Home » Why Do Hermit Crabs Burrow Themselves? [9 Reasons for Digging]
why is my hermit crab digging a hole?

Why Do Hermit Crabs Burrow Themselves? [9 Reasons for Digging]

All hermit crabs like to dig and submerse themselves in the sand. They’re particularly likely to burrow immediately after being rehomed as it’s such a stressful experience.

The most common reason for a hermit crab burrowing is when it’s molting its exoskeleton, which leaves it feeling vulnerable. The hermit crab will remain under the sand until its new exoskeleton has grown.

Other reasons include de-stressing, moderating temperature, foraging, and recreation.

Whatever the reason for a hermit crab’s burrowing, it must be left alone. Never dig up a hermit crab that’s hiding, as it’ll resurface when it feels ready to do so.

Do Hermit Crabs Like to Burrow?

Burrowing is among the most natural behaviors that any hermit crab can indulge in. A habitat must have sufficient substrate to permit multiple hermit crabs to bury themselves, possibly for quite some time.

If hermit crabs can’t burrow, expect your pets to grow distressed. In addition to removing the ability to engage in an instinct, the inability to burrow will impact a hermit crab’s ability to sleep, regulate temperature, and molt.

Six inches of sand in an enclosure will provide enough depth for a typical hermit crab to burrow and bury itself comfortably. Larger hermit crabs will need a deeper substrate and a bigger aquarium, as will sizable colonies of pet hermit crabs.

How Long Do Hermit Crabs Bury Themselves?

If you’re new to owning hermit crabs, you may be surprised at how much time they spend burrowed beneath the substrate in a habitat. If you’re asking, “is it normal for hermit crabs to bury themselves for days?” the answer is yes – within reason.

As we’ll discuss in a moment, hermit crabs bury themselves for various reasons. Sometimes, this burrowing is very short-term, such as searching for food, taking a nap, or looking for privacy from conspecifics for an hour or two.

Equally, hermit crabs sometimes bury themselves for days at a time if feeling overwhelmed and anxious. If the hermit crab is scheduled to molt, it could be 1-2 months before it resurfaces.

Try not to worry about hermit crabs burying themselves. It may initially be frustrating if you want to spend time with your pets, but they’ll eventually emerge. Just give the hermit crabs time and space.

Why Does My Hermit Crab Burrow?

As discussed, there are many reasons why hermit crabs choose to burrow in substrate. In many respects, it’s a purely instinctive behavior carried over from the wild.

It pays to understand why hermit crabs burrow so you know whether to take action. Here are the most likely explanations for hermit crabs burying themselves under the substrate:

1/ Recreation

If you’re wondering, “do hermit crabs dig for fun?” the answer is an unqualified yes. Aside from climbing, digging is one of the most common activities you’ll observe hermit crabs indulging in.

Some hermit crabs seemingly dig holes for the sake of it. The substrate will be smoothed over once done, and the hermit crab will then move on and start exploring elsewhere. More commonly, the hermit crab will climb into the hole, if only for a few moments.

To encourage the ability to dig, choose the substrate of your hermit crab enclosure carefully. Anything too thick will be strenuous for hermit crabs to dig into, restricting their ability to engage in this hobby.

Many owners choose coarse sand for their hermit crabs as this is easy to burrow into and replicates the animal’s natural environment. The sand should be kept moist, although an appropriate humidity level in the tank resolves this issue.

new hermit crab buried itself

How Do Hermit Crabs Dig?

It’s impossible not to notice that hermit crabs have claws of disparate sizes. The larger claw ( known as a cheliped) does most of the digging. The substantial, powerful appendage can move more sand out of the way in one fluid motion.

The hermit crab then uses its second, smaller claw for digging finesse. This claw may be used to move small piles of sand out of the way so the hermit crab can climb into a hole or to move particularly stubborn piles of substrate.

The smaller claw will also be used to cover the hermit crab with sand once it has successfully burrowed. Once the hermit crab feels secure under the sand, it tucks the claws into the shell as a protective barrier.

How Deep Do Hermit Crabs Dig?

Most hermit crabs will dig at least six inches under the substrate of a habitat. In the wild, hermit crabs may go deeper than this, especially if the sun is hot and causing discomfort.

If a hermit crab is larger or has a very prominent shell, it may look to do deeper. A coconut crab, for example, will need at least 12 inches of substrate for digging. As this oversized hermit crab is illegal in the United States, it’s unlikely you’ll need more than six inches.

2/ Foraging for Food

Hermit crabs need a varied diet. Per the Journal of Experimental Marine Biology and Ecology, hermit crabs always gravitate toward food they haven’t recently consumed.

If you provide hermit crabs with the same meal two days in a row, they’ll likely not eat it. Instead, they may bury the food. This ties in with hermit crabs’ nature as scavengers. Wild hermit crabs are not fed – they travel up and down coastlines seeking sustenance.

