How to Care for your Crazy Crabs

Why does my crab need a regular saltwater bath?

When crabs are small and living in the ocean as plankton, they have a certain amount of salt within their body. After they come to land, this amount of salt is reduced, and because they only drink fresh water, they need to replace the salts in their body.

In the wild, the crabs get this salt from bathing on the shore, and from crawling around on wet beach sand as they look for food. Some would be obtained from the foods they find there. In captivity it is a very easy task to keep your crabs’ salt levels right. There are two ways you can do this:

Once a fortnight, you can give your crab a weak salty bath. By placing some room temperature water with a pinch of rock salt into a shallow bowl, either pick up the crab by his shell and gently dip his legs into it, or just let him crawl in and out at his leisure. You can leave this salty water in their cage, but don’t forget, they only drink the fresh water. Some people find it easier to do the bath every few weeks, and just supply fresh water everyday.

If you have beach sand in your crabs’ enclosure, the salts from this sand will end up mixed with their drinking water, so will create a somewhat saltwater bath. It won’t be as strong if you replace the water every day, so should do your crabs no real harm.

The salt water helps clean their skin too which can become sticky from fruits and mushy types of foods.

What about water?

Crazy Crabs need to drink plenty of fresh water. They cannot drink salty water as it causes dehydration. Fresh water should always be available, preferably in a shallow dish so that they can crawl in and out easily. Crazy Crabs will drown in a deep water dish if they cannot get out.
Terracotta bowls allow the crabs to grip the sides as they move in and out of the water. Make sure the sides are not too high for the crabs to climb over to get a drink.

Most tap water contains minerals and chlorine. If your tap water is high in metals, use cold boiled water instead. If your water has a lot of chlorine, leave it stand overnight before giving it to the crabs. The chlorine will evaporate from the water overnight.

Another way to remove chlorine from your tap water is to purchase some dechlorinator liquid from your aquarium shop. Read the directions on the bottle on how to use it.

Land hermit crabs store water both in their body and also inside their shells. Green algae can form inside the shell, this algae coating protects the crabs’ soft body from irritation from sand inside the shell or rough internal shell edges. This algae is harmless to the crabs’ health.

In the wild, land hermit crabs obtain moisture from the food they eat, also from dew on plants amongst the dunes in the early morning. This dew trickles down into the sand along the plant stems.

What do they eat?

In the wild Crazy Crabs eat a wide variety of foods. They eat almost whatever they can find either by the waves washing it up onto the beach, or scraps other animals leave behind. They are one of the many natural scavengers on the beach.

Their main diet consists of seaweed, cuttlefish, driftwood, dead fish and washed up fruit including mango seeds and mangrove seed pods. To a Crazy Crab, the beach is a banquet!

In captivity, they do like a varied diet, so they can be happily fed a number of different foods. “Crazy Crab Chow” is a great base diet which can be supplemented with some fruit and vegetables. These crabs eat around a match head of food every few days, they have very small tummies, so remember to remove uneaten fresh foods like fruit before it spoils. It will make their home smelly and bacteria can breed.

A little cuttlebone from the beach is a rich source of calcium for the crabs, they need calcium in their diet.

Why does it need a shell to live in?

These crabs are crustaceans and have a hard exoskeleton on the front half of their body, the rear half is soft and needs to be protected from predators, that is why they require a shell to live in. The main predators of land hermit crabs are birds and other crabs.

The crab squeezes its’ soft body into the shell backwards. On the end of their body is a small “hook” which then grips the internal spiral inside the shell. This keeps the crab securely inside the shell. It is most important that the shell is the correct size. If too large, the crab will have trouble lifting and carrying it around, and if too small, it just won’t fit. A little like buying new shoes! Crazy Crabs prefer a lightweight seashell as it has to be lifted slightly off the ground as the crab walks along. Heavy seashells drag and make climbing over obstacles more difficult.

Reproduction and How They Live

Land hermit crabs breathe air, and drink fresh water. Their life cycle has two stages, an aquatic stage and a terrestrial stage.

