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Australian land hermit crabs.
This page is specific to the Australian land hermit crab Coenobita variablis. Other species found in other parts of the world can  differ considerably in diet and other essential requirements.

We do not sell direct to the public, though you may contact us for the nearest distributor of our crabs and products; or if you wish to become one of retail distributors: fish@oceanarium.com.au

 

Introduction:
The Australian land hermit crab Coenobita variablis (Aussie Crab) is distributed from Exmouth in Western Australia and across the Northern Territory border into northern Queensland. It is one of 15 known species of terrestrial shell carrying land hermit crabs. Land hermit crabs evolved from their aquatic cousins. Aussie crabs still rely on living by the sea for food, water, salt, and reproduction. Seldom are Aussie crabs found further than 500meters from the sea. They move a little further inland along some tidal creeks but don't follow the creeks far inland. Aussie crabs should be considered semi-amphibious as they principally live on land but do rely on a regular immersion or bath in sea water. They rely on the ocean to both breed and regulate their salt levels where as some other species of land crabs only return to the sea to breed. Australian land crabs lay their young in the sea from November to March where the larva follow the currents for a few weeks before settling to the sea floor and adopting a shell to live in, then they find their way to the sea shore to start life on land. Coloration of the Aussie crab varies considerably from white, cream, orange right through to deep reds. Fully grown they are 6-7 cm or as big as a tennis ball, these large crabs are believed to be at least 10 + years old. Crabs grow by moulting each year shedding their old skeleton (moulting). After moulting, the crab spends a few weeks hiding until the new one grows larger and hardens.

Collection:
Oceanarium is one of 5 licensed collectors of Aussie crabs in Western Australia. Currently, there are little regulatory requirements for the collection of Aussie crabs other than the limited number of operators. This is under review and we are working with Dept of Fisheries WA sharing our experience of more than a decade to help ensure a well managed fishery is set in place to allow a continuation of crab collection in a sustainable manner into the future. In the mean time, we limit ourselves treating the permission we have as a privilege taking all care to mitigate any environmental damage during our operations.

Crab populations on some beaches is limited or there are few large crabs  because there are not enough suitable or large enough shells for crabs to live in. Many of the crabs' original shells are returned to these beaches with limited shell after the crabs move into our new painted shells. The local crab population quickly takes advantage of this bonus. We go to extreme effort to access a large number of beaches in remote locations to spread the collection effort to mitigate any risk of population depletions in any one area. Always leaving plenty of crabs behind and not collecting smaller crabs.

Responsibility:
We have written this web page to help foster a more responsible attitude in keeping land crabs and further knowledge as to how to keep Aussie crabs healthy. Aussie crabs are not a child's toy to be played with for a while until it dies! Not to supply your crab with a few essential requirements is immoral! Aussie crabs can be a very good educational tool for teaching responsibility to an older child. Aussie crabs are an inexpensive pet and far less demanding than a cat or dog. They do have some specific requirements that if not met, your Aussie crab will suffer and die. A little care, thought, research and even a little expense to set up a well thought-out crabarium allows you to keep Aussie crabs successfully with little effort. These are long lived animals at least 10 years with some evidence that some species can live for more than thirty! There has been little study on life span of your Aussie crab and it could well be able to live beyond 20 years.

Requirements:
Aussie crabs have specific requirements, to keep healthy crabs with minimal effort consider these carefully in designing your crabarium.

  1. Temperature. If your crab gets too cold (+- 10C) once, it will suffer irreversible damage and will not recover. At around 20C your crab will become dormant failing to eat or drink  and after a few days it will likely die. Your Aussie crab comes from the tropics it buries itself 20cm under the sand for the coolest and driest months of the year rarely venturing out on only on the warmest of evenings or humid days to replenish water, feeding little during this time. They also avoid the heat of the day in summer seeking cool refuges in leaf litter and debris under shrubs seldom exceeding 35C. Keep your crabs in a crabarium where the temperature never falls below 20C even in winter at night! Try to maintain the temp at 28- 30C and your crabs will remain very active. There are a number of new heating products now available through your local pet stores. Under tank heat pads work well also heat rocks and other reptile type heaters.