Don’t encourage hermit crabs to bury food. As well as being wasteful, it’s dangerous. The ideal temperature for a hermit crab enclosure is around 80OF, with 80% humidity. In these conditions, uneaten food will decay quickly, attracting insects and spreading bacteria.

Hermit crabs have hardy stomachs and can tolerate slightly spoiled food, especially fruit. If you’re adding new food to a tank every day, that which has been buried will quickly be forgotten and left to rot.

3/ Anxiety

When introducing a new hermit crab to a habitat, expect it to bury itself for a few days.

Hermit crabs invariably take a while to adapt to changes in their living situation and adjust to life in captivity. This anxiety will manifest as hiding.

Leave it be if your new hermit crab buried itself from the moment it arrived. Continue to take care of your other hermit crabs, offering food and cleaning the habitat according to a standard routine.

It may be several days before you see your new hermit crab. This isn’t necessarily a cause for concern, as there’s every chance the new hermit crab is emerging from under the substrate – it’s just doing so when the home is quiet, and it feels more confident.

If you have a hermit crab that has taken to burying itself for prolonged periods, watch the behavior of your crabs in a habitat. Some hermit crabs burrow as an act of self-defense, hiding from predators.

Is My Hermit Crab Being Bullied?

While keeping multiple hermit crabs in a single tank is advisable, you must ensure they all get along. Hermit crabs are largely docile and friendly, but occasional disputes may arise over territory, mating rights, or superior shells.

If you notice hermit crabs rapping on a shell with their claws, the owner of the shell is being challenged. Another hermit crab covets this protective home and invites the owner to exchange – or fight for the right to wear it.

Some hermit crabs will accept the challenge and wrestle for the shell; others will respond with fear, remaining in their shells and burrowing underground. If the aggressor is particularly bold, it may force the incumbent hermit crab out of the shell.

Observe your hermit crabs as they interact. Hermit crabs amuse themselves and settle shell disputes with tests of strength, including feeler wrestling and pushing contests.

These can be left to unfold without intervention, as a civil resolution will eventually be agreed upon. Behavior describes most hermit crab shell disputes as “a process of negotiation rather than aggression.”

4/ Privacy

Wild hermit crabs live in colonies of up 100. They feel safer and more comfortable among their own kind, so put multiple crabs in a single habitat.

Even the most extroverted hermit crab still needs time alone. Sometimes, hermit crabs will burrow and hide underground for peace and quiet. The hermit crab isn’t necessarily sleeping.

This is especially likely if you keep mixed-sex hermit crabs in the same environment. A male that wishes to mate will rap on the shell of a female, asking her to emerge. If the female isn’t interested, she’ll remain in her shell and seek to escape his attention for a while.

5/ Temperature Regulation

Wild hermit crabs live in scorching conditions, often on beaches.

While shells offer some measure of protection from the heat and UV light of the sun, most hermit crabs spend their days burrowed under the sand to hide from the sun.

Captive hermit crabs will likely have a heat lamp to ensure their habitat reaches the optimum temperature. During daylight hours, many hermit crabs will burrow to stay out of the way of this.

6/ Sleep

One of the most common questions a new owner may ask – “do hermit crabs bury themselves to sleep?” Almost all hermit crabs will burrow and sleep under the substrate during daylight hours.

You shouldn’t disturb sleeping hermit crabs during the day. If you start cleaning a cage or changing the substrate, you’ll likely be pinched by a disoriented and grumpy hermit crab. Wait for your pet hermit crabs to wake up naturally at dusk before attempting cleaning.

If you lay food into a hermit crab enclosure at sunset, you’ll likely find your pets emerging by choice. If the hermit crabs remain sleepy, mist the tank because, as per Proceedings of the Royal Society, higher humidity levels engage a hermit crab’s sense of smell.

7/ Molting

All hermit crabs need to molt occasionally, which will happen multiple times in the first year of a hermit crab’s life, then roughly every 18 months.

Molting is the process of a hermit crab shedding its exoskeleton and regrowing a replacement. Often, it’s accompanied by an increase in size and mass, especially in young hermit crabs.

It can take a hermit crab 4-8 weeks to complete a molt, and it requires complete privacy. If your hermit crab is preparing to molt, move it to an isolation tank where it can burrow and complete the process privately.

Signs that a hermit crab is set to molt include:

  • Skin color fading to gray
  • Eyes growing glassy and dazed
  • Growing tired and showing less interest in play or interaction
  • Eating and drinking more than usual to store fat and water for the long molt

As the hermit crab is devoid of an exoskeleton at times during the molting process, it has never been more vulnerable. This is why molting hermit crabs burrow and prefer to be alone.

