Why Did My Hermit Crab Die?

Hermit crabs may perish for various reasons. Occasionally, this is due to the environment we provide or errors we have made, while at other times, it may be entirely beyond our control.

What Is the Lifespan of Hermit Crabs?

In their natural habitat, hermit crabs can live for over 40 years. When kept in captivity, they have the potential to live for more than 15 years. Therefore, if a hermit crab's lifespan is only a few months or a year in captivity, it indicates that there may be underlying issues.

How to Determine if Your Hermit Crab is Deceased

For beginners, it can be challenging to distinguish between a deceased hermit crab and one that is surface molting.

A significant indicator of a deceased crab is a fishy odor emanating from it.

However, this process may not occur immediately. Below are some common indicators that a crab has deceased:

• Upon lifting the crab, it falls out of its shell, indicating it can no longer maintain its grip due to death.

• The exoskeleton remains intact, and the crab exhibits no signs of movement.

• The eyes appear glazed over, displaying a grey or whitish hue.

• There is a complete absence of movement from the crab.

• The crab's body is outside of its shell, showing no signs of life.

• When in the pool, the crab is entirely lifeless and limp upon being picked up.

Indicators of a Surface Moult Versus a Deceased Crab

Occasionally, crabs may undergo moulting on the surface due to stress or unsuitable conditions. During this process, they may resemble a deceased crab, when in reality, they are experiencing a delicate surface moult.

Indicators of a surface moult include:

• The crab appears lifeless and is lying on its side.

• The crab has partially emerged from its shell.

• The exoskeleton has started to detach from the crab.

• Upon close observation, slight movements, such as jerks and twitches, can be seen in the moulting crab.

• An empty exoskeleton is found on the substrate.

• When handled, the crab continues to hold onto its shell.

Surface moulting poses significant risks, necessitating immediate isolation of the crab.

If you are uncertain whether your crab is deceased or undergoing surface moulting, isolate it as a precaution. Over time, it will become evident whether the crab is alive. If the exoskeleton is shed and a crab remains inside the shell after a few weeks, the crab is alive and undergoing surface moulting.

If, after a few weeks, there is no change and the crab begins to emit an odor or is covered in mold, it has unfortunately passed away.

For further information on surface moulting, please visit our Surface Moulting Blog here.

https://www.happyhermie.com.au/post/surface-moulting-a-hermit-crab-emergency

What Are the Causes of Death in Hermit Crabs?

There are several factors that might have led to the death of your hermit crab. We will discuss each of these below.

• Unsuitable Tank Conditions

Unsuitable tank conditions significantly contribute to the mortality of crabs. Factors such as inadequate heat and humidity, improper and insufficient substrate, and lack of deep pools place considerable stress on crabs, potentially leading to their demise. Fortunately, these issues are easily rectifiable, making it entirely preventable for a crab to perish due to tank conditions.

• Naked Crab

In the event that a hermit crab abandons its shell, it constitutes an emergency situation that requires immediate attention. The crab should be isolated with a selection of suitable shells. Unfortunately, if the crab does not adopt a new shell, it will not survive, as lacking a shell is fatal. The shell is essential for protecting and maintaining the moisture of their soft abdomen. Ensure there is an adequate supply of suitable shells available to prevent this situation. Additionally, hermit crabs may abandon their shells due to extreme stress or unsuitable tank conditions.

• Attacked by Another Crab

It is unusual for crabs to attack and kill one another. Typically, they are not predators but rather prey animals and scavengers. They consume what they find rather than actively hunting for food.

Hermit crabs require a daily diet consisting of at least 50% protein. Insufficient protein in their diet may lead them to extreme measures to compensate for this deficiency, potentially resulting in aggressive behavior towards their tank mates. If you observe that your crabs are consistently harming each other, consider increasing their protein intake.

• Drowning

Hermit crabs are at risk of drowning if they do not have a safe means of entering and exiting their pools. While they are capable of determining when to enter and leave the water, the absence of a secure exit can lead to drowning. This situation often arises when deep pools are provided without adequate exit solutions. Ladders may become dislodged and fall into the pool or rise above the water level, preventing the crab from exiting safely. Regular monitoring of the pools and their ladders is crucial to prevent such incidents.

Do not let this discourage you from providing deep pools, as they are essential for crabs to fill their shell water.

There is no specific time limit for how long a crab can remain submerged. Some crabs have been observed spending several hours in their pools before emerging.

• Stress

Stress significantly impacts the health of hermit crabs. Prolonged and excessive stress can lead to their demise. Stressful conditions include overcrowding, frequent handling, removing them from their tank for play, disturbing them by digging, unsuitable tank conditions, frequent relocation (from one tank or place to another), accidental dropping, inadequate heat, and low humidity levels.

• New Crab Syndrome

This term refers to the experience of acquiring a new hermit crab from a pet store. These crabs endure significant stress, having been captured from the wild, subjected to harsh conditions, forced into painted shells, transported to the store, and often housed in unsuitable tank environments before being purchased and brought to a new home. Such conditions can be overwhelming for the crabs.

