It takes hermit crabs a while to adapt to life in captivity. Even then, hermit crabs won’t always welcome attention. You may find that your pet hermit crabs are shy and spend most of their time hiding.
Hermit crabs are nocturnal animals, so they’ll spend most of the day under the substrate. At this point, hermit crabs won’t be active or move. Hermit crabs usually rise at sundown, looking for food.
All hermit crabs hide for the first few weeks of captivity, known as post-purchase stress. Hermit crabs that have adapted to life as pets should be more active at night. Something is amiss in their environment if your hermit crabs are always hiding and never come out.
Hermit crabs hide when stressed and upset. Potential causes include the wrong temperature, external stresses such as noise or other pets, or aggressive behavior from other hermit crabs. Equally, hermit crabs start hiding ahead of molting their exoskeleton.
What Time Are Hermit Crabs Most Active?
Wild hermit crabs are most active at night, primarily for their protection.
The sun’s rays can be harsh in the tropical climes that hermit crabs hail from, while many beaches that host them are much quieter after dark.
Most hermit crabs spend their days hiding under the sand, sleeping during daylight hours. Once the sun goes down, hermit crabs will emerge hungry and start scavenging for food.
This habit will carry over into captivity, so ensure your hermit crabs have an appropriate balance of light and dark, and you’ll start to see them more at sundown.
Place food in the tank before your hermit crabs awaken and emerge from the substrate.
I Never See My Hermit Crabs Eat
Early evening meals should be enough to tempt hermit crabs out of hiding.
If your pet hermit crabs never seem to emerge, walk away and check back later. If the food is disturbed and eaten, the hermit crabs are still shy and prefer to eat alone. You need to earn their trust.
If your hermit crabs aren’t touching their food, something is amiss. If you have one hermit crab, it may be molting. Multiple hermit crabs not eating will be due to the following:
- You’re serving the same food as the day before. The Journal of Experimental Marine Biology and Ecology explains how hermit crabs dislike eating the same food twice in 24 hours.
- This food has been consumed previously and caused distress for the hermit crabs. As per The Biological Bulletin, hermit crabs learn from negative experiences.
- The hermit crabs are uncomfortable entering the open and eating due to external stressors.
- The food doesn’t carry a strong scent, as hermit crabs smell food with their antennae.
- You haven’t added enough saline water. As per BMC Neuroscience, this stimulates a hermit crab’s sense of smell.
Fix these issues, and you’ll find that your hermit crabs willingly emerge from their hiding place and eat their meals at sunset.
Why Is My Hermit Crab Hiding?
A hermit crab may remain static under the sand, not active or moving, or it’ll surface from the substrate but hide within its protective shell.
Post-Purchase Stress
Post-purchase stress (PPS) is common because they’re initially ill-equipped for captivity. They have been taken from their home and colony on the beach and find themselves in an artificial environment.
After bringing them home, don’t expect to see your hermit crabs for a while. You may not see them at all, as PPS claims the life of some hermit crabs that can’t adapt.
Those that survive will eventually find the confidence to explore their new home.
How Long Do Hermit Crabs Hide When New?
There’s no single length of time that can be assigned to PPS. Some hermit crabs recover in days; others take months to come to terms with their new surroundings.
Expect hermit crab to hide under the substrate for two weeks before surfacing. The closer the conditions of a habitat mirror a hermit crab’s wild environment, the sooner it’ll gain confidence and cease hiding.
Inappropriate Habitat Environment
Hermit crabs need to live in an environment comparable to their wild habitat. This means that a tank must offer the following:
- Temperature of around 80OF. If a hermit crab is too hot, it’ll hide under the substrate to protect itself. A hermit crab will hide in its shell and cease moving if too cold.
- A humidity level of 80% because hermit crabs need humidity to keep their gills moist and breathe easily. If your hermit crab starts to suffocate, it’ll panic and hide.
- Recreational activity for hermit crabs, especially climbing apparatus. If your hermit crabs are bored, they’ll grow stressed and hide under the substrate.
- An appropriate balance of light and dark. Circadian rhythms govern hermit crabs, so they rely on darkness to understand it’s time to get active.
Setting up the perfect habitat for hermit crabs should always be your priority.
External Stressors
If something in your hermit crab’s external environment is causing stress, they’ll remain in hiding. Common examples of external stressors for hermit crabs include:
- Excessive handling – only pick up your hermit crabs when unavoidable.
- Other pets such as cats or birds circling a tank.
- Noise beside and around the tank. Behavioral Ecology explains how noise can disorient hermit crabs.
Maintain a calm and peaceful ecosystem for your hermit crabs if you want to see them exploring and enjoying a habitat. The surrounding territory is just as important as the tank itself.
Unwelcome Attention from Other Hermit Crabs
Hermit crabs get along, but disputes and disagreements will always arise. Captive hermit crabs have limited opportunities to escape aggressive or persistent conspecifics, so they may choose to hide instead.
This hiding will usually involve staying still. If you ask yourself, “why does my hermit crab stay in its shell?” there’s every chance it avoids conflict with a tank mate.
Marine and Freshwater Behavior and Physiology stated that hermit crabs could recognize each other by scent. This means one hermit crab may regularly hide to avoid a dominant rival.
Even friendly hermit crabs can come into conflict over shells. If a hermit crab harbors a shelter coveted by another, the latter entrant will issue a challenge, often involving a test of strength. The incumbent hermit crab may hide to avoid this challenge, especially if it fears losing.
Female hermit crabs also hide to avoid mating advances from males. Hermit crabs enter heat for around four days at a time, releasing pheromones throughout this period. If the female isn’t interested in mating, she may hide from males until this time passes.
Molting
If a hermit crab is molting its exoskeleton, it’ll hide under the substrate and fail to surface until the process is complete. Molting is a wholly personal experience for hermit crabs, so a molting hermit crab should be moved to an independent tank ahead of time.
When a hermit crab molts, it sheds its existing exoskeleton and grows a replacement, typically a larger one that accommodates an increase in body mass. This is a vulnerable time, so the hermit crab isn’t to be disturbed under any circumstances.
Hermit crabs know when a molt is impending, often filling their shell with water and stocking up on food. The hermit crab can remain in hiding for several weeks or even months. The hermit crab will show itself when it feels confident doing so post-molt.
Hermit crabs should be expected to hide during the day, but pay attention if they don’t become active at night. You need to consider what could upset your hermit crabs and work to build their confidence. Happy, confident hermit crabs will become active and visible after dark.
