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Hermit crabs are fun, simple pets that can provide education and companionship to almost any animal lover, and as all hermit crab owners know, there is no hermit crab without a shell!
One of the most exciting parts of hermit crab ownership is picking out new shells for your crab to enjoy, but why exactly are these shells necessary? Most crabs don’t have a shell to live in, so it seems reasonable that a hermit crab might survive without one as well. In reality, having no shell is a death sentence for a hermit crab.
Can a hermit crab live without a shell?
No, a hermit crab can’t live without a shell because of their delicate bodies and the need to keep a certain level of moisture at all times.
Hermit crabs have special requirements to live a happy, healthy life, and that includes the perfect shell. Read on to discover why hermit crabs can’t survive without their shell and the answer to other shell-related crab questions!
Is it Possible for a Hermit Crab to Survive Without a Shell?
Hermit crabs aren’t permanently attached to their shells, and will switch to multiple different shells throughout their lifetimes. In fact, a hermit crab can’t grow to their full size if they stay in the same shell their whole life.
So if hermit crabs can leave their shells to switch to larger shells, is it possible for them to survive without a shell?
No, hermit crabs need a shell at all times for protection. Their lower bodies are very soft and fragile, and without a shell, the hermit crab will swiftly perish.
Most crustaceans have a hard exoskeleton that protects their soft insides, and hermit crabs are no exception, but instead of full body protection, their exoskeleton is only hard on the front half of their body.
For the back half, the hermit crab uses a shell that they have scavenged for protection. Their back half is soft and vulnerable, so the extra layer of the shell is important for the hermit crabs’ survival in the harsh beach environment.
Hermit crabs have evolved a back end that curls to naturally fit the shape of the shell that they choose, making adding the shell onto their bodies effortless.
How Do Hermit Crabs Find New Shells?
Since hermit crabs can’t survive without shells, they have invented unique means of finding the perfect shell once they’ve outgrown their current one.
Hermit crabs occupy gastropod shells, and since gastropod shells are a limited resource, it can be hard for a growing crab to find a new one. Instead of spending an extraordinary amount of time looking for a shell, they will form what is called a vacancy chain.
When a crab needs a new shell and wants to create a vacancy chain to find one, they will exit their shell and wait for it for up to 8 hours. During this time, other hermit crabs will come by to inspect the shell, and if it’s a better fit, move into it.
More than one hermit crab can join this chain. In fact, we have observed vacancy chains of up to twenty hermit crabs! These long lines allow multiple crabs to get new, better fitting homes while also benefiting other hermit crabs.
How to Get a Hermit Crab Out of Its Shell Without Killing It?
Under no circumstances should you try to force or pull a hermit crab out of its shell. The soft lower portion of the crab that is curled around the inside of the shell contains legs, and if you try to pull a crab out, you will pull off these legs and potentially even part of their bodies!
To avoid this grisly fate, if you need your hermit crab to leave their shell, the best way to do it is to tempt them with a better shell.
To accomplish this, provide your crab with numerous shells in a large variety of sizes and shapes. Eventually, your crab will decide one shell is a better home than their current one and leave the old shell, moving into the new one.
Can a Hermit Crab Get Stuck in Their Shell?
If your hermit crab is using a natural, unpainted shell, it’s incredibly unlikely that they are stuck. Your crab may be stubbornly refusing a new shell, or feel unsafe to switch shells, but they aren’t stuck. If you believe your crab is too big for their shell, offer them a bunch of new shells to switch into.
Occasionally, a hermit crab may move into a shell that has been artificially painted. If the paint isn’t completely dry, the crab can become stuck to it once it is completely dried. To prevent this, never use painted shells.
If you believe your crab is stuck, provide lots of warm water for them to soak in. This will make switching shells easier, even in painted shells.
Why Did My Hermit Crab Come Out of Its Shell and Die?
Hermit crabs usually die within their shell, but during molting they can leave their shells and appear dead, so give your crab some time before confirming their death.
If a crab has left its shell to die, it could have been sick, stressed, feeling threatened, or failed to find a new shell in time.
Hermit crabs will sag and fall out of their shells after they die, so it’s possible they passed on and another crab knocked their shell over in their habitat.
What Happens if a Hermit Crab Can’t Find a Shell?
If a hermit crab can’t find a new shell, they won’t leave their current shell.
If they have left their old shell and are without a shell and find their new chosen shell is unlivable, they will move back to the first shell. Rarely, it will take too long for the crab to find a new home and they will perish.
Alternatively, a hermit crab will try to use an object as a shell replacement. We have spotted hermit crabs in laundry detergent caps, metal cans, and even discarded toys!
How Can I Encourage My Hermit Crab to Change Shells?
Hermit crabs will eventually need to change shells multiple times within their lives, but you can follow a few steps to make them more likely to switch sooner rather than later.
- Provide a lot of new shell options
- Make sure your hermit crab is comfortable and doesn’t feel threatened
- Keep your hermit crabs water full and clean so they can soak themselves to prepare for switching shells
How Do Hermit Crabs Get Their First Shell?
Hermit crabs are born without a shell in a larvae form, but when it’s time to find a shell, they will seek one out themselves or join a vacancy chain.
Do Hermit Crabs Poop in Their Shells?
Yes and no. Hermit crabs poop from a small opening in the bottom of their abdomen, but they quickly sweep the food out with their small back legs so the poop never remains in the shell.
Do Hermit Crabs Need a Heat Lamp?
Hermit crabs need a heat lamp if the temperature in their habitat dips below 70° F ° (21 C).