  2. Humidity. Your crab must keep moist to breathe.  In the tropics when humidity is high in evenings or when it rains, the crabs are active. When the air is dry they remain in shelter huddled together to create a humid environment or under leaf litter. A lid covering the crabarium increases humidity. Damp sea sponge added to the crabarium is a extra source of moisture helping to increase the humidity. On very dry days, the crabs will even use the sponge for shelter. In the wild, crabs will hide in the humid environment under moist leaf litter, coco fibre in your crabarium can mimic this but should be replaced regularly. Crabs also gather in hollow logs or in piles of storm debris. The combined effect of 100's to 1000's of crabs carrying shells filled with sea water creates a terrific humid environment. Having 10-15 crabs in your crabarium and providing a few hollow logs or coco huts to choose from allows them to modify the humidity in a natural way. Keeping the humidity at 60%+ in the crabarium will keep your crabs active.

  3. Salt and water regulation. In dry conditions in the wild, the first action your Aussie crab takes each night is to go to the sea for salt water. When there has been rain or there is a heavy dew, crabs relish a drink of fresh water. But they will still return to the sea to flush the shell with sea water as a reservoir periodically. Aussie crabs rarely stray far from the sea and must regulate their salt levels access to salt water is compulsory. A popular conception is to give your Aussie crab a salt bath every week. Your crabs can survive with salt water alone and no fresh water at all. They cannot survive and thrive without salt water. They should always have access to a salt bath. Aussie crabs can drink salt water and expel excess salt and can detect and discriminate through airborne odours salinity levels of water bodies and differential drinking may be utilized for osmotic-regulation. (Greenway 2003) Provide your Aussie crabs with two bowls of water. One dish shallow of fresh water for drinking, so the crab can freely crawl in and out. Aussie crabs drown or suffer osmotic shock when immersed in fresh water for prolonged periods. The fresh water must be rain water, distilled water or if using tap water, an aquarium water conditioner or chlorine remover must be used. Also provide a second deeper bowl for a salt water bath. The bowl must be deep enough for the crab to immerse its' shell. Aussie crabs will flush the shell out of excrement and refill it with clean water so the water in this bowl must be changed regularly. Aussie crabs won't drown in warm sea water but still need a stepping stone or ladder to climb out. If the water is too cold it can quickly kill the crab. The salt water ideally is water collected from the sea, you can collect and store sea water indefinitely. You should store it in a cool light- proof container. If you don't have access to the sea, then you need to make up synthetic sea water. Don't use household salt this has a considerably different ionic balance than sea water. You need to use synthetic sea salt and mix as per instructions with de-chlorinated water.

  4. Shells. Shells provide your crab with protection and shelter to retreat into when threatened, reduce dehydration and provides a reservoir of salt and water that increases crabs survival time away from the sea. Spare shells are required to allow your crab to grow and replace shells they may damage in falls as they do love to climb! The lighter the shell, the more active and adventurous the crab becomes. Aussie crabs love to use light shells like land snail shells and bubble shells, but these are easily damaged in falls. Other shells like Tonna, Nautica and Babylonias are tough yet still allow the crab to still be active. Painted and decorated shells can add interest to your crabs and make them easy to identify. Make sure these shells have no toxic paint inside them and do not chip or chaff toxic paint. (Contact Oceanarium for the nearest distributor of our AAA grade painted crab shells). If enough spare shells are not provided, crabs will attack and kill each other in order to steal new shells.