Is My Hermit Crab Molting or Dead?

The first time your hermit crab molts can be quite a scary experience. The hermit crab will be buried under the substrate for such a long time that you could understandably fear it has died.

You can’t dig up the hermit crab to see if it’s still alive. In an unwelcome irony, the shock of disturbing a molt could kill the hermit crab. Instead, open the aquarium and take a deep breath. Dead hermit crabs create an unmistakable aroma of rotting fish.

Consider how your other hermit crabs are behaving. As per Ecology and Evolution, hermit crabs are attracted to the aroma of dead conspecifics, so they’ll be keen to see if a now-vacant shell is an upgrade on their own and possibly eat the corpse.

If a hermit crab is molting and not dead, its tankmates will leave it alone. If they’re determined to dig into the same space, there’s a high chance the hermit crab is deceased.

8/ Sickness

Hermit crabs are usually robust if well cared for, but they can occasionally grow unwell.

If this is the case, like all animals, the hermit crab will look for a quiet place to recover and be alone. Typically, this will involve burrowing and hiding under the substrate.

Most health concerns for hermit crabs revolve around an unsuitable environment. Always ensure that the tank adheres to the 80/80 rule – a temperature of 80OF and a humidity level of 80%.

While a hermit crab is active, check its skin, as this is often a sign that something is amiss. So, off hermit crabs a place to drink and bathe. Equally, ensure it’s not infested with parasites. Mites, in particular, can be the bane of a hermit crab’s life.

Hermit crabs can live long lives in captivity. Sadly, like all living creatures, they’ll eventually die. The hermit crab may become more withdrawn and isolate itself when the end draws closer.

hermit crab digging behavior

Do Hermit Crabs Bury Themselves to Die?

If the hermit crab believes it’ll soon die, it may bury itself and pass away quietly and privately. Some hermit crabs vacate their shells when dying, so other conspecifics may use them.

We can’t confidently say whether hermit crabs have a sense of their own mortality, so we can only work on anecdotal evidence. As hermit crabs bury themselves when unwell or frightened, it’s safe to assume that a hermit crab will bury itself before dying.

9/ Attempting Escape

Many hermit crabs climb to the top of an aquarium and hang from the ceiling. Sometimes this is for fun, and sometimes it’s testing for structural weakness in its cage.

Any halfway solid tank should be sturdy enough to keep hermit crabs inside. It doesn’t resolve this issue because your hermit crabs can’t escape. You need to consider why they’re so keen to get away.

Most hermit crabs, while initially cautious, learn to cope with life in captivity as pets. Ask yourself if you are providing your hermit crabs with the optimum conditions, including:

  • A tank large enough to accommodate all your hermit crabs.
  • Appropriate temperature and humidity settings in an aquarium.
  • 12-hour light and dark cycles.
  • Company of non-confrontational conspecifics – remember, hermit crabs are social.
  • Plenty of entertainment, such as climbing toys and hiding places.

All nutritional needs, including a varied diet and additional calcium supplementation, where necessary

If you feel that your hermit crabs have any reason to feel anxious, bored, or stressed, do what you can to rectify this. In doing so, you should cease any escape attempts.

Do Hermit Crabs Burrow with Their Shells?

Most hermit crabs won’t leave their shells for any reason. Hermit crabs look long and hard for the perfect home and are often prepared to fight to maintain it. This means that hermit crabs will almost always bury themselves while still wearing a shell.

If a hermit crab is buried without its shell, it’s likely preparing to molt. When hermit crabs molt, their body mass increases. Leaving the shell, or at the very least sitting half outside it, reduces the risk of becoming trapped in the shell post-molt.

If your hermit crab vacates its shell before burying itself, assess it for damage, as they sometimes abandon cracked or unsuitable shells.

Should I Dig Up My Hermit Crab?

Only one golden rule applies if your hermit crab has burrowed itself under the substrate. Never dig it up, under any circumstances, unless you’re 100% certain the hermit crab is dead.

When hermit crabs burrow, it’s because they’re looking for privacy and safety. Digging the hermit crab up violates this sense of security. It is the equivalent of somebody much bigger and larger entering your home and unexpectedly dragging you out of bed.

You can spot clean the substrate in a hermit crab tank while they’re burrowed if you must but remove the topmost layer. Wait for your hermit crabs to wake up and grow active so you can relocate them before performing a full deep clean.

If your hermit crab has passed away, you’ll have little choice but to dig it up. The habitat will start to smell and attract flies and bacteria if you don’t remove the corpse. Otherwise, leave the hermit crab buried for as long as it wishes to remain this way.

Burrowing comes as naturally to hermit crabs as sleeping and eating, so never attempt to stop your pets from engaging in this behavior. If your hermit crabs burrow underground, assume they’re healthy and happy unless they give you any reason to think otherwise.