They begin their life as part of the plankton mass in the ocean. Reproduction is by way of a mass spawning on the beach, then the eggs are carried out to sea on the tide where they grow and develop. During this juvenile stage, they have gills similar to a fish and extract oxygen from the water to breathe.

The crabs move onto the land after growing to around 5mm where they move into their first sea shell home. At this stage of life, their gills change slightly and must be kept moist to allow oxygen to be extracted from the air. Humidity is important for both keeping their gills moist, and for extracting moisture for drinking. This is why the crabs venture down to the waterline at night to breathe the humid air contained in dew that falls on the beach.

What is a “Crazy Crab?”

Crazy Crabs are actually land hermit crabs. Their latin name is Coenibita variabilis. These crabs are native to Australia and are slightly different to species found in the United States. In the USA some species of land hermit crabs live in desert regions, with others are found along the coastlines in warmer climates.

In Australia, land hermit crabs are usually found along beaches and around mangrove swamps in the tropical northern regions. Land hermit crabs live in large colonies and move between the sand dunes and the high tide mark at different times throughout the day. Hermit crabs are nocturnal. During the daylight hours, they spend most of their time snoozing amongst low growing vegetation or buried in the sand. At night, they venture out to the beach searching for food, bathing and exploring new shells to move into.

In Australia, land hermit crabs hibernate inland from the coast underground, between late April and late August, the winter months.

What to keep them in

Crazy Crabs should be kept in a smooth sided container, such as a glass aquarium or plastic fish bowl or tank. As they are expert climbers, wooden or cardboard containers are not suitable. Crabs will chew on wood and cardboard.

Choose a container that suits the number of crabs you want to keep in it. Remember to make sure there is room enough for a food and water bowl as well as the crabs themselves. It’s no good having a small container where the crabs have to crawl through the food and water to move about. Also consider the decorations and climbing objects you want to have in their enclosure.

Most pet stores carry a wide range of suitable containers, and they are not expensive, but it really depends on what you would like your crabs to live in. If you have other pets, such as cats, it may be an idea to make sure the crab home has a lid. If the tank gets knocked over, the crabs will quickly escape if there is no lid to keep them inside.

On the bottom of the Tank

On the bottom of the tank you can use aquarium gravel, beach sand, untreated wood shavings or river pebbles. The gravel or sand does not have to be deep as the crabs do burrow and you can’t see them if they are buried too deep. The floor needs to be kept dry as wet sand and high humidity can create a smelly and slimy environment for your crabs.

With gravel, you can wash the gravel when it gets dirty. Just use some hot salty water, not soaps or detergents. Salt is a natural sterilizer, so won’t leave any residue that can harm the crabs. Rinse well and leave out in the sun to dry. It is handy to have enough gravel so that when some is being used, the other is being stored dry for use when the first lot needs washing. Never use sand from your garden, it could have chemicals in it which may harm the crabs.

Winter Housing

In the winter months, a wet, soggy floor, and cold weather can make crabs very unhappy. Untreated wood shavings, chips or sawdust make a great place for your crabs to snuggle down and sleep. When the weather gets cooler, move the crabs to a room in your house where the temperature stays fairly constant. Don’t put them next to the heater.

A sunny window sill during the day will warm the sawdust, then when you bring the tank back into the house, the crabs will stay snug and warm in the sawdust through the cold night. The window sill is the coldest place in the house at night, glass is a poor insulator, so bring them away from the window at night.

Summer Housing

In the summer months, crabs will be more active because they come from a tropical environment. Drinking water is very important so don’t let your crabs go thirsty.

Keep the crabs inside or under shade during the summer. Too much direct sunlight can make them overheat, and their shells can get very hot. If you want to take them outside, keep them under the patio or in the shade.


In a tropical environment, the temperature remains fairly constant. If where you live, you get cold winters and hot summers, there are some points to remember to keep your Crazy Crabs happy and healthy, in all seasons.

