How Often Do Hermit Crabs Change Shells?

Hermit crabs are fascinating little creatures that have a unique requirement – they need empty seashells to use as mobile homes. Unlike other crabs, hermit crabs cannot grow their own shells, so they depend on finding and occupying empty shells left behind by other animals. This brings up an important question for hermit crab owners: how often do hermit crabs change shells as they grow?

Why Hermit Crabs Change Shells

Hermit crabs change shells for a few key reasons

Growth: As hermit crabs grow, they need to switch to larger shells to accommodate their increasing size. Hermit crabs grow through a molting process where they shed their exoskeleton. After molting, they are noticeably smaller and can even fit into smaller shells temporarily before growing into a larger size again.
Shell condition: Hermit crabs may abandon a shell if it becomes damaged, eroded, covered in algae/debris, or otherwise unsuitable. They will seek out a new, cleaner shell.
Shell preference Hermit crabs have personal preferences when it comes to shell shape, weight, size, and more They may switch shells in search of one that is more ideal Some hermit crabs enjoy changing shells frequently.
Availability An abundance of empty shells in the crabitat triggers more frequent changing as crabs explore the options A lack of empty shells causes them to keep their current shell longer.

Frequency of Shell Changes

So how often do hermit crabs actually change shells? There is no set schedule, but here are some general guidelines:

Before/after molting: Most hermit crabs molt every 12-18 months. Shell changing often happens just before or after a molt as the crab switches to an appropriately sized shell.
As they grow: Aside from molting periods, hermit crabs change shells as they grow throughout the year. Young, rapidly growing crabs may switch shells more frequently.
When housed properly: In a well-maintained crabitat with adequate empty shells available, hermit crabs may change shells multiple times per week, whenever the mood strikes.
When shells are limited: With fewer shells to choose from, hermit crabs will keep their current shell longer out of necessity. But lack of shells can inhibit growth.
Species differences: Some species like Purple Pincher crabs change shells readily when given options. Ecuadorian crabs are more reluctant to switch.

Encouraging Shell Changes

While shell changing happens on the crab’s schedule, you can provide ideal conditions to make it easier whenever they are ready:

Offer multiple shells – Provide 3-5+ options per crab, in natural materials, free of debris/odor, and with openings 1/8 inch larger or smaller than their current shell. Rotate shells out periodically to spark interest.
Choose shell shapes – Match shapes and openings to their preferred shell types (rounder for Caribbean species, flatter for Ecuadorians).
Maintain humidity – Humidity over 75% helps crabs stay hydrated for safe shell changing. Provide deep substrate and moist moss pits.
Give hiding spots – PVC hides, cholla wood, and leaf litter give crabs secure spots to change shells safely.
Keep crabitat clean – Remove moldy food, flood pools, and waste to prevent bacteria/unsafe conditions when vulnerable out of shells.

Signs a Shell Change is Needed

Here are signs your hermit crab has outgrown its current shell:

Tips of legs or claws visibly sticking out of the shell opening
Inability to fully retract into the shell when picked up
Shell fits loosely and rattles when crab moves
Lack of growth over a long period of time
Constant climbing or hanging out of the shell

If you notice these signs, it is important to provide extra shells ASAP so your crab can safely switch. Avoid forcing them out of shells; they will resist and can be injured. With the right shell options, they will change shells on their own.

The Shell Changing Process

When hermit crabs decide it is time for a new shell, here is how they go about it:

They will start exploring empty shells in their environment, testing out new options.
When they find one they like, they partially back out of their old shell and start trying on the new shell for size.
Once the fit seems right, they fully exit the old shell and quickly enter the new, preferred shell for protection.
They may further adjust/modify the new shell by scraping out debris or shaping the opening.
Within a few days, the hermit crab will fully settle into its new shell.

It is normal for them to re-visit old shells or try out multiple new shells before deciding. Provide extra shells so they always have options.

While there is no set schedule, hermit crabs frequently change shells as they grow. Expect them to switch shells at least every 12-18 months before and after molting. Beyond that, the frequency varies based on species, age, growth rate, and availability of empty shells. Create ideal conditions and let your crabs change shells as often as they need. With the right habitat and shells, they will thrive!

how often does a hermit crab change shells

Encouraging your hermit crab to change shells

Sometimes, your crab may seem like he or she just does not want to change their shell.

You can’t exactly force it to happen. A hermit crab would sooner let itself get torn in half than be forced out of its shell.

Instead, you need to prepare and make sure your crab has everything it needs to change shells.

First, as mentioned before, you need the right shells. Remember that Ecuadorian crabs need shells with a thinner, more narrow shell and Carribean crabs need a round, oval-shaped opening.

Painted shells are a no-go. The paint could chip off the shell and harm your hermit crab!

You should have at least 3 extra shells per hermit crab. I recommend having one a bit smaller, and one a bit larger than the crab’s current shell. This gives your crab plenty of flexibility when choosing its shell.

Lastly, make sure you keep the extra shells clean. Boiling the shells for 15-20 minutes every other month will keep them free of bacteria and dirt. Just make sure you check inside each shell! You don’t want to boil your crabs!

You cannot predict when your hermit crab will change its shell. Instead, prepare for when it does happen. Give your crabs plenty of extra, clean shells that are the right size.

When your hermit crab inevitably does change shells, write it down on your calendar. Maybe you will see a trend and be able to predict its next shell change.

Hermit crab shell changing habits

In a perfect world, we could predict when our hermit crabs would change shells and how often to make our jobs as pet owners much easier.

It turns out that there’s no way to predict when a hermit crab will change its shell. It’s entirely up to the hermit crab when and where it changes its shell for a new one.

There are, however a few factors that can give you an idea of how often your hermit crabs will change shells. Here are two:

Some species of hermit crabs like to change shells more frequently than others.

For example, the Carribean Hermit Crab (also known as a Purple Pincher Hermit Crab) is very inclined to changing its shell.

Whenever a Purple Pincher stumbles upon a shell that’s, in its opinion, better than its current, it will change shells then and there. Sometimes they can be indecisive and switch back and forth until one feels right.

Other hermit crab species choose not to switch shells as often. The Ecuadorian Hermit Crab is very hesitant when it comes to changing shells.

These finicky little creatures only change shells when they absolutely need to, usually when they’ve entirely outgrown their previous shell.

Everyone has his or her own reason to why this is the case. Some say this is because of the Carribean and Ecuadorian crab competing for the same type of shell, which is not the case.

According to hermit-crabs.com, Ecuadorian crabs need shells that are a bit different than the average Caribbean’s. Ecuadorian crabs are much flatter and wider than other hermit crabs, which makes them look for a shell with a flatter, coin slot-shaped entrance.

This is much different than the usual round or oval-shaped shell openings most Purple Pincher Hermit Crabs are used to.

Maybe this is the reason why Ecuadorians are very picky when it comes to choosing shells. In any case, be sure to supply your crab with at least 3 shells, some a little smaller and others a little larger than their current shell.

Hermit Crab changing shells

FAQ

How do you know your hermit crab needs a new shell?

When a hermit crab is about to molt, you may notice an increase in food and water consumption. Sometimes they’ll drink an excessive amount of salt water, and seek out more high protein foods than usual. They may begin digging holes all over the tank and even stay in them periodically to test them out.

Should I remove my hermit crab’s old shell?

It is actually best that you do leave the old shell in there, even if it’s to big or too small. Like Kamira said, sometimes they just like changing shells when theit bored.

How do I tell if my hermit crab is happy?

Signs of a happy and healthy crab include. Active – your crab is actively exploring their tank and using their enrichment activities.