Determining whether your hermit crab is molting above ground (surface molt) or has passed away can be challenging, as both states may appear similar. During molting, hermit crabs often exhibit behaviors that might be mistaken for death.
Molting Indicators:
- Lethargy: A molting hermit crab may become inactive, lying on its side with limp appendages.
- Appearance: The crab might partially emerge from its shell, with eyestalks retracted and antennae tucked.
- Substrate Burrowing: Many hermit crabs bury themselves in the substrate to molt safely.
- Exoskeleton Shedding: You may observe the crab shedding its old exoskeleton, which can resemble a deceased crab.
Assessing the Situation:
- Avoid Disturbance: Refrain from handling or moving the crab, as interference can be harmful during molting.
- Check for Odor: A deceased hermit crab typically emits a strong, unpleasant odor, whereas a molting crab does not.
- Observe Subtle Movements: Look for slight movements, such as twitching of the antennae or gill area, indicating the crab is alive.
- Presence of Exoskeleton: Finding a shed exoskeleton near the crab suggests molting rather than death.
Recommendations:
- Patience: Allow time for the molting process, which can take several days to weeks.
- Maintain Optimal Conditions: Ensure appropriate humidity, temperature, and substrate depth to support healthy molting.
In the early stages of the molt, the large cheliped (pincer) becomes somewhat paralyzed as it prepares to pull free of the old exoskeleton. The large shape of the claw must be pulled backwards through the smaller exoskeleton. The soft underlying tissue must be contracted to allow it to pass through the smaller parts of the exoskeleton.
The hermit crabs’ equilibrium gland, called statocyst, is located in the base of the antenna. Like the human inner ear, this gland is responsible for giving the hermit crab balance and the ability to stand, walk and orient itself. During the shedding of the exoskeleton, particularly the antenna, the hermit crab may lose the ability to balance or bring itself upright.
We can see now how molting could be confused for death if the hermit crab appears to be stiff and lifeless. Many molting hermit crabs have been tossed in the trash because their owner believed them to be dead.
One surface molt position begins with the hermit crab lying down on their side while shedding their old exoskeleton. The eyestalks are in a laid down position, antenna appear to be tucked under their eyestalks between the large cheliped and feeding claw in a downward position. The legs appear to be lifeless and very limp with a slight curl. When they lie on their side and are ready to shed their exoskeleton, they come most of the way out of their shells, only keeping the very tip of their tail within the shell. At this time, the hermit crab appears to be lifeless. If one watches long enough and very closely, they will see the hermit crab do an occasional very slight jerk of a body part and a very slight wiggle as they begin to loosen their old exo from the new exo. In between these slight jerks and wiggles, the hermit crab lies extremely still and appears dead, with a very slight occasional movement about their gill area as they take a breath to be able to continue with the deed they must complete. Once the old exo is loosened from the new, the little jerks and wiggles are slightly more noticeable. A brownish/brownish orangey fluid may appear as the old exo splits, and the hermit crab begins the removal of it.
A second molting position that of the hunched hermit crab. Instead of lying down, they are upright in their shell. All of the above observations apply, only the position is different. The molter comes out of their shell to where their first sets of little legs are. As they begin their molting process, they are in the hunched back position.
Another position is molting while in a sitting up. The opening of the shell is facing straight in an outward position. The hermit crabs legs, pincers, and head appear to dangle out of the shell. The eyestalks, antennas, and limp legs, etc. are all observed in the same manner as mentioned in the first paragraph while the hermit crab molts in this position also.
Less common is a hermit crab molting upside down.
In very rare circumstances the hermit crab may leave the shell entirely during molt.
If you are not able to determine if your hermit crab has died or if it is molting the best thing you can do is ensure the hermit crab is safe from its tank mates and wait it out.
For additional information on handling a hermit crab surface molt please read: Hermit Crab Surface Molt
References:
More articles on molting:
What is molting
- Invertebrate Zoology, 7th ed. Robert D. Barnes, Edward E. Ruppert, Richard S. Fox
- Biology of the land crabs Edited by ,
- Invertabrates of the Coral Sea: Dardanu megistos Storm Martin, 2012
