Crabitat
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While most pet stores sell land hermit crabs
as an easy pet to take care of, they can actually be fairly
delicate little creatures. Most pet stores will tell you
they just need a pool of water, a sponge for humidity, a
shell for food, some gravel or calci-sand, and maybe a little
cocohut to hide in, usually all crammed in a small plastic
"tank" with a slotted lid.
In reality, hermit crabs, like any other animal, need a
better habitat than that to truly thrive. I can't think
of any animal (apart maybe from some insects) that I would
really keep in a home like that on anything but a very temporary
basis. We do have one, as that is what the place we originally
got our first hermit crabs recommended. Now we use it as
a carrier if we need to transport just a few of our hermit
crabs, or as an isolation tank if one of them are sick or
suddenly aggressive.
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Items in bold below are things you will need to purchase to create
a really good habitat (crabitat!) for your crabs. Click HERE
for a printable shopping list.
Habitat
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| 40 gallon breeder crabitat |
The best cage for a land hermit crab is a glass or plexiglass
aquarium with a glass or plexiglass lid. It does not
need to hold water, so old or leaky aquariums are perfect! Hermit
crabs are crustaceans who breathe through a system of modified
gills, so they need their crabitat to be both humid and warm.
Glass holds in warmth and moisture much better than plastic. The
other common type of cage you see sold for hermit crabs are metal
cages. While on the surface this might seem like a good solution
(light, portable, and instant climbing surface), not only does
it not hold in any heat or moisture, but it's made of metal, which
land hermit crabs are very sensitive to. They should really never
be kept in anything but a glass tank in the long term.
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Gauges
Since I mentioned heat and humidity, the perfect temperature
for most land hermit crab species is 78°F, with approximately
78% humidity. A good temperature range runs from 70° -83°F,
and about the same range of % humidity. If the habitat falls out
of that range, the crabs may become lethargic, or they may even
go "naked" (run around without a shell). A few species,
most notably the Coenobita perlatus, or strawberry hermit crabs,
prefer a slightly higher temperature/humidity, though it should
still never be above 85°F/85% for long periods of time. When
exposed to prolonged extreme heat or dry air, crabs may die. Because
this is a delicate balance to keep, it is very useful to have
a thermometer and hygrometer
in your crabitat.
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Heat Source
For these reasons, you will also need an under tank heater
(UTH), which will attach to the bottom or side of your tank. Be
sure to buy one made specifically for terrariums, and at an appropriate
size for your tank. Most UTHs will come with little plastic "feet"
to stick under your tank to give them circulation space so they
are not a fire hazard. If they do not, you will either need to
find something to keep the UTH from being a fire hazard, or you
will need to place it on the back of the tank.
If you have a larger tank (more than 29 gal), you may have to
supplement the UTH with a low wattage light in an aquarium hood,
but be very careful and make sure the tank is at a stable temperature
and humidity before moving the crabs in as lights can dry the
air out. It is also very important to provide your hermit crabs
with appropriate day/night cycles, so never keep a day light on
at all times. Either use a timer or use a moon light bulb at night.
One thing that we use and find very helpful is a rheostat with
an external probe. The probe goes into the crabitat, and the guage
is dialed to turn off at the high end of the appropriate temperature
scale. Once heat sources like lights and under tank heaters are
plugged into it, it will turn them off if the temperature in the
crabitat becomes higher than the specified temperature.
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Substrate
Land hermit crabs need a substrate they can
dig in. Hermit crabs stay at a comfortable temperature by moving
to cooler or warmer areas of the tank, or digging down under their
substrate. Good substrates include play sand, aragonite, calci-sand
and coconut fiber bedding (which is sold as Eco-Earth or Forest
Bedding, among other brands). These can be used exclusively, mixed,
or put in as separate sections of substrate.
Since we first got our hermit crabs, we have used all of these
substrates at various times. So far, my favorites have been aragonite
and coconut fiber bedding, however aragonite is very expensive
(about $20 for 10 lbs.) unless you catch it on sale somewhere,
and we've found it works really well mixed with playsand, which
tends to be finer than aragonite.
Play sand is probably the best cheap alternative (about $3 for
50 lbs), but it can harden if it dries out, especially under the
water dish. Both coconut fiber bedding and sand (excluding calci-sand)
should be kept damp so that they will contribute to maintaining
your crabitat's humidity. Sand should be kept at sand castle consistency,
so it is damp but not mucky. This can be maintained by dumping
small amounts of water on sand. Coconut fiber bedding can be kept
damp by misting it occasionally. In order to promote mold resistance,
make your coconut fiber bedding using a dechlorinated salt water
mixture (I usually use a solution of the dechlorinated fresh water
and dechlorinated salt water I keep on hand for the crabs' pools
anyhow).
Our crabs dig a lot of holes and tunnels in the aragonite and
play sand, but when molting seem to prefer the coconut fiber bedding.
We have had successful molts in sand, but when both were offered,
every molt we had was in the coconut fiber substrated.
While calci-sand may work as a substrate, it has several drawbacks.
It molds easily and smells bad and clumps when it gets wet. It
can work well in a small area of your tank if it's kept fairly
dry, but overall if you must have it, it works best as a calcium
supplement fed in a food dish or feeder shell.
