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Common Hermit Crab Myths

Updated: Nov 18, 2023

Let's break open some of the biggest Hermit Crab related myths spread around the Hermit Crab community! I'm sure you've heard or read some of these topics online, maybe you have even believed them. Well we are hear to bust these myths and tell you the true facts related to Hermit Crabs.


• Breeding Hermit Crabs in captivity is impossible

This is probably one of the most commonly spread myths across the world within the hermit crab community. That it is impossible to breed Hermit Crabs in captivity without being a scientist or having a lab. But that's just not true. There are many at home Breeders across the world, 3 of those being in Australia. All who have successfully bred Hermit Crabs within their very own tanks at home, with no lab or science degree. It's certainly not easy, but it is definitely doable!


Hermit Crabs have a short lifespan of only a few years

Nope, not true. In the wild, Hermit Crabs can live for upto 40 years! In captivity they can live for upto 15, but sometimes even longer. The reason this myth is so widely believed is because so many crabs are placed into inappropriate setups or are mishandled and pass away within a year of purchase. Common reasons for them passing away so soon can be caused by stress, surface moulting, aggression, shell jackings, drowning, inappropriate setups with low heat and humidity. If treated right, they actually have a very long lifespan.


Moulting above ground is normal

A surface moult (as we call it) is one of the most unnatural things for a Hermit Crab. Not only is it not natural, it is never something they will choose to do, often being forced to do so because of the conditions that they have been placed into.

It is never safe for a crab to moult above the surface, this is a very critical time in their life and they are extremely delicate during this process. Moulting above the surface puts them on full display to predators and other Hermit Crabs. Once they shed their exoskeleton, their new soft exoskeleton is extremely susceptible to attacks. Usual reasons for a hermit crab to surface moult is due to a lack of appropraite substrate to safely dig and moult. This is very common in pet stores and small tanks with shell grit, tanbark, rocks etc as the substrate. If you find your crab surface moulting, it must be isolated immediately to complete its moult.


Hermit Crabs can thrive in any environment

Not true. In the wild, Hermit Crabs only live in hot and humid tropical environments. When they are removed from these environments and sent to pet stores, they are being sent to cold parts of Australia that are no where near close to their natural environment. You wont find Hermit Crabs in the wild in cold parts of Australia such as Victoria or Tasmania as they cannot survive there. This is why it is so important to create their natural environment within their tank so that they can survive and thrive.


Hermit Crabs bite

They don't actually have teeth, so how can they? What they can do though, is pinch! And boy can they pinch! If you are handling your Hermit Crab (preferably only for welfare checks, shell sizing, emergencies, sexing) make sure to only hold them by their shell and keep your hands away from their pincher claws. If a hermit crab pinches you, they can sometimes get a death grip on you where they simply will not let go! You must not shake your hands around as this can cause your crab to fall from a great height. Instead, either dunk your hand (and crab) into the pool to get him to release or run him under lukewarm water until he releases. If all else fails, there have been cases of people using tweezers to try and pry the large claw open. But we think it's just best not to handle them to begin with, unless it is absolutely nessessary.


Hermit Crabs will drown in deep pools of water

Hermit Crabs can drown yes, BUT they will not drown if you supply a safe and sturdy entry and exit to your pools. They need deep pools of water so that they can fully submerge and fill their shell water when needed.


They enjoy being handled by their owners

Your Hermit Crab is a wild animal. It came from the wild. It is also a prey animal, meaning they are targets for predators.

Being handled by humans is extremely stressful and unnatural for them, no matter how long you have owned them. They don't see you as their Mum or Dad, they only see a predator who may hurt them. You can still bond with your babies from behind the glass and nothing is better than watching them thrive and enjoy their crabitat from behind the safety of the glass.


Running around outside the tank is a sign of a happy and active crab

Sadly, no. If you remove your crab from the tank and place them on the ground, couch, bed, table etc and they start scuttling around quickly, this is because they are frightened and desperately trying to find a safe place to hide. The Predator/Prey comes back into play yet again. They will also find it hard to breathe in the low humid environment outside of their tank. Imagine someone takes away most of your oxygen, leaving you with just a small amount so that you are still alive but you are struggling with every breath to actually breathe. That's what happens when your crab is placed into low humidity environments. Hermit Crabs breathe by aborbing oxygen in humidity through their modified gills.


