate size and leave it alone. You may find that your hermit crab burrows for a prolonged period of time after this ordeal. It needs to de-stress.
Hermit crabs can get stuck in shells. It’s not common as these animals are governed by self-preservation, but it does happen. Minimize the risk by avoiding painted shells and offering plenty of oversized alternatives. If your crab is stuck, take immediate but careful action.