Why Did My Hermit Crab Go Back to His Old Shell?
The most common reason why your hermit crab went back to its old shell is simple: it still feels safest and most comfortable in it. However, several other factors, including molting issues, shell compatibility, and environmental stressors, could also be playing a role.
Introduction: The Perplexing Case of the Returned Shell
Hermit crabs, those fascinating little crustaceans, are known for their nomadic lifestyle, constantly seeking out bigger and better homes. So, it can be quite puzzling and concerning when you observe your hermit crab abandoning a new shell and scuttling back into its old one. This behavior isn’t necessarily a sign of distress, but it does warrant investigation. Understanding the reasons why your hermit crab went back to his old shell is crucial for ensuring their well-being and creating an optimal environment for them to thrive. This article will explore the various factors that influence a hermit crab’s shell choices, providing insights into their complex and often misunderstood behaviors.
Comfort and Security: The Familiarity Factor
For a hermit crab, its shell is much more than just a mobile home; it’s a lifeline. It provides protection from predators, desiccation, and physical injury. A shell that has been previously occupied carries the scent of the crab, offering a familiar and comforting sense of security. Even if a new shell is the right size, it might not feel as safe or secure as the old one, especially if the crab has been in the old shell for a significant period.
Shell Compatibility: More Than Just Size
The size of a shell is obviously important, but it’s not the only factor determining compatibility. Other aspects to consider include:
- Shell Shape: Hermit crabs have preferences for certain shell shapes. Some prefer round shells, while others prefer those with a longer, more spiraled shape.
- Shell Opening: The shape and size of the shell opening are crucial. If the opening is too large, the crab might feel vulnerable. If it’s too small, the crab might struggle to enter and exit.
- Shell Weight: A shell that is too heavy can hinder movement and make the crab more susceptible to predation. A shell that is too light might not provide adequate protection.
- Internal Smoothness: Irritation and discomfort caused by a rough or uneven shell interior is a major reason why your hermit crab went back to his old shell.
- Presence of Damage: Cracks or holes can weaken the shell and compromise its ability to protect the crab.
Molting Problems and Shell Preference
Molting is a vulnerable time for hermit crabs. They shed their exoskeleton, including the part of their body that resides inside the shell. A poorly executed molt can leave the crab feeling weak and insecure. In such cases, the familiar scent and fit of the old shell might offer a greater sense of security than a new, unfamiliar one. Insufficient humidity or improper substrate can contribute to molting difficulties.
Environmental Stressors and Shell Choices
A stressful environment can also cause a hermit crab to revert to its old shell. Potential stressors include:
- Inadequate Humidity: Hermit crabs require high humidity levels to survive. Low humidity can lead to dehydration and stress.
- Incorrect Temperature: Hermit crabs thrive in warm environments. Cold temperatures can slow their metabolism and weaken their immune system.
- Aggressive Tank Mates: If a hermit crab is being bullied or harassed by other crabs, it might retreat to its old shell for protection.
- Lack of Hiding Places: Hermit crabs need plenty of hiding places to feel secure. A bare or sparsely decorated tank can cause stress.
Offering the Right Shells: A Key to Happy Crabs
Providing a variety of shells that meet your hermit crab’s needs is essential for encouraging shell changes and ensuring their well-being.
- Offer a Selection: Provide at least three to five shells per crab, in a range of sizes and shapes.
- Proper Preparation: Boil new shells for five minutes to sterilize them and remove any residual debris. Let them cool completely before placing them in the tank.
- Shell Material: Turbo shells are a common and popular choice, but other options, such as moon snail shells and whelk shells, can also be suitable.
- Shell Placement: Place the shells near the substrate, making them easily accessible to the crabs.
Monitoring Your Hermit Crab’s Behavior
Pay close attention to your hermit crab’s behavior. Is it active and foraging for food? Or is it withdrawn and sluggish? Are there any signs of injury or illness? Observing your crab’s behavior can provide valuable clues about why your hermit crab went back to his old shell and whether any intervention is necessary.
