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hermit crab coenobita spp

Hermit crabs are nocturnal scavengers that will eat almost anything. Hermit crabs live in large groups in the wild and do best in groups of three or more.

hermit crab

Facts:

scientific name: coenobita spp
average adult size: 2 to 6 inches long, depending on species
average life span: 10+ years with proper care, depending on species
diet: omnivore

Will reach adult size in 2 years, depending on species and under ideal conditions; upgrade habitat size as your hermit crab grows.

Diet

Well-balanced hermit crab diet consists of:

  • High-quality commercial hermit crab food.
  • Recommend vegetables (spinach, carrots and romaine lettuce) and noncitrus fruits (mangoes, coconut and papaya) as treats.
  • Nuts, seaweed, brine shrimp and fish flakes can also be offered as treats.
  • Provide carotene and calcium supplements (such as cuttlebone).

Feeding

Things to remember when feeding your hermit crab:

  • Fresh, clean, chlorinefree water should be available at all times; may not drink from a bowl but will rely on moisture on plants.
  • Crush all pelleted foods before feeding; feed at night.
  • Hermit crabs appreciate variety in their diet.

Housing

  • Size - Appropriately sized and shaped habitat to accommodate adult hermit crab behavior and exercise, at least 10 gallons.
  • Habitat - Provide climbing décor and hiding areas; new shells should be a bit bigger than the current shell. Maintain 70 to 80% humidity by misting daily as needed (required to keep gills moist, prevent dehydration and ease molting).
  • Substrate - Sand, mixed with a mulchtype substrate such as coconut fiber bedding; can also include sphagnum moss; substrate should be at least 3 inches deep.
  • Temperature - Temperature gradient (80°F for the warm end and 70°F for the cool end); recommend low wattage incandescent bulb (appropriate for the size of the habitat).
  • Lighting - Hermit crabs are nocturnal, so you may provide a low wattage nocturnal bulb for nighttime viewing.
  • Water - Keep two shallow dishes of water in the habitat at all times: one with fresh, de-chlorinated water and one with marine saltwater with a specific gravity range of 1.021 - 1.026. The water should not be any deeper than 0.25 to 0.50 inch; any deeper and your hermit crab could drown. A sponge can be placed in the dish to help your hermit crab climb in and out, but change the sponge frequently to avoid bacteria growth.
  • House hermit crabs in groups of three or more, but do not house different invertebrate species together.

Normal Behavior

  • Hermit crabs are social and should be housed in groups of three or more.
  • Usually molt once or twice a year; will bury itself in the sand. Don’t disturb the process as the crab is very fragile. Protect the molting crab by placing a divider in the tank or moving the other crabs to another tank. Ensure proper humidity.

Habitat Maintenance

Thoroughly clean and disinfect the habitat at least once a week: place hermit crab in a secure habitat; scrub the tank and furnishings with a 3% bleach solution; rinse thoroughly with water, removing all traces of bleach smell; dry the tank and furnishings completely and add clean substrate.

Grooming & Hygiene

  • Place hermit crabs into their saltwater dish daily and allow them to exit at their leisure.

Health

Signs of a Healthy Animal

  • Healthy appetite
  • Active

Red Flags

If you notice any of these signs, contact your veterinarian.

  • Lethargy
  • Abandons shell and doesn’t return
  • Loss of appetite
  • Loss of limbs

Common Health Issues

Health Issue Symptoms or Causes Suggested Action
Mites Mites appear in the habitat or directly on the crab Completely clean habitat, replace substrate and bathe crab in lukewarm water. Ensure no mites are visible on the crab before returning to clean habitat.
Loss of limbs Loss of limbs can be due to stress from an improper environment (humidity, temperature, cleanliness) or fighting with another hermit crab. Ensure habitat is clean and properly set up with humidity and temperature within their preferred range or identify and separate the aggressor.

Sources

Ask a store partner about Petco’s selection of books on hermit crabs and the variety of private brand products available for the care and happiness of your new pet. All private brand products carry a 100% money-back guarantee.

Because all invertebrates are potential carriers of infectious diseases, such as Salmonella, always wash your hands before and after handling your invertebrate or habitat contents to help prevent the potential spread of disease.

Pregnant women, children under the age of 5, senior citizens and people with weakened immune systems should contact their physician before purchasing or caring for invertebrates and should consider not having an invertebrate as a pet.

Go to cdc.gov/healthypets for more information about hermit crabs and disease.

This Care Sheet can cover the care needs of other species.

Note: The information on this Care Sheet is not a substitute for veterinary care. If you need additional information, contact your veterinarian as appropriate.

Developed with and approved by a qualified veterinarian.