The hermit crab is a fascinating exotic pet that has gained popularity for being easy to set up and extremely low maintenance. They are hypoallergenic, clean, and generally very quiet. Unlike fish, they can be handled and taken out of their tank for short periods.
In order to set up a happy home for a hermit crab, it is important to understand the crab’s natural environment. Wild hermit crabs live along seashores and in tropical areas. They prefer a warm, humid environment with deep sand or mud to burrow in, and lots of water.
Pet hermit crabs should be housed in a glass tank with several inches of clean sand, sometimes mixed with sterile potting soil. There should be plenty of fresh, dechlorinated water available. Always use shallow dishes for the water, and provide ramps for small hermit crabs that may have trouble climbing in and out. Many owners find that hermit crabs enjoy lounging in a separate dish of salt water (aquarium marine salt rather than table salt), although fresh water should always be available.
A hermit crab’s hard exoskeleton makes excellent armour, but it does not hold moisture in as well as our skin. Humidity is an extremely important factor for keeping hermit crabs healthy, and a glass tank (rather than an open-sided cage) is essential. Although air should be able to circulate through the tank to prevent growth of bacteria and fungi, a partial lid of plastic or plexiglass can also help keep moisture in. In addition, spritzing the crabs with fresh, de-chlorinated water every day will not only help moisten them but will encourage them to become active, explore, and eat.
Wetted natural moss and plastic plants can provide humid microenvironments for crabs within a tank, and also make nice hiding places. Hermit crabs should always have a few areas of cover and crevices to be able to burrow and hide. Some will make their own by digging into the sand.
Hermit crabs also enjoy climbing, and driftwood branches or pieces of coral make good furnishings. The reptile section in any pet store usually has a variety of these structures. Be careful not to place a climbing structure too close to the side of the tank, as hermit crabs are surprisingly good escape artists.
Most hermit crabs do well at room temperature, but if the location of the terrarium is cool or drafty, or if you are having trouble maintaining humidity in the tank, you might consider installing a reptile heating pad under the sand. This type of heating pad is water resistant and will not become too hot and burn the crabs.
In the wild, hermit crabs are omnivorous scavengers, and will eat most anything they find. Commercial foods are available for pet crabs that will provide them with the nutrition they require, but fresh fruit and vegetables can also be given as a treat. All types of food in the tank should be changed every 24 hours so that it does not become moldy and make the crabs sick.
Hermit crabs are very clean, and produce very little waste. Although fresh food and water should be given every day, their terrarium should only need to be cleaned thoroughly about every month. An odd smell from the tank is usually indicative of a bacterial or fungal overgrowth, and means it is time for a cleaning, or that there isn’t enough air circulation in the tank.
All hermit crabs grow throughout their lives. As they grow, they need to upgrade the shell that they wear. A variety of different shells should be available to your hermit crab at all times, in a range of sizes. Some hermit crabs will change shells when they see a nicer one of similar size, but all hermit crabs will need a larger shell when they molt. Small crabs may molt as often as once a month, and the number of shells in your tank should reflect this. As your crab grows older, it will molt less frequently.
Molting occurs when a hermit crab has outgrown its current exoskeleton. After a period of inactivity (up to two weeks, often while buried in the sand), the crab will crawl out of its old exoskeleton and emerge in a new, soft pink skin, which will harden to become the new exoskeleton. Hermit crabs are very sensitive during this time and should never be disturbed while molting. The old exoskeleton should be left in the tank, as the hermit crabs will eat it in order to recover calcium.
When buying hermit crabs, choose active individuals with all their limbs intact – three pairs of walking legs plus one pair of claws. There should be no discolouration or damage to the head and thorax, and no visible parasites. You will probably have to watch the crab in its own environment for a few minutes to see its whole body, as most crabs will retract at least partly into their shell when picked up.
Hermit crabs can be handled safely by grasping the very back of the shell. Crabs that are handled gently and frequently are less likely to hide in their shell or to try and pinch you. If you do get pinched, and the crab does not let go immediately, a quick rinse with warm water will make them open their claws.
There are several species of hermit crabs available as pets, and you might like to do a little research on the type available at your local pet store. Hermit crabs are social and enjoy being kept in groups; however, be sure to choose crabs of a similar size or the larger ones might injure or eat the smaller ones. Two to four small crabs can live quite happily in a ten gallon tank.
Hermit crabs are curious and adventurous animals, and with a little care, they can be very entertaining companions, without the mess and bother of most other pets. Although small crabs can be quite cheap and will often survive for months or years with as little attention as a potted geranium, a well-nurtured hermit crab can live for 10-30 years.
By Jen Perret – Pets.ca writer