A hermit crab’s shell serves two essential purposes: protecting its soft abdomen and preventing it from drying out. When a hermit crab abandons its shell, it’s a clear indication that something is wrong. Here are several possible reasons why your hermit crab is out of its shell:
Table of Contents
Causes for a Hermit Crab Leaving Its Shell
Physical Stress
Land Hermit Crabs endure significant stress during the capture, transportation, and pet store handling processes. Unfortunately, many pet stores lack the knowledge to properly care for these creatures. As a result, hermit crabs often arrive at their new homes dehydrated, hungry, and extremely stressed. In such cases, leaving the shell is often a sign that the hermit crab is too physically damaged to survive.
Shell Fight
If there’s a lack of appropriate styles and sizes of shells in the hermit crab’s environment, they may engage in shell fights. These fights can be dangerous and even fatal for the hermit crabs involved, as they are reluctant to give up their protective homes. Sometimes, a hermit crab may drop its shell to try on a different one, only to have it taken by another crab. When suitable shells are scarce, the hermit crab is left homeless.
Foreign Body/Irritant
Sometimes, something may have entered the hermit crab’s shell and is irritating its soft abdomen. Rinsing the shell with dechlorinated water can help dislodge any foreign bodies. However, in cases where something is lodged deep within the shell or if there are pests or fungus present, rinsing alone may not be sufficient.
Incorrect Environment – Temperature and Humidity
If the temperature is too high, a hermit crab may leave its shell to cool off. It is crucial to monitor both the substrate and air temperatures. The warm end of the crabitat should ideally be around 80-82°F, as temperatures above 85°F can be uncomfortable for most hermit crabs. Similarly, if the humidity level is too low, the hermit crab may feel suffocated and abandon its shell. On the other hand, excessively high humidity levels can cause breathing difficulties and even gill infections.
Pre-Molting
Although rare, a hermit crab may leave its shell if it is in the pre-molting stage or currently molting.
How to Encourage a Hermit Crab Back Into Its Shell
- Start by washing your hands.
- If the hermit crab has shed its exoskeleton or is in the middle of molting, refer to the NOTE section below.
- Rinse or boil the abandoned shell in dechlorinated water to remove any lodged irritants. Place the shell at the bottom of a cup or small bowl, just big enough for the crab and the shell. Add a small amount of dechlorinated water to keep the crab moist and increase the chances of re-shelling.
- Gently pick up the hermit crab from behind the last pair of walking legs or use a large spoon to scoop it up. Be cautious not to injure the crab while examining its abdomen for signs of irritation or molting symptoms.
- Carefully lower the hermit crab into the cup next to its shell. Cover the cup with a washcloth to create darkness and transfer it to an isolation unit with suitable temperature and humidity conditions, or return it to the main tank. Ensure that other crabs cannot access the cup.
- Leave the hermit crab undisturbed in a dark and quiet environment for about an hour. During this time, it may return to its shell.
- If the crab remains naked, you can move it to a slightly larger containment area, such as a small kritter keeper. Add more shells that might fit the crab’s size. Offer foods like greensand, worm castings, scrambled eggs, or other favorites to encourage eating. If the crab is lethargic and not eating, try offering a small amount of honey on a toothpick. Do not force-feed the crab. Place the kritter keeper inside the isolation tank or the main tank, ensuring the crab has proper heat and humidity levels.
- If the crab still refuses to take a shell, there is little else to do except keep it comfortable and wait. Continue offering food and water while maintaining appropriate humidity and temperature levels.
NOTE: For molting or recently molted crabs, follow a different approach. Use the 2-liter bottle method to isolate the crab within the tank. However, be aware that this method does not protect against crabs digging in from below. If other crabs show excessive interest, transfer the molting crab to a secure container within the tank. Avoid adding water due to the crab’s soft exoskeleton. The crab will likely be exhausted and unable to accept a new shell until it has fully hardened and regained energy. Provide the most recent shed exoskeleton, along with water and appropriate foods. Refer to our Hermit Crab Feeding Guide for the best food options during this time.
If you need further assistance, please refer to the Emergency Help Article or visit 5 WS for more hermit crab-related information.
