Wednesday, June 04, 2008

Hermit Crab

Data Sheet

Scientific Name: Paguroidea
Other Names: N.A
Origin: Beaches and Sea.
Adult Size: Varies, depending on species
Social: See below.
Lifespan: up to 20 years in captivity
Tank Level:

Minimum Tank Size:
10-15 gallons recommended for small individual hermit crab. A bigger
population would require bigger tank.
Eats almost any thing - they are scavengers.
Mission Impossible.
Ideal pH:
70-75 F

Tank setup:
An aquarium with 2-3 inches of gravel or sand is ideal.


It is almost impossible to tell when they are in their shell.


Most species of hermit crabs have long soft abdomens. To protect these abdomens from predators, the crab find a shell in which it can retract its body into. Most frequently hermit crabs utilize the shells of sea snails, marine gastropod mollusks. The tip of the hermit crab's abdomen is adapted to clasp strongly onto the columella of the snail shell. As the hermit crab grows in size it has to find a larger shell and abandon the previous one.

Accordingly to Wikipedia, there are about five hundred known species of hermit crabs in the world, most of which are aquatic and live in saltwater at depths ranging from shallow coral reefs and shorelines to deep sea bottoms. For the propose of this article, I will be focusing on the land hermit crabs.


Hermit Crabs can be housed in a 10 gallon aquarium with 3-4 inches of sand at the bottom at minimum. Ideally there should be two shallow dishes for water. One of the dish should contain de-cholorinated fresh water, and the second dish should contain salt water. To prevent your crab from drowning, it is ideal that the crabs should be able to get in and out of the dishes easily. Some wood is recommended as most land hermit crabs love to climb.

Hermit crabs love company, and ideally they should have at least 1 to 2 tank mates. Where possible, provide a variety of empty shells that are slightly larger than the one your crab is currently in. Get shells of slightly different shapes and styles and opening size, though rounder openings are usually preferable over slit-like openings. Hermit Crabs can be surprisingly fussy about the kind of shell they like, and if a good variety is not available fighting may break out over the "best" shells.


Hermit crab are scavengers and cheerfully eats almost anything, from fruits, dead fish, shrimps etc. You could feed them some commercial hermit crab food daily, supplemented with assorted fresh fruits and vegetables, cereal and whole grain bread items, and small pieces of fish and meat. Also offer some pieces of cuttlebone or ground oyster shell (or even boiled egg shells) for an added calcium source.

It is essential that you clean food dishes daily, and remove
uneaten bits of food from the tank. Check for food away from the dish as crabs sometimes drag food off to eat away from the others.

While Hermit crabs are not exactly nocturnal animals, but they are mostly active at night. They do all their eating and drinking at night, so do not worry if they do not seem to be eating during day time.


Hermit crabs cannot reproduce in captivity. This can only be done on the beach and when the phases of the moon are right, and also the eggs have to be laid in the seawater. When the eggs hatch as plankton, they have to develop into a hermit crab which can take about a month.


One disease known to attack hermit crabs as well as their relative crustaceans such as lobsters, crayfish and sea crabs is the 'shell disease'. This infection has also been given a number of other names, such as 'shell rot' and 'rust spot'. It appears as dark mysterious spots on your hermit crab's exoskeleton. They are different to the much tinier freckle-like spots you see on their skin. The fungi are believed to grow on the infected hermit crab's exoskeleton whilst feeding on its chitin. Shell disease usually infects those who have an injury.

If they lose a leg or claw, there is a risk that the fungi maybe able to do its dirty work. It is also important to keep the tank very clean, to reduce the amount of bacteria growth. Also make sure that the food you are feeding your hermit crabs is safe and that there is no mould in it. Hermit crabs can catch diseases from this. The disease also attacks those who are overly stressed, the main killer of hermit crabs.

Hermit crabs get very stressed when they are overcrowded or do not have much room to move around in. This is when they start dropping legs and claws, making themselves open to diseases. Remember, in the wild, hermit crabs travel for kilometres everyday for food and shells, so it makes sense that you should provide them large enough home to walk around in. Hermit crabs are able to free themselves from shell disease through moulting and shedding the infected exoskeleton off. Just make sure you have been feeding them plenty of calcium and protein to aid them through the stressful time.

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References Cited:

1. Wikipedia, Hermit Crabs, [Online], [Accessed on 4th June 2008],

2. Hermit Crab Paradise [Online][Accessed on 4th June 2008],

3. About Exotic Pets, Hermit Crabs, [Online],[Accessed on 4th June 2008],

4. Care of Hermit Crab, [Online][Available], [Accessed on 4th June 2008],

5. Shell Disease [Online],[Available], [Accessed on 4th June 2008],

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