In the winter, keep your crabs in a part of your house that keeps a stable temperature. Concrete floors and ceramic tiles are cold, so keep your crabs’ home on a bench or cupboard off the floor. If it gets really cold where you live, a small light in the crabs tank may keep it warmer. Suspend the light from the top of the tank, but don’t put the electrical cord in or your crabs will crawl up it and escape. A low wattage globe, around 15watt is recommended.

Heating pads are also a great way to keep them warm in the winter. The pad plugs into the electric socket and attaches to a foam pad which sits under the tank. The devise only draws 8v so is safe for pets and children. The gentle heat radiates up through the gravel or sand to around 30 degrees celcius.

Heating pads for crabs are the same as the ones used for reptiles. Try a pet store near you that stocks them for lizards and snakes. These pads provide a gentle heat which will not cause your crabs to dehydrate.

Note: It is illegal to keep native reptiles as pets in Western Australia, so accessories such as these may have to be purchased from a company in the eastern states, where reptile keeping is a legal activity.

If we do manage to find a supplier for these, we will post it onto the website.


Humidity is the amount of water vapour in the air we breathe. Crazy Crabs require high humidity to keep their gills moist and allow them to breathe properly. When humidity is low, the air is drier and they become inactive and some become dehydrated.

The crabs can suffocate if the air is too dry. To ensure you have enough humidity in their enclosure, make sure there is plenty of water in their drinking bowl. Adding some sea sponge can help the humidity too. The sponge absorbs water creating a damp sponge, which adds to the humidity. Crabs eat sponge in the wild so it won’t hurt to have some in their enclosure, both for climbing on, and for humidity.

Decorations for your Crab’s home

Crazy Crabs just love to climb and explore! Pieces of coral, sea sponge, driftwood, rocks and ceramic aquarium ornaments are all great for Crazy Crabs to play on. Make sure your decorations don’t lean onto the rim of their house, they are great climbers and can escape quickly. Next time you visit the beach see what treasures you can find for your crabs house!

Your pet store will have a range of ceramic and resin ornaments such as branches, boats, stones and other shapes for you to choose from.

Spare Shells

Crazy Crabs change shells throughout their lives as they grow. Growth is slow, around 1-2mm per year so spare shells should always be available just incase your crab needs a better fitting shell. In the wild, shells can be hard to find, so your crab may need a new shell as soon as you buy it. Lightweight shells are best as the crab has to be able to carry it for a long time, all day, every day.

If your crabs fits snugly into his present shell, when he withdraws back into it, no legs hang out past the opening, this shell is the correct size and fit. If they do not fit snugly in the shell, their legs hang out, and a new shell is required.

When selecting shells for your crabs, the size of the opening will determine whether or not the shell will fit your crab. Have a look at the opening on the shell that your crab has on already, then get a new shell with just a slightly bigger opening. As the crabs grow, their legs get thicker, so need more shoulder room in their shells. A selection of new shells is better than one shell that just does not fit your crab. If you have a few crabs, they will probably all swap and change shells amongst themselves.


As Crazy Crabs are crustaceans, they have their skeleton on the outside of their body, it is called an exoskeleton. In order to grow, once or twice a year, they shed this outer skeleton.
Some crabs become sluggish and inactive when they are about to moult, others spend more time than usual in and around the water bowl. The crabs drink more water in order to make their body swell slightly in order to ‘crack’ their outer skin and this helps the skin to be discarded in a single piece. The crabs only shed the front half of their skin, as the back half is soft, it is not covered by this hard outer skeleton.

When crabs moult, it is a very traumatic time for them, so you should take care not to touch them too much whilst they are moulting. After moulting, the skin is usually left on the floor. You could be mistaken in thinking it is another crab. If you do find a skin, you can leave it there. Crabs will eat this skin as it is rich in calcium. They may eat this discarded old skin before you know they have actually moulted.

You will know when your crabs have moulted as they will appear to be a slightly different colour. Their legs and body may appear to be a pinkish/orange colour and quote blotchy. At this time, their outer skin is very soft and easily damaged.

