Common Hermit Crab Myths

We aim to clarify some of the most prevalent myths concerning hermit crabs within the community. You may have encountered these topics online or perhaps even accepted them as true. Our goal is to dispel these misconceptions and provide you with accurate information about hermit crabs.

MYTH - It is not feasible to breed hermit crabs in captivity

FACT - This is a widely circulated myth within the global hermit crab community: the belief that breeding hermit crabs in captivity is impossible without scientific expertise or laboratory facilities. However, this is not the case. Numerous home breeders worldwide, including multiple in Australia, have successfully bred hermit crabs in their own tanks without the need for a laboratory or a science degree. While it is undoubtedly challenging, it is entirely achievable.

MYTH - Hermit crabs possess a relatively brief lifespan, typically lasting only a few years.

FACT - This is incorrect. In their natural habitat, hermit crabs can live up to 40 years. In captivity, their lifespan can reach up to 15 years, and sometimes even longer. The misconception about their lifespan arises from the fact that many crabs are kept in unsuitable environments or are mishandled, leading to their demise within a year of purchase. Common causes of premature death include stress, surface molting, aggression, shell theft, drowning, and inappropriate conditions with inadequate heat and humidity. With proper care, hermit crabs can actually enjoy a long lifespan.

MYTH - Moulting above ground is a normal occurrence

FACT - A surface moult is considered highly unnatural for a hermit crab. It is not a voluntary action, but rather a response to unsuitable conditions in their environment.

Moulting above the surface is hazardous for crabs, as this phase is critical, and they are particularly vulnerable. During a surface moult, they are exposed to predators and other hermit crabs. After shedding their exoskeleton, the new, soft exoskeleton is highly prone to attacks. Surface moulting often occurs due to inadequate substrate that prevents safe digging and moulting. This issue is prevalent in pet stores and small tanks using shell grit, tanbark, rocks, etc., as substrate. If a crab is observed surface moulting, it should be isolated immediately to safely complete the process.

MYTH - Hermit crabs are capable of thriving in diverse environments

FACT - This statement is inaccurate. In their natural habitat, hermit crabs inhabit hot and humid tropical environments. When they are relocated to pet stores, they are often sent to colder regions of Australia, far removed from their natural settings. Hermit crabs are not found in the wild in colder areas of Australia, such as Victoria or Tasmania, as they cannot survive in such climates. Therefore, it is crucial to replicate their natural environment within their tank to ensure their survival and well-being.

MYTH - Hermit crabs can bite

FACT - Hermit crabs lack teeth, so they cannot bite. However, they are capable of pinching, and they can pinch quite strongly. When handling your hermit crab—ideally only for welfare checks, shell sizing, emergencies, or determining sex—ensure you hold them by their shell and keep your hands away from their pincher claws. If a hermit crab pinches you, it may grip tightly and refuse to release. Do not shake your hands, as this could cause the crab to fall from a significant height. Instead, immerse your hand (and the crab) in water to encourage it to release, or run lukewarm water over it until it lets go. If these methods are ineffective, some have resorted to using tweezers to gently pry open the large claw. Nonetheless, it is advisable to avoid handling them unless absolutely necessary.

MYTH - Hermit crabs are at risk of drowning in deep water pools

FACT - Hermit crabs are at risk of drowning; however, providing a secure and stable entry and exit for your pools can prevent this. They require deep pools of water to fully submerge and replenish the water in their shells as necessary.

MYTH - They appreciate interaction with their owners

FACT - Your hermit crab is a creature originating from the wild and is considered a prey animal, making it a target for predators.

Interaction with humans can be highly stressful and unnatural for these animals, regardless of how long they have been in your care. They do not perceive you as a parent figure; instead, they view you as a potential threat. Nevertheless, you can form a connection with your pets by observing them from behind the glass, allowing them to flourish and enjoy their habitat safely.

MYTH - Movement around the exterior of the tank indicates a content and energetic crab

FACT - Unfortunately, no. If you remove your crab from the tank and place it on the ground, couch, bed, table, etc., and it begins to move around quickly, this behavior indicates fear as it desperately seeks a safe place to hide. The predator/prey instinct is activated once more. Additionally, they will struggle to breathe in the low-humidity environment outside of their tank. Imagine if someone reduced your oxygen supply, leaving you with just enough to survive but causing you to struggle with every breath. This is what occurs when your crab is placed in low-humidity environments. Hermit crabs breathe by absorbing oxygen in humidity through their modified gills.

