Hermit crabs are rarely regarded as active pets. This is a little unfair as hermit crabs enjoy climbing and playing. All the same, some owners complain that their hermit crabs spend too much time sleeping.
The average hermit crab sleeps for around 8 hours a day. They’re nocturnal, sleeping at night to avoid the sun. Hermit crabs remain in their shells while awake, only growing active when night has fallen.
All hermit crabs emerge from their shells at some stage, as no hermit crab sleeps all day. It may be molting if you haven’t seen a hermit crab in a while.
Monitor your hermit crabs at night and you’ll learn when they emerge and what they do when active.
When Do Hermit Crabs Sleep?
As hermit crabs are popular pets for children, you may ask yourself, “are hermit crabs nocturnal? Do hermit crabs sleep at night, or do hermit crabs sleep during the day?”
As mentioned, hermit crabs are nocturnal. These animals come to life after dark, spending the day hiding from the heat of the sun. This is why hermit crabs often bury themselves under the substrate of a habitat.
Estuarine, Coastal, and Shelf Science confirms that some wild hermit crabs are active during the day. This is based upon tidal patterns, which are irrelevant to captive hermit crabs. Even these wild crabs take refuge from the sun at peak times.
This means that you may wish to consider getting hermit crabs as a pet for children. They are likeliest to be active after bedtime. They will emerge earlier during the winter months but may be completely absent until late at night in the summer.
As a result, think about where to house them. Hermit crabs are not noisy pets, but neither are they silent. They may wake children up by chatting, climbing, and playing at night.
Equally, young children may be unable to interact with their hermit crabs for half the year. This means you will need to step in as a primary caregiver. You’ll need to feed them, clean their aquarium, and handle feeding. Ensure that you are sufficiently prepared for this commitment.
Above all, consider the impact of the hermit crab sleep cycle. Children will understandably want to play and interact with their pets. Hermit crabs are grumpy when roused from sleep, often resorting to pinching.
How Many Hours Do Hermit Crabs Sleep?
Nobody is certain how long hermit crabs spend sleeping. An educated guess points to the standard 8-hour sleep cycle. This does not mean that hermit crabs automatically become active after this period has elapsed, though.
Hermit crabs may choose to remain in their shells upon waking up. They could even stay burrowed under the substrate if this is their bedding of choice. There are many possible reasons for this, including:
- Lack of humidity in the main tank
- Low temperatures in the main tank
- Stress and anxiety (common in hermit crabs that are new to captivity)
- Evasion of other crabs to avoid conflict
- Seeking privacy
- Boredom due to lack of stimulation in the tank
- Excessive light, leading to the crab believing it is still daytime
- Depression (common when they lack the company of their own species)
Some hermit crabs are naturally lazy and lethargic. This becomes commonplace when hermit crabs approach a molt. Be patient and leave your hermit crabs alone. Take a look in their enclosure at night. As long as a hermit crab is showing some signs of life, all is fine.
How Often Do Hermit Crabs Sleep?
Like all animals, hermit crabs require one ‘main sleep’ each day. As discussed, this will unfold during daylight hours. As the sun begins to rise, hermit crabs will instinctively retreat to their designated sleeping spots.
Some hermit crabs also nap at night. It depends on how active they are. Lazy hermit crabs doze more often. These crabs should demonstrate at least some interaction with their environment, though. Watch your crab for movement and engagement.
If a hermit crab does move around, do not panic if it sleeps again afterward. Hermit crabs are small and easily tired, especially if carrying heavy shells. Climbing, in particular, is an exhausting activity. Hermit crabs that climb the walls of an aquarium frequently nap afterward.
Why Do Hermit Crabs Sleep So Much?
It’s hard to know if your hermit crabs are sleeping to excess. They may have been awake for hours. They may just be hiding or relaxing within their shells. Observe other behaviors of your hermit crabs to judge whether you should be concerned. Happy and healthy hermit crabs will engage in the following activities.
- Eating and drinking freely.
- Bathing in saltwater.
- Playing with other hermit crabs.
- Climbing over rocks and scaling tank walls.
- Interacting with other toys.
If one hermit crab isolates itself by choice, refusing to withdraw for its shell, something is up. The hermit crab may be sick. Alternatively, it is concerned about revealing its presence. If the hermit crab has a coveted shell, a dominant tankmate could attempt to steal it.
If multiple hermit crabs spend more time in their shells, it points to an environmental issue. Check the cleanliness, humidity, and temperature of the habitat. Something is making your hermit crabs reluctant to show themselves.
Where Do Hermit Crabs Sleep?
Hermit crabs enjoy a range of different sleeping locales and positions. Most of the time, if you keep multiple hermit crabs together, they sleep in a pile. This is natural. It is a replication of the behavior of wild hermit crabs.
Hermit crabs will almost always sleep within their shells. Vacating a shell at any time is dangerous, especially while sleeping. The hermit crab leaves itself vulnerable to attack, sunburn, or shell theft.
Be alarmed if your hermit crab is leaving its shell. It may suggest the tank is too hot. Check the temperature – it should not exceed 80 degrees Fahrenheit. Ensure that the habitat is not facing a window or direct heat source.
Hermit crabs often crawl under the substrate to sleep, too. This guards them against light and heat. It is also due to the humidity of the aquarium. Humidity is essential to hermit crabs as they suffocate without it. A lack of humidity dries out the gills of hermit crabs.