Crabs will usually bury in the sand for a week or so while their skin hardens up. Do make sure there is plenty of food and water in their enclosure even if they are inactive. They feed mainly at night so will sneak out and feed during the night. While their skin is soft, don’t touch the crabs, just leave them alone but make sure they have plenty of food and water.

As Coenibita variabilis hermit crabs come in many colours, whites, greys, browns and pale orange tones, your crab will return to the original colour it was before moulting once his skin has hardened.

Once your crab has molted it is a good idea to remove him from the other crabs and set him up in a small isolation tank alone, with food and water, to allow him to harden up in peace and quiet, away from other crabs.

Some crabs change into a new shell after moulting, others return to their old shell.

Lost Limbs

Crazy Crabs can lose legs and claws for many reasons. They do regenerate these lost ones over several moults. The legs will grow back with each moult though they will appear smaller, but will increase in size each time the crab moults. Crabs lose legs through fighting with other crabs, stress, and through illness.


Crazy Crabs live in large colonies in the wild, with members of all shapes and sizes. As there is competition for new shells, this can lead to some crabs trying to pull others out of their shells so they can steal them! Sometimes the crab being pulled by the other crab will drop a leg off to save himself. If you have several crabs, make sure there are plenty of shells to choose from.

Crabs will also fight if they are overcrowded. Bigger crabs tend to push smaller ones out of the way as they move around the tank. The solution – provide some more climbing objects so the crabs can spread out a little, or get a larger tank for your crabs.

In captivity competition for food is not a problem as numbers are not as large and adequate food is provided for them by you.


Stress among hermit crabs can be caused by:

  1. Overcrowding and bullying
  2. Extremes in temperature, too hot or too cold
  3. Being dropped onto hard surfaces
  4. A crab kept alone

Stress can make crabs inactive and sluggish. They can also come out of their shell and walk about ‘naked’. Some crabs just crawl off into the corner and will not return to their shell. This leaves them open to attack from other crabs, and they have no protection. It is not normal for these crabs to walk about without a shell on their soft body.


Many, many Crazy Crabs fall victim to poisoning without their owners realizing it. It is very important to remember not to spray any chemicals near your crabs, or where your crabs play.

Cleaning chemicals such as furniture polish, insect sprays, room deodorants and fresheners can kill your crabs if the spray gets into the food and water bowls. Crabs then drink or eat the contaminated food and water leading to poisoning and death. As they have very small bodies, only a small amount can have devastating effects.

Another area for concern, is placing your crabs onto carpet for recreation. Many carpets are cleaned with chemicals, and much of the chemical is left as residue within the carpet fibres after the carpet has dried. Crabs pick up these particles of soap and cleaning chemicals when they walk about on the carpet.

It is safer to play with your Crazy Crabs on tiles or linoleum floors which are cleaned and rinsed so no residue remains.

Keeping your crabs in any room in the house where there are sprays being used can cause poisoning. In the bedroom, hair sprays and deodorants are chemicals toxic to crabs also.

Signs of poisoning include the crab dropping its’ shell off and crawling about naked. They may also head for the water bowl and stay there. The shell is held on by muscles in the crabs’ body, when they are sick, they cannot hold the shell on. They cannot wash off toxins on their bodies, and will pull the affected legs off. As their skin is porous, toxins can get in through their skin and kill them. Poisoning is usually fatal.

Remind mum to cover the crabs’ home when spraying household cleaners around your house.

Life Expectancy

In the wild, Crazy Crabs have been known to live for around 50 years. Growth in these crabs is around 2mm per year, so to reach the size of a tennis ball would probably take around 50 years! They change shells throughout their whole lives as they grow bigger.

In captivity, life expectancy is really a matter of how well they are cared for. Some people have them for years without any trouble, others owners have problems. If you follow the simple rules of caring for them, your Crazy Crabs can live for a very long time indeed.

Handling your “Crazy Crabs”

Crazy Crabs no matter what size, need to be handled with care. All crabs need to be placed on an open palm and allowed to walk from hand to hand. Don’t let your crab fall as this can cause injury and even death.