MYTH - They express affection by nuzzling into your clothing, neck, or hair.

FACT - Once more, considering the predator/prey dynamic, these creatures seek a secure environment to shield themselves from potential threats. Hermit crabs are unable to experience human emotions or form connections akin to those of dogs or cats. However, this does not imply that they lack feelings. They experience fear, safety, comfort, happiness, loneliness, hunger, thirst, and pain, but they do not feel love for another being.

MYTH - They consistently change shells either prior to or following a moult

FACT - It is unpredictable when a crab will change its shell. This process can occur multiple times a day, annually, or even after several years. Occasionally, hermit crabs may transition into a shell that is too large prior to moulting, then switch again upon resurfacing. However, this behavior is neither common nor to be anticipated. Therefore, as long as you provide a diverse selection of appropriately sized shells, the decision rests with the crab.

MYTH - They exit their shells to undergo moulting

FACT - Moulting is an exceptionally delicate period for hermit crabs, requiring them to safeguard themselves throughout the process. During moulting, they remain within their shell, slightly extending their body to shed their old exoskeleton. Once the shedding is complete, they retreat back into the shell to recuperate and allow their new exoskeleton to harden. Additionally, they consume their shed exoskeleton to absorb calcium. If a hermit crab leaves its shell to moult, it is a highly dangerous situation and a cause for concern.

MYTH - Hermit crabs require fresh air for respiration

FACT - Hermit crabs lack lungs and instead possess modified gills that extract oxygen from moisture in the environment. Consequently, they require elevated humidity levels for survival. It is unnecessary to provide air vents or breathing holes in their enclosure, as they do not require fresh air. They will not experience suffocation if the humidity is adequately maintained in a sealed tank.

MYTH - They require minimal living space

FACT - It may be surprising, but each crab requires a minimum of 38 litres of space. Consequently, to accommodate two crabs, a tank with at least 76 litres is necessary. This ensures that each crab has a sufficient amount of substrate to moult safely without the risk of being discovered and attacked by other crabs. Overcrowding a tank can result in aggression, shell theft, stress, and other issues.

MYTH - Painted shells can be cleaned and reused

FACT - While it would be beneficial if this were true, the reality is that painted shells are harmful to hermit crabs due to their toxicity. Many may not realize that even attempting to remove the paint does not eliminate the risk, as toxins have already permeated the shell, rendering it unsafe and unusable. The recommended approach is to discard painted shells and provide only new or naturally collected shells from the beach.

MYTH - They are affordable and low-maintenance pets

FACT - Many misconceptions exist, and we've all encountered them. The reality is that setting up your tank can be quite costly, often requiring at least several hundred dollars. Additionally, ongoing expenses such as salts, food, shells, water conditioners, electricity, water, and supplements contribute to the overall cost. Contrary to popular belief, maintaining these pets is not inexpensive. While they can be manageable if cared for properly, they are not suitable as a young child's first pet or sole responsibility. Regular water changes, feeding, and monitoring is essential. Unlike a house cat, which requires only feeding and litter box maintenance, caring for hermit crabs involves significant attention. They are not pets you can neglect for extended periods. However, with time and dedication, they can be easy, interesting, and enjoyable pets, though adult supervision is necessary.

MYTH - It is advisable not to house large and small crabs together

FACT - In the wild, large and small crabs coexist harmoniously. It is indeed possible to keep hermit crabs of different sizes together. In my own tank, the largest crab is about the size of a tennis ball, while the smallest is comparable to a 10-cent piece. Do they coexist peacefully? Absolutely. Do the larger crabs occasionally flick the smaller ones when annoyed? Certainly. This behavior is quite normal. Hermit crabs establish dominance within the tank through antennae interactions and flicking. They do not engage in size-based conflicts. Aggression typically arises from a lack of suitable shells, overcrowding, stress, or disputes over breeding with females.

Therefore, it is entirely feasible to house crabs of various sizes together.

MYTH - Housing males and females together will result in breeding.

FACT - It is certainly uncommon, though entirely possible, for hermit crabs to breed in captivity. While all males may show interest in females, it is ultimately the female who decides if and with whom she will mate. For breeding to even be considered, both males and females must be completely content, stress-free, happy, healthy, and thriving in optimal tank conditions. Even if breeding occurs, you must persuade the pregnant female that your saltwater pool is equivalent to the ocean, encouraging her to deposit her eggs there for spawning. Breeding hermit crabs in captivity involves numerous complexities, unlike cats or dogs that enter heat and mate readily. Therefore, housing both sexes together is certainly feasible.