Table: Troubleshooting Shell Switching
| Problem | Possible Cause | Solution |
|---|---|---|
| :————————————— | :————————————————– | :—————————————————————————————————————– |
| Crab consistently returns to old shell | Unsuitable new shells, environmental stress | Provide a wider selection of shells, address any environmental issues (humidity, temperature, tank mates) |
| Crab avoids all shells | Molting difficulties, illness, shell mites | Ensure proper molting conditions, consult a veterinarian, treat for mites if necessary |
| Crab damages or weakens its shell | Nutritional deficiencies, abrasive substrate | Supplement diet with calcium and protein, replace abrasive substrate with a softer alternative |
| Crab displays aggression over shell access | Insufficient shell availability, overcrowding | Provide more shells than crabs, increase tank size to reduce competition |
Frequently Asked Questions (FAQs)
Why is my hermit crab digging a lot after going back to his old shell?
Digging is a natural behavior for hermit crabs. If your crab is digging a lot after returning to its old shell, it could be looking for a place to burrow and molt. It’s crucial to ensure your substrate is deep enough (at least 6 inches) and moist enough to allow for successful molting. Another reason why your hermit crab went back to his old shell and subsequently began digging is because the burrowing helps regulate their body temperature.
Is it normal for a hermit crab to change shells multiple times in a week?
While hermit crabs do change shells, it’s not typically a weekly occurrence. If your crab is switching shells this frequently, it suggests there may be an underlying issue, such as inadequate humidity, inappropriate shell options, or stress. Try to identify and address any potential stressors in the environment.
How can I tell if a new shell is the right size for my hermit crab?
A properly sized shell should allow the crab to retract its entire body inside. The crab should be able to move freely within the shell without being cramped or having excessive space. A good rule of thumb is to offer shells with openings slightly larger than the crab’s largest claw.
What should I do if my hermit crab won’t come out of its old shell?
If your crab hasn’t emerged from its old shell for an extended period (several days), it could be molting, ill, or stressed. Avoid disturbing it. Ensure the humidity and temperature are within the appropriate range, and provide plenty of food and fresh water.
My hermit crab is fighting over shells. What should I do?
Shell fighting is a sign of competition for resources. Provide more shells than crabs, and ensure there are a variety of sizes and shapes available. Increasing the tank size can also help to reduce competition.
How often do hermit crabs need to change shells?
There is no set frequency. Hermit crabs change shells when they outgrow their current one or when they find a shell that is more comfortable or offers better protection. Regular molting necessitates shell changes.
Can hermit crabs share shells?
Hermit crabs typically do not share shells. Each crab needs its own shell for protection and security. Attempts to share often lead to conflict and injury.
What kind of substrate is best for hermit crabs to encourage successful molting?
A mixture of play sand and coconut fiber (Eco Earth) is a popular and effective substrate. The substrate should be deep enough (at least 6 inches) to allow the crabs to burrow and molt safely. It should also be kept moist, but not waterlogged.
How do I know if my hermit crab is molting?
Signs of molting include burrowing, lethargy, decreased appetite, and a milky appearance to the exoskeleton. The crab may also bury itself in the substrate.
Can I paint or decorate my hermit crab’s shell?
Avoid painting or decorating hermit crab shells with anything other than natural, food-grade materials. Toxic paints and glues can harm or even kill your crab. Consider natural decorations like moss.
My hermit crab dropped its claw after changing shells. Is this normal?
Dropping a claw is not normal, but it can happen during a stressful shell change or molting process. If the crab is otherwise healthy, the claw should regenerate during the next molt. Ensure proper conditions to minimize stress.
Why is my hermit crab eating sand after switching shells?
Eating small amounts of sand is normal and helps with digestion and mineral intake. However, excessive sand consumption could indicate a calcium deficiency. Ensure your crab has access to calcium-rich foods or supplements. One of the reasons why your hermit crab went back to his old shell might even be because his current one had the proper calcium on it.