Never dangle him by the shell, he can reach around and nip you on the finger as he is frightened and thinks you may drop him onto the floor. In the wild, birds pick them up and carry them away, so keep them on a steady open palm of your hand.

Crazy Crabs will usually only bite when they are frightened. It is more of a pinch than a bite and causes no damage to skin.

Larger crabs crawl quickly so handle them accordingly.

If your Crazy Crab does pinch you, lay your hand flat on the ground and let him crawl off. He will feel safe knowing you won’t drop him. Or you can run him under cool water instead.

Games to play with your “Crazy Crabs”

Many crab owners take their crabs everywhere they go, to school, friends’ homes or even on holiday! If you have friends with Crazy Crabs, why not get together for some fun activities such as Crazy Crab Races, or climbing competitions!

Classroom Pets

Many schools here in Western Australia have Crazy Crabs in the classroom. They make great classroom pets, and don’t require complicated care. Ask your teacher about getting some Crazy Crabs as your classroom pets!

Where to buy your “Crazy Crabs”

Merv Cooper’s ‘Crazy Crabs’ were first introduced to the Australian pet marketplace back in 1979. We were the first company in Australia to market these cute little pets.
The name “Crazy Crabs” is a registered trademark and can only be used on our merchandise sold by our company.

Crazy Crabs has become a household name to Australians and these pets seem to have never gone out of style.

They are suitable for all types of people, whether you live in a flat or unit, a caravan or even on a boat. They are very easy-care and fun to keep as pets.

If you want to purchase a real “Crazy Crab” look for the bright pink posters in your local pet store window. These stores support our company and can supply you with all the tips and accessories for your Crazy Crabs. All our products have the name/trademark of “Crazy Crabs’ on them.

These stores know how to care for your crabs so you can count on them for expert advice about your Crazy Crabs and their care.

If your local pet store cannot give you the answers to your questions, or doesn’t stock Crazy Crabs, you can always contact us for advice.

Merv Coopers’ CRAZY CRABS
P.O. BOX 7037, Safety Bay WA 6169
Telephone: 08 9528 2722
Fax: 08 9528 2733

Our retail store is situated at 12 Ambrose Street, Rockingham WA 6168

Remember – If you want to email us with a question, please make sure your return email address is valid and can receive mail. There is no way of us answering your question if your email address is invalid and our reply to your question gets returned to us undelivered.

How to purchase a healthy Crab

Visit your local pet store and see if they stock Crazy Crabs. There are a number of things to look for at the pet store, to make sure you buy a healthy crab.

  1. Is there a good selection of crab sizes in the display
  2. Do they have sufficient food to eat and water to drink
  3. Are the crabs active or all asleep
  4. Does the shop have a range of accessories for Crazy Crabs
  5. Is the crab display clean or dirty
  6. Does the crab display tank smell bad
  7. Does the shop have a large pink ‘Crazy Crabs’ poster & accessories on display

When choosing a Crazy Crab, look for a crab that is moving about. They do sleep during the day, this does not mean they are unhealthy or sick.

Ask the staff to turn a few crabs over, this usually gets them moving around and gives you a chance to see them properly.

Choose a crab that is active and has all it’s legs, antennae and two eyes. Leave the ones that stay asleep. Active crabs make better pets and respond well to being handled.

On the bottom of the Tank

On the bottom of the tank you can use aquarium gravel, beach sand, untreated wood shavings or river pebbles. The gravel or sand does not have to be deep as the crabs do burrow and you can’t see them if they are buried too deep. The floor needs to be kept dry as wet sand and high humidity can create a smelly and slimy environment for your crabs.

With gravel, you can wash the gravel when it gets dirty. Just use some hot salty water, not soaps or detergents. Salt is a natural sterilizer, so won’t leave any residue that can harm the crabs. Rinse well and leave out in the sun to dry. It is handy to have enough gravel so that when some is being used, the other is being stored dry for use when the first lot needs washing. Never use sand from your garden, it could have chemicals in it which may harm the crabs.