Hermit Crab Care Guide

Hermit crabs make adorable pets but these little packages of cuteness are surprisingly high-maintenance and require very exacting care.

Hermit crabs are widely believed to be easy to care for, and ideal first pets for children. Neither of these beliefs is true. Unfortunately, hermit crabs are very difficult to keep healthy, and they should be kept in groups. Not only are hermit crabs are not hermit-like at all, they are gregarious partiers who will keep a crab-party going all night.

You’ve probably seen the clear plastic critter-carriers and one-gallon fish tanks where hermit crabs are sometimes displayed. These are not safe homes for hermit crabs. In fact, if the critter-carrier has a standard “berry-basket” top for ventilation, the crab inside is probably already dying a slow and painful death. Hermit crabs breathe air through modified gills. They will drown in water, and they have no lungs. If the gills ever dry out, the animal is in serious trouble. The resulting death by suffocation can take months, but it is inevitable. Therefore, maintaining sufficient humidity in the hermit crab enclosure is very, very important.

This brings us to the topic of equipment.

ESSENTIAL EQUIPMENT

This list is a very rudimentary introduction to the equipment needed to keep crabs healthy.

  • An aquarium tank, marine terrarium, or large covered enclosure strong enough to contain wet sand. Be sure the cover is tight enough to prevent the crabs from pushing their way out, that some air can get in, and that it keeps moisture inside the tank;
  • Water-conditioning fluid, to neutralize chlorine and its by-products in the water;
  • Safe sea salt, of the kind sold for marine fish and crustaceans;
  • Safe sand, enough to be a few inches (15cm minimum) deep in the tank;
  • Water dishes, sea sponges, shallow food dishes, and a slotted scoop to remove uneaten food from the sand;
  • Quarantine tank, which is basically the full set-up in miniature, for safe moulting;
  • Hidey-huts for the crabs to relax in, during the day;
  • Extra shells of the correct sizes and shapes, at least three per crab;
  • Thermometers for the sand and hygrometers for the main tank and the quarantine tank;
  • Branches and rocks to climb on;
  • Moss and extra sea sponges for soaking, to help keep the humidity above 75%; and
  • Heater for one end of the tank: most hermit crab species like a temperature of 75-80F/24-27C on the warm end of the tank.

EXERCISE

These cute little crustaceans will keep themselves fit, presuming their tank is big enough. They love to climb, and crawl, and pull. If you are very careful, you can “walk” them across your hands held low over a soft surface. As the crab moves across one hand, bring the other one around in front. To do this, your hands need to be positioned side to side, and not fingertip-to-fingertip. Otherwise, the surface will be too narrow and the tiny crab will become frightened.

FEEDING

Hermit crabs are beachcombing scavengers. As omnivores, they require both meat and plant-matter in their diets. Unfortunately, the commercial crab foods do not make a good diet for hermit crabs. They tend to contain preservatives, but some are safe enough: read the ingredient list. The real problem is that commercial foods are boring. Crabs don’t like to smell the same meal twice in a row. They will be happiest if every meal is a little different: some fish and a touch of apple today, perhaps some chicken and seaweed tomorrow.  (Thacker, 1998).

Wash all fruits and vegetables before feeding them to your crabs, and use de-chlorinated water to do it. Always do everything you can to keep your crabs away from chlorine. Meat can be raw or cooked, or even freeze-dried, but avoid preservatives (including salt).

That’s not to say that everything always needs to be fresh. Stock up on an assortment of jars of baby foods. Keep some freeze-dried daphnia, bloodworms, tubifex, and shrimp on hand from the aquarium section of the pet store. Offer a few pieces of low-salt catfood.

Crabs need calcium. The simplest way to provide it is to drop a couple of cuttlebones onto the floor of the tank. Cuttlebone is sold in the pet-bird section of the pet store.

Unlike many animals, hermit crabs need two kinds of water bowls: one with freshwater and one with salt water. The salt water cannot be made with table salt, because of the iodine in it. Both bowls need to be big enough for the crabs to submerge themselves, and easy to crawl out of so the crabs don’t drown. A piece of sea sponge in each bowl makes a convenient safety raft.

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