At the same time, humidity brings hermit crabs to life. Naturally, during sleeping hours, they prefer to feel calm and docile. This means that, by burrowing under the substrate, they are shielded from humidity in the short-term.
Some hermit crabs will sleep in the open. Some even climb to the top of a cage and hang upside down to doze, akin to bats in a cave. This behavior is more common when they need a nap, but crabs seeking privacy and space may adopt this position by day.
Do Hermit Crabs Sleep Soundly?
Life can be dangerous for hermit crabs. This means they rarely fall into a deep sleep, ignorant of what unfolds around them. Hermit crabs remain alert to danger, even while sleeping. In humans and mammals, this would be considered REM sleep.
This is achieved through the antennae of these animals. Hermit crabs do not sleep with their eyes open. They will frequently leave the antennae close to the exit of a shell, though.
As per BMC Neuroscience, hermit crabs use their antennae to detect smells and aromas. Coupled with tiny hairs on the legs, antennae provide hermit crabs with an excellent sense of smell. This is used to warn against predators.
These antennae also remain active during sleep. If you watch your pet doze, you will likely notice the antennae twitching. This ensures the hermit crab will immediately wake and hide if it picks up on a warning scent.
This sense of smell is predominantly reliant on saltwater. Saltwater in the atmosphere stimulates the senses of hermit crabs, making them particularly sharp. If you remove saltwater from an enclosure, hermit crabs will be largely oblivious to their surroundings.
This can be a double-edged sword. On the one hand, it will likely help your hermit crabs get a deeper, longer sleep. It may also plunge them into distress, though. Sleeping without saltwater nearby is like entering a sensory deprivation tank for hermit crabs.
Do Hermit Crabs Dream?
There is no reason to believe that hermit crabs are capable of dreaming. On the other hand, there is no scientific basis to reject this idea outright either. The nocturnal patterns of hermit crabs have never been studied.
Based on existing science, we can base an opinion. Sleep in all mammals and humans is divided into two forms – deep sleep and REM sleep. During deep sleep, the brain is completely inactive while the body repairs itself.
REM sleep, meanwhile, is the brain’s opportunity to sift through memories of the data is processed that day. Important memories about safety and survival are retained. Everything else is discarded.
Now, as discussed, we have no idea if this applies to hermit crabs. What we can say with confidence is that hermit crabs retain memories. Common things that hermit crabs remember include:
- Tankmates and their behavior
- The layout of the territory they inhabit
- Food sources, including what has been eaten recently
- Shells that were previously occupied
As discussed, hermit crabs stay alert while sleeping. This suggests they primarily spend their dozing hours in REM sleep – or at least an equivalent state. Hermit crabs replace damaged or lost limbs during molting, making deep sleep theoretically redundant.
This, in turn, makes it possible that hermit crabs dream. Until modern science grows interested enough to learn more – and invests in equipment to measure brain activity – we cannot say with any certainty.
How to Wake Up a Sleeping Hermit Crab
The short answer to this is that you shouldn’t. Hermit crabs are prone to getting cranky when their sleep is disturbed. Patience is a virtue for hermit crab owners. You’ll need to wait for your pets to wake up and become active at their own pace.
When hermit crabs are asleep, most things can wait. You may be tempted to clean a cage while hermit crabs are inactive. This is inadvisable. You will still disturb your pets. If you are determined to wake them up, try any of the following at your own risk.
- Blow on a hermit crab, or turn on a hairdryer on low heat.
- Place a lively hermit crab next to its sleeping tankmate.
- Pick up the hermit crab and place it in your palm.
- Turn up the heat of a habitat.
- Gently place your hermit crab in saltwater (not too deep as hermit crabs can be sluggish upon waking from sleep and may drown).
Remember what we said – hermit crabs do not like being woken up. At best, you’ll be loudly chirped at for disturbing their slumber. You may also receive a pinch for your intrusion. If you are going to wake up sleeping hermit crabs, keep your hands away from their claws.
Is My Hermit Crab Sleeping, Molting or Dead?
If your hermit crab has not been seen for a while, you may start to worry. This is only natural. Try not to panic. Hermit crabs cease activity for a range of reasons. Learn the signs that differentiate between sleeping, molting and death in hermit crabs.
Sleeping is comparatively simple to determine. Wait until after dark. Your hermit crab may just be a late riser. Take a look at the tank. You’ll likely find the crab going about its business as standard. Alternatively, try one of the wake-up calls discussed above.
Your hermit crab may be molting. This will resemble sleep for a prolonged period – weeks, or maybe even months. When hermit crabs molt, they frequently remain burrowed under the substrate throughout the process.
Rake up a little of the substrate where you believe your hermit crab is molting. If you hear an agitated chirp, it is fine. You are disturbing its molt, so walk away and leave the hermit crab in peace until it re-emerges.
As discussed, molting hermit crabs are often mistaken for dead. Do not assume the worst until all other possibilities are exhausted. Unless there is a foul smell of rotten fish in the tank and other hermit crabs are eating a corpse, your hermit crab is likely alive and well.
Do not be concerned if your hermit crabs spend a lot of time sleeping. As long as they are active at least some of the time, and eating and drinking, they are fine. Hermit crabs are most active while you are fast asleep.