The moulting process of a hermit crab is a sensitive procedure that ideally occurs completely below the substrate. Regrettably, this is not always the situation, and occasionally, your hermit crab may moult above the surface.
This situation requires immediate attention as it could potentially be a life-threatening emergency if not addressed promptly.
As Arthropods, hermit crabs undergo molting as a necessary process for growth. For detailed information on hermit crab molting, please refer to our dedicated post.
Meanwhile, let's delve into the topic of surface molting.
What exactly does surface molting entail?
Surface moulting occurs when a hermit crab undergoes the moulting process above the substrate and in plain view. This behavior can be highly dangerous and, if not managed correctly, may result in fatal consequences.
The decision of hermit crabs to undergo surface moulting instead of moulting beneath the substrate is influenced by a myriad of factors. Surface moulting is typically considered a less favored option and is often resorted to as a final solution.
Below are some reasons as to why a surface moult may occur.
Inadequate Substate Depth - Adequate substrate depth is essential for Australian hermit crabs, with a minimum requirement of 6 inches (15cm). This depth allows them to safely dig down and molt without the risk of being discovered and attacked by potential intruders. It is common for hermit crabs to utilize the full depth of the substrate and molt at the tank's deepest point. If possible, providing a depth greater than 15cm is advisable. Having insufficient substrate in the tank may restrict your crab's ability to molt properly, often leading them to resort to surface molting due to lack of space.
Incorrect Substrate Mixture - Australian crabs require a ratio of 8 parts play sand to 1 part damp coir peat in order to establish a secure and adequately moist substrate conducive to molting. It is imperative to avoid using unsuitable substrates such as plain sand, plain coir peat, reptile bedding, dirt, pebbles, rocks, or tanbark. Should these substrates be utilized in the tank, the crab will be compelled to undergo a surface moult.
Stress - When hermit crabs are removed from their natural habitat and transferred to pet stores, they experience significant stress. This stress is exacerbated by the unsuitable conditions typically found in pet store tanks. It is not uncommon for hermit crabs to undergo surface molting while in pet store tanks, and they may continue to be in a state of stress even after being taken home, leading to subsequent surface molts. Inadequate housing conditions, such as excessive handling, lack of privacy, overcrowding, and unsuitable environments, can induce enough stress to trigger surface molting in your hermit crabs.
How can you tell the difference between a surface moult or a dead crab?
It can often present a challenge to distinguish between a deceased hermit crab and a surface moult, as their appearances bear striking similarities.
When a crab undergoes molting, it may exhibit minimal movement and appear lifeless, partially hanging out of its shell. In the event of a crab's death, it will be found dangling out of its shell in a manner similar to molting. However, a deceased crab may emit a fishy odor and often detach from its shell when handled, serving as a definitive sign of its demise.
If there is any uncertainty, observing the crab closely for an extended period can help differentiate between molting and death. Any slight twitches or movements observed indicate that the crab is surface molting.
Follow the below steps if you find a surface moulting hermit crab.
Establish an isolation tank or container promptly for the molting crab, equipped with a shallow layer of moist substrate.
Handle the moulting crab delicately using a spoon, ensuring not to make direct contact with them (by scooping up the sand beneath them with the spoon during the lifting process). Transfer them carefully into the isolation container, which should remain free of any other contents.
Reinsert the isolation tub into the main tank and ensure it is covered to maintain darkness, providing privacy for your crab (a cloth or towel can be used for this purpose).
Should you come across a crab in the midst of molting, and it has shed its exoskeleton, please refrain from discarding it. Instead, place the exoskeleton in the isolation tub with the molting crab for consumption. It is crucial for them to ingest their previous exoskeleton in order to facilitate the restoration of their strength and to acquire the essential calcium required for the hardening of their new exoskeleton.
It is recommended to isolate your surface moulting hermit crab during the moulting process. After consuming their exoskeleton and once their new exoskeleton has hardened, allowing them to move around and eat/drink comfortably, they can be reintroduced into the tank with the other inhabitants.
FAQ on surface moulting -
Why is surface moulting so dangerous? During the moulting process, hermit crabs shed their rigid outer exoskeleton, rendering them with a soft and susceptible exoskeleton. Consequently, this heightened vulnerability makes them prime targets for consumption by other hermit crabs.
Should I add food and water to the isolation tub? It is recommended to add this after the crab has completed its moult and is actively moving around.
When should I move my crab back into the main tank with the rest of my crabs? Your crab is prepared for relocation from isolation once it has largely shed its old exoskeleton, the new exoskeleton has solidified, and the crab is actively moving around with assurance.
What do I use for an isolation tub?
One highly effective option is to utilize an isolation tub, which consists of small, transparent plastic containers equipped with a secure lid and air flow apertures.
If an isolation tub is not readily available, a Tupperware container can be used as an alternative by creating airflow holes in it.
What if I am still not sure if my crab is surface moulting or dead? Unfortunately, numerous surface moulting crabs have been mistakenly discarded by their caretakers due to the misconception that they were deceased. When uncertain, it is advisable to consider the possibility of a surface moult. Over time, it will become apparent if the moulting process is not advancing, particularly if the crab emits an odor.
*A Hermit Crab surface moulting in an isolation tub.
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