  5. Food and diet. Unlike some other terrestrial crabs of the world ,Aussie crabs seldom find fruit along the beaches of northern Australia. Natural diet consists of seeds from grass, bushes and trees, with mangrove seeds and propagules being a favourite at the end of summer. Dead turtles, kangaroo's and fish etc are keenly sought when available and they will capture unwary insects. Though the majority of the diet is plant material, dung of kangaroos that rest in the cool sand under mangroves is eaten, fresh green grasses to a lesser extent and they will follow the previous tide line searching for any interesting tid bits that wash in from the sea. Aussie crabs will detect and react to food odours over a considerable distance. ("Coenobitids can detect food odours from distances exceeding 5 m (Dunham and Gilchrist, 1988) but they are attracted preferentially by the odours of foods that they have not eaten recently rather than foods recently eaten. This negative preference induction lasts 6–9 hours after a change of foods (Thacker, 1996; 1998) and presumably facilitates avoidance of particular nutritional deficiencies that might be incurred by reliance on a single food type or, alternatively, the accumulation of toxins.") (Greenway 2003) As a consequence ,Aussie crabs should be offered an alternating varied diet. Oceanarium provides a food appealing to crabs with good nutritional value, calcium, vitamins and protein (Crab Tucker) but you still should offer some fresh alternatives. Fresh leaves like lettuce, coconut, wheat flakes (breakfast cereal) a little fruit (apple, banana) and the occasional carrion like a small piece of fish or red meat, a small bone chicken, chop, etc, is always a favourite with your crabs and they will spend hours striping it bare! Only feed your crabs small portions and always remove any old stale food.

  6. Company. Aussie crabs are a social animal living in colonies from a few dozen to hundreds and in some cases even thousands. This adaptation gives them a better chance of survival in the wild. Shells are shared around when one crab out grows its shell others move in giving several crabs a new home as they all move up a size. As mentioned earlier the humidity of the colony is increased with the number of crabs present.

  7. Activity. Aussie crabs love to climb and to chew. Adding some mangrove climbing wood and hollow logs keeps Aussie crabs happy and healthy. Adding mangrove root stems gives the crabs something to chew. Aussie crabs in the wild spend much of the night chewing and eating these seed pods. Oceanarium has special licensing conditions to collect mangrove root stems. Marketed as "Crab chews" contact us for the nearest distributor. Aussie crabs are very good at climbing and care needs to be taken so they don't escape.

  8. Substrate. Providing the right substrate will reduce the maintenance of your crabarium and increase health or your crabs. The substrate should be deep enough for the crabs to bury. Substrate helps to keep your crabs warm on cold days and helps them keep moist when humidity is low. Aussie crabs often bury themselves while their new shell hardens after moulting. Its best to to set up the substrate bed at the opposite end of the crabarium to the water bowls or the crabs will make it too wet climbing in and out of the water bowls. The substrate should be replaced at regular intervals as it will become fouled with time. Some alternatives are:

Products.
Oceanarium has a range of products to keep your Aussie crabs healthy.
 

Climbing wood
Real mangrove wood collected from the beaches hermits live, our climbing wood gives your crabarium a natural look. Your hermits will love to climb and chew this wood. We also supply much larger pieces of wood and hollow logs for Perth shops only.

This product is also very popular with reptile keepers.

Sea sponge
Sea sponges are used to increase the humidity of the crabarium. Crabs will nest under the sponge on very dry days to keep moist.

Crab salt and tucker
Our crab salt is an artificial sea salt mix closely mimicking the ionic balance of natural sea water.

Our crab tucker is a mix of wild natural seed and protein pellets consisting of fish meal, shrimp meal, amino acids and vitamins for healthy crabs. Mimicking a natural crab diet.

Crab chews
Crab chews are a natural bounty Aussie crabs enjoy every summer, natural mangrove seed collected from the beaches hermits live.

Aussie crabs will spend hours chewing these tough fibrous root stems.

Coco huts
Our monster size coco huts are brightly painted with designs. Use coco huts for hermits to group together inside creating their own humid micro climate on dry days.

Food and water bowls
Tri dish for food and drinking water.

Swimming pool for salt water bathing.

Sea shells
We distribute an absolutely massive range of sea shells available in both larger and smaller sizes with over 100 painted designs, plus glitter shells and our nutty range of three dimensional shells including our hat range, bug range and character range.

Our range of natural sea shells are selected for durability and lightness to allow the crabs to be active, Aussie crabs just love to use these shells. We have selected a shell range to cater for crabs of all sizes from the smallest of crabs to our monster jumbo hermit crabs.