Hermit Crab Behaviour

It is fascinating to note that every hermit crab possesses a unique personality. Some may exhibit shyness, while others are more outgoing, and there are those that prefer solitude. These crustaceans are observed to display a variety of behaviors and personalities, whether in their natural habitat or under captivity.

In the following section, we will delve into the nature of these behaviors and their significance.

Shyness and Hiding Some captive hermit crabs exhibit timid behavior, choosing to remain hidden when humans are near their tank and venturing out at night for feeding and other activities. They may spend extended periods in seclusion and scurry away swiftly when approached.

This behavior is considered normal, particularly in newly captive crabs. Referred to as Post Purchase Syndrome (PPS), it occurs when a hermit crab is transitioned from a pet store to its new tank, experiencing significant stress that often leads to burrowing into the substrate or seeking refuge in hiding spots to alleviate stress. It is crucial not to compel a timid or reclusive crab to engage in social activities. Providing hiding spots is essential to ensure that they feel safe and secure.

Digging Hermit crabs engage in digging behavior for various reasons beyond moulting. This includes seeking solace upon introduction to a new tank, engaging in recreational activities, scouting ideal locations for moulting, and creating a refuge from unfavorable conditions like excessive heat, cold, or dryness.

Nevertheless, excessive digging is a common behavior and not a cause for concern.

Climbing Land hermit crabs possess remarkable climbing abilities and derive pleasure from engaging in climbing activities. Therefore, it is imperative to ensure that the tank is equipped with a secure lid, as these crabs are capable of escaping if provided with the opportunity. In their natural habitat, hermit crabs frequently ascend trees and other elevated structures to seek refuge from ground predators, often choosing elevated spots for resting. To cater to this natural behavior, it is advisable to provide captive crabs with climbing objects to promote physical activity and mental stimulation.

Flicking/Pushing

It is common to observe instances where crabs exhibit behaviors such as flicking or pushing each other when they are in close proximity. These actions typically serve as a means of communication, with one crab signaling to the other to maintain a distance or give them space. Larger crabs often use flicking as a way to assert their dominance over smaller crabs in their vicinity.

This behavior may indicate a display of dominance or irritation. It is advisable to monitor the situation closely, as it could escalate into a more confrontational dispute, necessitating your intervention.

Antennae Fights One fascinating behavior to observe is the interaction between two hermit crabs as they approach each other and gently brush or wiggle their antennae against one another. This action may seem rapid and potentially aggressive, but as long as there is no harm being done, it is advisable to allow them to engage in this interaction to enhance their social skills.

Shell Aggression (known as Shell Jacking) Occasionally, crabs may encounter a shell that appeals to them; however, it may already be occupied by another crab. In such cases, the crab interested in the shell may attempt to appropriate it from its current occupant. This behavior is referred to as shell jacking, and while it is not uncommon, it should be regarded seriously.

When a hermit crab desires a new shell, it will approach the current shell's owner and gently tap its own shell against the other crab's, prompting the crab to investigate. Subsequently, the hermit crab, known as the "shell jacker," may attempt to coax the other crab out of its shell by delicately grasping a leg or claw. In some cases, the crab being targeted may willingly shed a limb or walking leg to safeguard its shell, prioritizing shell protection over physical integrity.

Efforts to forcibly remove a hermit crab from its shell typically result in limb loss or severe injury. These creatures possess remarkable abdominal strength to secure their shells and are unlikely to relinquish their homes under duress.

The most common cause for this can be due to a lack of available shells in the tank for each Hermit Crab. If you happen to come across a shell jacking in progress, it is important to remove the shell jacker from the situation. You can isolate them for a small period of time with some other suitable shells, perhaps similar to the one that they have tried to steal (both style and opening)

Chirping or Croaking (also known as Stridulation) Hermit Crabs are naturally known as quiet pets, however, sometimes they will make a chirping or croaking sound. This can often be heard if the crab is feeling fearful, in an aggressive situation, discomfort or annoyance. If you do happen to hear chirping coming from your tank, it is best to check it out right away to investigate the cause.

Mating Contrary to belief, Hermit Crabs can and do mate in captivity. Although not common, it does happen. During mating season (summer) Male Hermit Crabs will seek out females to mate with, although the males are keen to mate, it is entirely up to the female if mating will go ahead. She will release a pheromone that announces she is ready to mate, the male will detect this pheromone and approach the female. Males will often fight over who gets to mate with the female, but only she will decide who will be successful in doing so. Mating may appear aggressive, and like the male is trying to remove the female from the shell, Hermit Crabs mate while still wearing their shells to ensure their safety. The male will approach the female and tap, stroke or rock her shell back and forth to encourage her to come out. The male and female will partially come out of their shells and hold each other face to face like a hug; the male will then deposit his sperm into the females gonopores, if fertilized, the female will carry her eggs around until she is ready to drop them into the ocean to spawn.

Shell Alterations Perhaps you have noticed your crab munching on their own shell, or maybe ever so slowly, parts of their shell appear to be disappearing. Hermit Crabs will pick a shell that they like and will often alter it to fit the way they prefer. They will use their claws to pick part of their shell off to make it a more suitable and comfortable fit. This is completely normal and safe behaviour. The only time this behavior is dangerous, is if your crab is wearing a painted shell, during alteration, they may accidently pick off toxic paint and consume it. This is why it is so important to only ever supply natural shells within your tank.

Shell Shopping Just like when you go clothes shopping and try on everything, so do Hermit Crabs! They can be quite picky when trying to find that perfect shell and will often spend hours or days trying on various shells until they find one that they like. This behaviour is normal and not something to be concerned about if you have a large variety of shells on offer in the correct sizes. Eventually your crab will find the perfect shell and will stick with it.

Excessive Exercise Perhaps you have an exercise wheel in your tank, and you have noticed your crab spending hours at a time going around and around. This is because in the wild, Hermit Crabs travel many kilometers a day going from one place to another. It may appear as excessive exercise to you, but to them, it's just another daily journey travelled. Captive crabs often enjoy having a wheel in their tank to keep them busy walking and entertained for hours on end.

Swimming or Bathing Hermit Crabs require deep pools of water so they can fully submerge their shells, this helps them to fill their shells with water to keep their abdomen from drying out. They will also need a deep-water source to drink and bathe themselves. Hermit Crabs will often clean out sand, poo and other debris from their shells while in their pools. Some crabs are toe dippers, and you may never see them fully submerge, and some crabs are obsessive swimmers and will spend hours at the bottom of their pools. As long as you have supplied a safe way in and out of the pools, they can spend as long as they like in the water and will resurface when they are ready.

Shell Dropping A very serious behaviour that should not be taken lightly. Hermit Crabs should never be without their shells, so if they are dropping their shell and making nudie runs around the tank, it's time to take action! Possible causes for shell dropping include, shell jacking victim, not enough appropriate shells on offer, stress, fear, sickness or an unsuitable tank environment. You can read more about naked Hermit Crabs and what to do here https://www.happyhermie.com.au/post/naked-hermit-crab-what-to-do

*Hermit Crab pictured belongs to The Happy Hermie