Introduction
to Land Hermit Crabs
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Land hermit crabs are a great
choice of pet: exotic, clean, relatively inexpensive and
easy to maintain, and as an added bonus, they don't have
to take up much space.
However, they do have some basic requirements that need
to be met if they're going to thrive in captivitiy - the
purpose of this site is to help hermit crab owners understand
what those are and to offer some suggestions on way to meet
those demands.
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Lies, All Lies!
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| Coenobita clypeatus |
Hermit crabs aren't actually crabs at all. True crabs are crustaceans
from the infra-order
Brachyura, whereas all hermit crabs
are from the infra-order
Anamura and the superfamily
Paguroidea. Biologically speaking, they're much more closely related
to lobster, crayfish, and shrimp than they are to true crabs.
While most species of hermit crabs are aquatic, and can't live
very long outside the water, there are a few land-dwelling species.
Most notable among the land dwelling hermit crabs is the family
Coenobitidae, which encompases both the genus
Coenobita,
which contains the land hermit crabs most people keep as pets,
and the genus
Birgus, the giant coconut crab.
The hermit crabs this web site focuses on are the members of
the genus Coenobita. Several species in this genus are
sold in the pet trade, though which are available varies widely
by country. In the US it is common to find the following species
(roughly in order of their prevalence in most areas): C. clypeatus
(Purple Pinchers or Carribean Tree Crabs), C. rugosus
(Ruggies), C. compressus (Ecuadorians), C. perlatus
(Strawberries), C. brevimanus (Indos), and C. cavipes
(Cavs).
Hermit crabs also are not actually hermits. In the wild they
tend to live and travel in large groups. This makes good survival
sense, since as crabs grow, their former shells are automatically
available to smaller members of the group, and shell swapping
goes on down the line so that finding an appropriate shell at
the apropriate time isn't so unlikely. This is why it's best to
always have at least two hermit crabs in a tank - if possible
at least two of each species. They're used to the company. Their
name refers to the fact that they live alone in their little "house,"
like a hermit living alone in a hermitage.
Land hermit crabs are not bred in captivity for the pet trade.
Captive breeding land hermit crabs has been done, but it is not
currently a commercially viable process, so all the hermit crabs
found in pet stores are wild caught. While I don't feel this necessarily
precludes ethically buying hermit crabs, I do think it needs to
be a consideration of how land hermit crabs are housed and fed
in captivity. They need - for both their enjoyment and their health
- fresh foods in addition to the commercially available pet foods.
No commercially available pet food is nutritiously complete enough
that it should be hermit crabs' only food option. They also require
room to move around and things to climb on and hide under, so
they can remain active and relatively unstressed. Many pet stores
will try to market hermit crabs as good animals to keep alone,
or in a small plastic tank where there's no room for even their
basic room requirements, much less room for things for them to
climb on and hide in. For an animal who is used to having entire
beaches to roam, that's a pretty stressful change.
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Early Life
When hermit crabs mate, they stretch their bodies fairly far
out of their shell, and a male hermit crab passes his spermataphor
into a female crabs gonopores, fertalizing any eggs. Once the
eggs are fertilized, the female hermit crab will attach the egg
sac to her abdomen and keep it safe and moist inside her shell
until she reaches the ocean. When the expectant mother reaches
the ocean, she releases her egg sac into a tidepool, and her extremely
tiny, fully aquatic larvae hatch. Land hermit crabs go through
several molts in their aquatic stage before they ever even start
to look like hermit crabs. When they are almost mature enough
to come onto land, the hermit crabs start searching the ocean
floor for tiny, tiny shells. Once they find one and come onto
shore, they molt again and will lose their ability to survive
solely under water and become truely terrestrial.
Note: This does not mean that marine hermit crabs are young land
hermit crabs - they are a distinctly different group of hermit
crabs who spend their entire lives in the sea, with only brief
excursions onto the rocks of tidepools. These crabs will not survive
if they are subjected to the living conditions that land hermit
crabs thrive in.
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Geographic Distribution
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| Coenobita perlatus and
Coenobita rugosus |
I know there are many kinds of land hermit crabs currently unavailable
in the US pet trade - unfortunately I don't have exhaustive information
even on all of the species names, much less where each specific
species is found in the wild. Because of the limitations in my
own knowledge and the information that's currently available to
me, I've decided to concentrate on the land hermit crabs I do
know about - the ones regularly available for purchase in the
US.
C. clypeatus, or purple pinchers, are found in southern
Florida and all through the Carribean and even as far a south
as the northern coast of South America.
C. rugosus, or ruggies, are found from the east African
coast to the southwest Pacific.
C. compressus, or Ecuadorians, are found from the far
southern coast of California to the Peruvian coast.
C. perlatus, or strawberries, are found from Tanzania
to the southwest Pacific, as well as in Australia.
C. brevimanus, or indos, are found from the east African
coastline to the southwest pacific.
C. cavipes, or cavs, can be found from east
Africa to the western Pacific.
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