Some crabs recover from this stress with a period of adjustment and moulting beneath the substrate. However, some may not survive the ordeal. Unfortunately, when purchasing crabs from pet stores, there is no assurance of their survival. Even with the best care and environment provided, the outcome ultimately depends on the crab's resilience, and there is little more that can be done.

• Excavating Hermit Crabs

Excavating hermit crabs poses significant risks. This practice not only induces considerable stress but can also be fatal if the crabs are in the midst of moulting. During this period, crabs are exceptionally fragile and must not be disturbed. Interfering with them during moulting can lead to limb loss, unsuccessful moulting, and ultimately, death.

• Sickness

We cannot ensure the health of our crabs when they are captured from the wild, as they may arrive already ill or weakened. Unfortunately, in such cases, there is no intervention possible, and they may eventually perish. Additionally, crabs can develop a condition known as shell rot, characterized by a dark brown or black rot on their limbs. This condition is highly contagious and can be fatal. However, if detected early, it is treatable. Shell rot is typically caused by feeding crabs raw shellfish; therefore, all shellfish should be cooked before being offered as food.

• Disturbance During Moulting

It is crucial to avoid disturbing a crab during its moulting phase, and other crabs should also refrain from interfering. During this period, the crab's exoskeleton is extremely soft and delicate. Additionally, the crab emits a scent that may attract nearby crabs, potentially leading them to view it as an opportunity for a subterranean meal.

This issue often arises in overcrowded tanks, where the substrate is insufficiently deep or the tank is too small. Therefore, it is advisable to provide at least 38 liters of space per crab in the tank.

• Inappropriate Diet

The diet of hermit crabs is crucial for their well-being. They require a balanced intake of protein, calcium, vitamins and minerals, fibre, beta-carotenes, carbohydrates, healthy fats, anthocyanins, tannins, and supplements.

Neglecting to provide a proper and balanced diet can lead to a severely weakened and nutrient-deficient crab, ultimately resulting in its death. An inadequate diet can cause additional problems such as unsuccessful moulting, cannibalism, lethargy, stunted growth, and mortality. It is essential to avoid feeding your crabs commercial pet store foods or pellets, as these do not meet their dietary needs.

Ensure that you offer fresh foods and high-quality dried mixes, along with supplements like greensand, worm castings, and insect frass.

• Emerging Prematurely from Moulting

Typically, hermit crabs undergo moulting beneath the substrate, consume their exoskeleton, allow their new exoskeleton to harden, and then emerge. This process constitutes a successful moult. However, some crabs may emerge prematurely, before their exoskeleton has fully hardened. Emerging with a soft exoskeleton and the scent of a fresh moult can attract other crabs. Due to their vulnerability, these crabs are susceptible to attacks, injuries, or even being killed and consumed by others. If a soft crab is discovered, it should be isolated immediately until its exoskeleton has hardened before rejoining the main group.

• Unsuccessful Moulting

An unsuccessful moult occurs when a hermit crab does not survive the moulting process. This may be due to weakness, inadequate diet, existing illness, or excessive stress. Indicators of this situation include the crab burrowing to moult, after which it is not seen again. If you need to excavate the substrate and discover an empty shell, it indicates the crab has deceased and decomposed.

• Shell Jacking

Shell jacking occurs when one hermit crab attempts to seize the shell occupied by another hermit crab. The aggressor will try to coax the other crab out, using its large claw to grasp one of the victim's legs or claws in an effort to forcibly remove it from its shell. Hermit crabs are known to prefer being torn apart rather than relinquishing their cherished shell. This often results in the death of one crab, as it may be torn in half during the struggle.

• They have ingested a toxic substance

It is crucial to be knowledgeable about safe and unsafe foods, plants, and wood before introducing any items into your tank. If your hermit crab ingests a toxin, there is a significant risk of fatality. This also applies to the use of toxic materials near the tank, such as essential oils, insect sprays, diffusers, and chemicals.

For further information on safe and unsafe foods, plants, and wood, please refer to this resource.

https://www.happyhermie.com.au/post/hermit-crabs-safe-and-unsafe-foods

It is common for owners to occasionally lose a crab, particularly if they frequently purchase them from pet stores. However, if you experience consistent losses over a short period, such as your entire group within a year, or if every crab you acquire from a pet store dies, and they only survive for an average of a few months to a year, the problem likely lies with your care. It is essential to thoroughly evaluate your tank conditions and the provisions you are offering. Is your tank maintained at the appropriate temperature and humidity? Do you have the correct substrate ratio at the proper depth? Is your tank overcrowded? Are there enough shells available in the correct sizes? Are you providing a varied and balanced diet? Are you handling them excessively?

It is essential to address these issues before proceeding with the purchase of additional crabs to replace those that have died.