MYTH - Similar to their natural beach environment, they require shell grit or crushed shells in their substrate.

FACT - Many of us have observed small shells scattered along the beach. However, while this may be a common sight, hermit crabs do not choose this sandy area for digging and molting. They prefer to move to higher sand dunes, where they dig deep into the sand to moult. Therefore, we recommend a substrate similar to their natural moulting environment, such as a mix of sand and damp coir peat. Crushed shells are unnecessary for their tank substrate and provide no beneficial purpose.

MYTH - They are unable to climb or escape

FACT - Indeed, they are capable and will do so if provided the opportunity. Hermit crabs are exceptional climbers and can ascend nearly any surface, including the silicone in the corners of your tank. In their natural habitat, they frequently climb high into trees to rest, thereby avoiding ground predators. This underscores the importance of ensuring that your tank is completely sealed. Any gap or an uncovered lid for prolonged periods will be discovered by them.

MYTH - Their diet consists exclusively of fruits and vegetables.

FACT - Hermit crabs require a diverse and balanced diet to ensure their survival and well-being. While fruits and vegetables are essential, their diet must also include protein, calcium, fibre, carbohydrates, fats, leaf litter, and aquatic plant matter.

Protein should constitute at least 50% of their daily intake, and calcium supplements should be readily available at all times. Protein sources include animal meats, nuts and seeds, insects, and eggs. Calcium can be sourced from eggshells, starfish, cuttlefish bone, sea urchins, and sand dollars.

MYTH - Being without a shell is considered normal

FACT - It is not typical for a crab to be without its shell; a shell-less crab is at significant risk unless it acquires a new shell promptly. Crabs may abandon their shells due to stress, shell theft, or unsuitable environments. If you encounter a shell-less crab, it should be isolated with available spare shells and a small amount of optimal water, remaining there until it occupies a new shell.

MYTH - Crabs available at pet stores have been selectively bred for life in captivity

FACT - Unfortunately, all hermit crabs available in pet stores are sourced from their natural habitats and distributed to pet stores across Australia. The crabs currently in your tank were taken from the wild prior to reaching you.

MYTH - It is allowable to dig up your crabs

FACT - It is imperative to avoid disturbing hermit crabs by digging them up, as this can induce significant stress and, if they are molting, may lead to fatal consequences, limb loss, or other complications. Digging up a crab is permissible only in emergency situations, such as tank flooding, ant infestations, or natural disasters like bushfires, hurricanes, floods, or tornadoes, when evacuation of your home is necessary.

MYTH - They are unable to change genders

FACT - Contrary to common belief, hermit crabs have the ability to change genders from male to female and vice versa. This transformation can occur during a moult. While not a frequent occurrence, it is documented. The underlying reasons for this phenomenon remain unclear.

MYTH - It is essential to routinely clean and replace the tank substrate.

FACT - By establishing your tank substrate with the appropriate ratio and consistency from the outset, there will be no necessity for replacement. Replacement is only required if the substrate becomes completely dry, if there is a tank flood, or in the event of an ant infestation. You can maintain the surface by removing buried shells, scattered or mouldy food, leaf litter, and waste.

MYTH - Pet store foods and pellets meet their nutritional requirements

FACT - Regrettably, pet store foods contain only a limited range of ingredients and insufficient quantities to meet the comprehensive nutritional requirements of protein, calcium, carbohydrates, fibre, fats, carotenoids, aquatic plant matter, and supplements. These foods often include additives for extended shelf life, which may not be safe for hermit crabs. Furthermore, pellets are highly unnatural and not something they would encounter or consume in their natural habitat. It is advisable to provide them with fresh foods from your pantry and refrigerator, as well as dried, all-natural foods from a reputable hermit crab food supplier.

MYTY - They are capable of living alone

FACT - In their natural habitat, they reside in large colonies. When kept in isolation, they can experience loneliness. Although referred to as hermits, they are highly social creatures and thrive when housed with companions.

MYTH - The presence of hairy legs can indicate the gender of your hermit crab

FACT - This is a common misconception. All hermit crabs exhibit hairy legs following a fresh molt. It is often stated that a hermit crab with hairy legs is male, but this is inaccurate. The only method to accurately determine the gender of your hermit crabs is to examine the underside of their third set of walking legs. If you observe two small dots (gonopores), the crab is female; if these are absent, the crab is male.