They show affection by burying into your clothes, neck or hair.

Again, the predator/prey. They are simply looking for a safe space to hide from any potential threats. Hermit Crabs are incapable of feeling human emotions or creating human connections like that of a dog or cat. But that doesnt mean that they dont still feel. They feel scared, safe, comfortable, happy, lonely, hungry, thirsty, pain etc. But they don't feel love for another being.


• They always change shells before or after a moult

There is no telling when a crab will change their shell. Sometimes they change their shells multiple times a day, sometimes once a year and sometimes it takes years for them to change. Sometimes Hermit Crabs may change into a shell that is too big before going down to moult and then changing again when they come back up. But this is not something that is commonly done or is to be expected. So as long as you have a great selection of shells in the right sizes on offer, the rest is upto your crab.


They leave their shells to moult

Never. Moulting is an extremely delicate time, and the Hermit Crab must protect themselves while doing so. They will always stay within their shell during a moult, bringing their body out slightly and shedding their old exoskeleton. After they have shed, they will retreat back into the shell to recover and let their new exoskeleton harden. They will also spend this time consuming their shed exoskeleton to gain calcium. If your crab is leaving their shell to moult, this is extremely dangerous and not a good sign at all.


Hermit Crabs need fresh air to breathe

They dont have lungs, instead they have modified gills that absorb oxygen through humidity. This is why they need high levels of humidity to survive. There is no need to create air vents or breathing holes in your tank as they dont breathe fresh air. They will not suffocate if they have high humidity in a sealed tank.


They dont need much space to live

This might shock you, but each crab needs atleast 38L of space. That means to house 2 Crabs, you need a 76L tank minimum. This is to ensure that each crab has a safe amount of substrate to safely moult without being discovered and attacked by other crabs. Overcrowding a tank can lead to agression, shell jackings, stress etc.


You can clean and reuse painted shells

If only this one was true. Imagine how much money we could all save! We all know painted shells are toxic to Hermit Crabs. What some may not know is that you can try your heart out to clean the paint off the shells, however, the toxins have already absorbed into the shell making it completely useless and unsafe. It is best practice to just bin the painted shell and only offer brand new or beach collected natural shells.


• They are cheap and easy pets

Oh the lies, we have all been there have we not?! The truth is that setting up your tank can be quite expensive, atleast a few hundred dollars, if not more. And then there is the upkeep of salts, foods, shells, water conditioner, electricity, water, supplements etc. Not so cheap after all I'm afraid. As for easy pets, they can be easy to maintain if you do it right. But they are certainly not a young child's first pet/full responsibility. They need continued water changes, feeding, monitoring etc. Unlike a house cat where you simply feed them and clean their kitty litter. Alot goes into the care of Hermit Crabs. They are not the kind of pet you can just leave for weeks on end and forget about. If you have the time and dedication though, they can be easy, interesting and fun pets to have. But they certainly need adult supervision for keeping.


You should not house big and small crabs together

In the wild, jumbo crabs and tiny crabs live side by side. You can most certainly house various sizes of hermit crabs together.

In my own tank, my largest boy is a tennis ball size and my smallest girl is that of a 10c piece. Do they get along? They sure do! Do my big boys give a little flick to the little ones when they start to annoy them? Heck yes. But that is very normal. Hermit crabs will show dominance within the tank through antennae fights and flicking of crabs below them. Crabs will not fight with each other based on size. Agression usually comes into play due to lack of appropriate shells, overcrowding, stress or arguing over breeding with the females.

So, yes! You can certainly house crabs of various sizes together.


If you house males and females together they will breed

Definitely not. It is not common (but 100% possible) for hermit crabs to breed in captivity. All males will be interested in females, but only the female will decide if and who she will mate with. Both males and females must be completely content, stress free, happy, healthy and absolutely thriving with pristine tank conditions to even consider breeding with each other.