Substrates that should NOT be used for land hermit crabs include
cedar chips, any sort of wood shavings (especially pine!), potting
soil, regular dirt from your garden/yard, crushed walnut shells,
and gravel. Aquarium gravel may be OK as a substrate in a small
part of your tank, but it should not be used as a main substrate
since hermit crabs cannot easily dig in it, and water tends to
pool under it. I will note that organic potting soil, in pots,
can be put in the crabitat if you have a real plant you'd like
to add (and the hermit crabs will snack on it!). Non organic potting
soil may contain pesticides or other chemicals that might be harmful
to your crabs. Coconut fiber bedding will also support most plants
that tolerate damp, tropical climates, though, so a pot and soil
may not be necessary unless your coconut fiber is very salty.
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Water Source and Supplies
A water dish for fresh water and a water
dish for salt water. These dishes should be nonmetallic
and deep enough that the crabs can dip their shells in it if they
want, but shallow enough that they can still easily get out of
the water. Once again, strawberry hermit crabs are a little special
here: they require that their salt water dish is deep enough for
them to totally submerge, but not much deeper. If you are worried
about smaller crabs, be sure to add a something for them to cling
to and ways for them to get out of the water, or add a sloping
bottom using aquarium gravel or some other surface they will be
able to grip and pull themselves out with around the edges. Despite
using modified gills, land hermit crabs cannot breathe for long
periods of time under water, and will drown if they're submerged
too long. If water dishes are deep enough for them to get water
in their shells, hermit crabs will not need to be regularly bathed,
since they will be able to do it themselves!
The chlorine, chloramines, and other heavy metals found in tap
water are bad for hermit crabs, and can cause lasting damage if
they are exposed to them for extended periods. All their water
should be treated with a dechlorinating solution
that does not say it promotes a slime coat in fish. Salt water
must be made with a de chlorinating solution and sea salt.
Table salt contains man made iodine, which is poisonous to crabs
with prolonged exposure. Sea salt can be readily bought in the
aquarium section of any pet store. For most crabs, you should
use the package directions for hatching brine shrimp, however,
strawberry hermit crabs require a higher salinity. It's better
to make the solution a little too strong than too weak, as the
crabs will regulate the salinity in their shells by diluting the
salt water with fresh water.
You should also have at least one undyed sea sponge
in the fresh water tank. This will help raise the humidity levels
in your crabitat. It is nice to have more than one, so you can
switch the sea sponge out about once a week, so you can clean
it and let it dry so there is less chance that it will mold. I
have never seen a store that carries hermit crabs NOT have these.
Once a sponge is dry, it can be microwaved for a few seconds to
sterilize it, but it should never be microwaved while wet - they'll
shrink!
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Decorating Essentials
Another big essential is for your crabs to have someplace
to hide from the day. You will find lots of ideas in
the reptile section of the pet store, or you can get creative.
We have caves, half logs, coco-huts (made from half a coconut
with a door cut in), aquarium decorations, fake plants, reptile
moss, and driftwood for our hermit crabs to hide in. You can also
make a cheap hiding place for them with a small terra cotta pot
turned on its side and half buried in the substrate. Be creative!
So long as it's clean, nonmetallic, not made from pine, and not
likely to chip paint or other potentially toxic substances into
the crabitat, it's probably fine for your crabs! Each crab should
be able to find a fairly roomy hiding spot during the day - they
will pile together if they want to, but they shouldn't have to.
Hermit crabs may get lethargic if they are bored, so save room
for some TOYS (which often double as hiding spots,
handily enough). They love to climb, so anything that will give
them purchase will entertain them. Driftwood, caves, coco-huts,
cholla wood, even terra cotta pots will turn into climbing toys
for your hermit crabs. If something looks like it will be too
slippery to climb, you can drape fish net over it or otherwise
make grooves in the surface. It doesn't take much for a hermit
crab to be able to climb! But be careful about putting things
too close to the lid, as they are cunning little escape artists,
and are much stronger than they look! Strawberry crabs in particular
need lots of things to play with, climb, knock over, and generally
destroy.
While only partially decorative, another thing you must obtain
for the crabitat is extra shells about the right
size for your crabs. A good rule of thumb is that every crab should
ave at least two choices about the same size and weight as their
current shell (or slightly bigger). Shells should not be cracked
or chipped if possible. If extra suitable shells are not provided,
a hermit crab may attack or even kill another hermit crab for
its shell.
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Food Source
Any crabitat needs a food dish as well. I use
various scallop shells (and occasionally other similar flat shells)
as food dishes, and I usually keep two in the tank at a time,
one with either a treat or a calcium source, and one with a commercial
or homemade dry food mix. These can be elaborate, attached to
plastic trees, grapevine, or other tank decorations for your hermit
crabs to climb on, or they might be just simple seashells. For
a larger tank or more crabs, you may want to add more food dishes,
or obtain a bigger food dish. For some larger food items, like
shrimp or bits of fish, I also have a larger ceramic food dish
for the crabs to climb into and eat.
The only other supply you should need is food,
which will be explained in more detail on the Feeding
page.
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