How Long Can a Hermit Crab Live Without a Shell?


by Simon Griffiths


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Looking at pictures of hermit crabs can be a little bit of a jumpscare for some people, but most people consider these crusty crustaceans as cute. Some people even keep them as pets. So how much do you know about them?

Hermit crabs are unique sea creatures having over 800 different species. While most of them live in the ocean, a good number of them are semi-terrestrial and only one is a freshwater species.

Their uniqueness is attributed to their appearance and mode of survival, and they are actually considered to have more similarities to some lobster species than the average true crab. Hermit crabs have a hard exoskeleton to protect their head and abdomen and a softer exoskeleton on the rest of their bodies.

If you’ve seen one before, you will notice that they have different-looking shells. Interestingly enough, they do not grow their own shells. So where do these shells come from?


Why is a shell necessary for a hermit crab?

Every time you visit the beach, you probably carry a hat for protection, right?

Just like you, the hermit crab considers the beach conditions a tad bit harsh if not hazardous. The hat in their case would be their shell, which is why sometimes they fight over shells, and why shells are in high demand and not easy to come by. 

Shells provide protection against harmful heat, light and air conditions and provide a home during the moulting process.

They also provide extra protective covering for the hard exoskeleton and maintain the required moisture levels that the hermit crab needs.

Hermit crabs are also prone to being feasted on by predators such as seagulls, crows, bigger crabs and fish such as clingfish and snailfish, so they need this shell to protect their softer exoskeleton.

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

Where do hermit crabs get their shells?

Hermit crabs are not born with a shell, making them extremely vulnerable. As mentioned above, the lower parts of their bodies do not have a hard exoskeleton. This brings about the need for a shell to protect their bodies. Hermit crabs use different types of shells as long as they find them suitable.

Some types of shells that they like to use are commonly sea shells, snail shells, and clam shells. The criteria that they use to find a new shell to rehome in is not very complex.

They require a shell that is ;

  1. Big enough to accommodate their bodies comfortably
  2. Has a wide enough entry point so that they can enter and exit with ease.
  3. Is not too big or overwhelming so they can easily carry it around
  4. Hard and strong enough to protect them from the harsh beach conditions.

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

Why would a hermit crab need a new shell?

Hermit crabs can decide to leave their shells for reasons such as 

  1. Irritation caused by debris inside the shell which makes them uncomfortable.
  2. Forced resettlement when crabs fight over a shell and the original owner is displaced.
  3. Outgrowing their shells. Hermit crabs grow very quickly and start to bulge out of their shells. When it starts struggling to get in and out of the shell, it is time for a new one.
  4. Damage to their shells such as cracks leaves them exposed to possible danger. They are very sensitive to their environment so any slight change that affects the suitability of the shell in terms of moisture and heat necessitates a new shell.

What happens when a hermit crab needs a new shell?

Hermit crabs use gastropodal shells, which are not easy to come by. It is for this reason that hermit crabs devise a very intriguing process for rehoming each other.

When one hermit crab decides it is time for a shell upgrade, it plans a synchronous vacancy chain.

What is a vacancy chain, you ask?

This is a system whereby hermit crabs will form a line in an organized manner once they discover there will be a vacant shell. These lines can sometimes have up to 20 hermit crabs looking to find a new shell.

They will arrange themselves in order of sizing, starting with the biggest crab. Once the biggest crab fits the shell and finds it to be a good fit, it will leave behind its old shell for the next biggest crab to try. This process goes on and on, and shells are handed over from one hermit crab to the next and the crabs which are happily rehomed will move along.

This vacancy chain can also take place when a new shell happens to wash up on the shore.

A synchronous vacancy chain is a very effective process of switching shells that benefits many crabs at once ensuring their survival.

Related What To Do When Your Hermit Crab Leaves Its Shell

How Long Can a Hermit Crab Live Without a Shell?

The lifespan of a hermit crab is 15 years if it is well taken care of, but most pet store owners claim that the majority of them do not live more than a year after they are purchased. In their natural habitat in the wild, hermit crabs can live for decades, with most of them living for up to 30 years.

Having explained the importance of a shell, this lifespan is definitely affected in the absence of one. 

There is no definitive length of time that a hermit crab can live without one, but some of them can live for several months. This is of course unless they come across a predator or their living conditions become much too harsh for them to bear.

Related How Does A Hermit Crab Look Without A Shell

Conclusion – how long can a hermit crab live without a shell

In a nutshell (no pun intended), shells are very important to hermit crabs, and they will suffer greatly without them. If you love sea creatures, making sure their shells are in good condition is paramount. This especially goes for those who like to keep them as pets.

Next time you see a beautiful shell with a hermit crab in it, please do not try to remove it for your home decor needs.

The hermit crab really needs it!

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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