And even if they do breed, you must then convince your pregnant female that your salt pool is infact the ocean and that she should deposit her eggs their for spawning. Alot comes into play for crabs to breed in captivity, unlike cats or dogs who go on heat and will happily and easily mate, the opposite is true for Hermit Crabs. So yes, you can most certainly house both sexes together.


Just like at the beach, they need shell grit or crushed shells in their substrate

We've all been to the beach and seen teeny tiny shells scattered all throughout the sand right? The thing is, although that may be true at the beach. Hermit Crabs will not choose that sand to dig down and moult in. They do not moult right next to the ocean. Instead, they climb up high to the sand dunes and will dig down deep into the sand to moult. This is why we recommend a substrate that is similar to where they would naturally moult (sand and damp coir peat) crushed shells are definitely not needed in their tank substrate and serve no beneficial purpose to your tank.


They cannot climb or escape

Oh they can, and they will if given the chance. Hermit Crabs are actually outstanding climbers and can climb almost anything (including the silicone on the inside corners of your tank)

In the wild they often climb up high into the trees to sleep, staying safe from predators on the ground. This is why it is so important to ensure that your tank is fully sealed. If there is a gap or a lid off for extended periods of time, they will find it.


They only eat fruits and vegetables

Hermit Crabs need a very varied and balanced diet in order to survive and thrive. Yes they do need fruits and vegetables but they also need protein, calcium, fibre, carbohydrates, fats, leaf litter, aquatic plant matter etc.

Protein should make up atleast 50% of their daily diet and calcium and supplements should be available at all times. Protein can be found in animal meats, nuts and seeds, insects, eggs etc.

Calcium can be found in egg shells, star fish, cuttlefish bone, sea urchins, sand dollars etc.


Being naked (shell-less) is normal

Never. It is never normal for a crab to be without their shell. A naked crab is a death sentence if they do not take a shell soon! Crabs will drop their shells due to stress, shell jackings, inappropriate setups etc.

If you come across a naked crab, they must be isolated with spare shells and a small amount of prime water and kept there until they take a new shell.


Pet store crabs have been bred for captivity

Sadly, no. All pet store Hermit Crabs have been taken from their home in the wild and sent to pet stores all over Australia.

The crabs in your tank right now, have been taken from the wild before they came to you.


Digging up your crabs is okay

You should never dig up your Hermit Crabs, this can cause them great stress and if moulting, can ultimately kill them or cause limb loss and other issues.

The only time it is okay to dig up a crab is during an emergency such as tank flooding, ant infestation, or natural disasters such as bushfires, hurricanes, floods, tornadoes etc when you need to evacuate your home.


• They cannot change genders

It is actually the opposite. Hermit Crabs can change genders from male to female and female to male. This can happen during a moult. It is not overly common, but it does happen. We are still not sure what causes them to do this.


You should regularly clean and change out the tank substrate

If you create your tank substrate with the correct ratio and consistency from the beginning, there is no need to change it out. The only time it would need to be changed is if it completely dries out, you have a tank flood or an ant infestation.

You can clean the top of the sub of buried shells, scattered/mouldy food, leaf litter, poo etc.


Pet store foods and pellets cover their nutrional needs

If only! Unfortunately pet store foods only have a small amount of ingredients and not enough to fully cover their nutrional needs of protein, calcium, carbohydrates, fibre, fats, carotenoids, aquatic plant matter and supplements. Often these foods are filled with additives to make them last longer, which are not safe for our crabbies. Pellets are also extremely unnatural and not something they would ever find and eat in the wild. It is best to offer them fresh foods from your pantry and fridge and dried all natural foods from a proper hermit crab food supplier.


They can live alone

In the wild, they live in large colonies. If housed alone they can and do get lonely. Despite being called hermits, they are extremely socialable creatures and prefer to be housed with tank mates.


Hairy legs determine the gender of your Hermit Crab

This is definitley an old wives tale. ALL hermit crabs have hairy legs after a fresh moult. Often we hear that if your crab has hairy legs, it is a male. This is not true.

The only way to determine your hermit crabs gender is to look underneath their 3rd set of walking legs, if you see 2 small dots (gonopores) you have a female, if there is nothing there, you have a male.



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