Hermit
Crab Care
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So, the crabitat is up and running,
the temperature and humidity are in the right range, the
right kind of food has been distributed, the crabs have
been chosen and named... what next?
It's important to realize that while keeping land hermit
crabs doesn't have to be a time consuming affair, and is
certainly less involved than keeping most mammals, you will
have to spend some time maintaining the crabs and their
crabitat.
This is an area where it's really important that land hermit
crab owners educate themselves, because there are so many
"basic upkeep" things that are very controversial
in the hermit crabbing community. |
Crabitat Conditions
It is important that a hermit crab owner is able to maintain proper
conditions for land hermit crabs in their crabitat. Keeping the
crabitat in the right range of heat and humidity is probably one
of the most difficult things for new crabbers to learn, because
every tank is going to be different. Different climates, and even
different houses within those climates put the crabitat under
different conditions. Someone who keeps their house at 65°F
is going to need more oomph to their crabitat's heat system that
someone who keeps their house at 75°F.
Someone who lives in Phoenix is probably going to have to worry
more about humidity than someone who lives in New Orleans.
If you're able, this is why setting up a tank ahead of time and
figuring out what the pitfalls will be for stablizing it in your
particular situation is a really good idea. This isn't always
practical though, especially if you've already got your crabs
and they need someplace to stay NOW. Even when housing hasn't
been at a premium though, sometimes it's hard to make yourself
wait to put the crabs into their new, bigger, better home. I have
to say, I've never managed to wait long enough for a new tank
to stablize before putting crabs in! I have no self control.
New (and experienced!) crabbers are often looking for new ways
to improve the humidity in their crabitats. The easiest way is
to make sure that your substrate is damp. Coconut fiber bedding
and damp sand can improve the humidity in your crabitat incredibly.
Another way to improve humidity in your crabitat is to mist things
in the crabitat that are likely to 'wick' the moisture out into
the air. Things of this nature include coco-huts, driftwood, and
terra-cotta items. Because of the danger of mold, I usually do
any misting with a weak dechlorinated salt water solution. This
helps inhibit mold from forming on mold prone items like coco-huts
and wooden items. There are also humidifiers made especially for
hermit crabs and tropical reptiles on the market, which can be
useful if you have an especially large tank or especially dry
conditions. You can also make
your own humidifier.
As far as heat goes, there aren't a lot of creative options.
You can place an under tank heater on your crabitat. These are
generally rated for the size of tank they're meant to go on, and
will warn you not to use it if it will harm a certain tank material
(ex. plastic). Usually under tank heaters come with little plastic
feet to provide circulation and prevent the surface the tank is
sitting on from becoming too hot. You can also buy a hood for
your tank, and use flourescent lights. Many crabbers also use
a clamp on lamp with a day bulb and/or moonlight several inches
above the crabitat. Be careful using heat lamps, as they may severely
dry out your crabitat. Generally, you don't want more than 1 watt
per gallon, and I think it would definitely be a better idea to
guess low the first time, and move up to a higher wattage bulb
if necessary later. If you do use lights it is important not to
keep day lights on 24 hours a day. Crabs need night time - too
much exposure to day lights may confuse their biological systems
and inhibit their ability to molt. A good solution for this problem
is to use a moon light at night - these can be found in most aquarium
stores, but may not fit in your hood (they do make special ones
that have sockets for both flourescent day lights and moon lights).
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Maintaining the Crabitat
It's important to keep the crabitat clean for your crabs. I would
break crabitat maintenance into things that need to be done daily
(or every few days), weekly, and every few months.
Maintenance things I try to do every day or two include: refilling
the water dishes, checking to make sure heat and humidity are
at the right levels, emptying and refilling food dishes, and spot
cleaning for poo and spilled food. While dried food can be left
in the crabitat for up to a week if you suppliment it with fresh
foods, most fresh foods should really only be left in the tank
for about two days or they will begin to mold or stink. Exceptions
to this are probably flowers and dried fruits, which may be left
in a little longer.
Maintenance things I try to do at least weekly include: taking
the water dishes out of the crabitat and washing them thoroughly,
and washing and changing out the sponges I keep in the water dishes.
I have two sets of sponges per water dish, so each week I can
change them out and let the sponges dry entirely. This process
inhibits the growth of bacteria on the sponges.
Every few months, we do a deep clean. We remove all the crabs
that are above the surface to a temporary tank or holding area,
and then carefully go through the substrate for any crabs that
are buried. If we know we have molters under, we simply wait until
they come up unless it's a cleaning emergency (bugs or mold in
the crabitat), but crabs are frequently just digging under the
sand for fun.
Once the crabs are out of the way, we remove and clean up any
decorative items, climbing toys, and hidey huts in the tank, including
food and water dishes. We go through the sand and make sure there's
nothing in it and then bake it for a half an hour or so at 400°.
I always throw away any coconut fiber bedding in the crabitat
when we do a deep clean. It is cheap and easy to make more. While
the sand is cooling, we usually rinse out the tank and wipe things
out really well. Once the tank is dry and the sand is cool, we
start putting things together. We like to redecorate every time
we put things back in the crabitat, because then the crabs go
crazy exploring and re-staking out their territory and favorite
hiding spots.
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Entertaining and Exercising
Keeping your crabs entertained is easy - all they need are lots
of things to climb on and substrate they can dig in. Hermit crabs
may get lethargic if they are bored, so save room for some TOYS
(which often double as hiding spots, handily enough) in your crabitat.
They love to climb, so anything that will give them purchase will
entertain them. Driftwood, caves, coco-huts, cholla wood, silk
or plastic plants, even terra cotta pots will turn into climbing
toys for your hermit crabs. If something looks like it will not
give very good purchase, 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.
Crabs should be kept in a tank that is large enough to allow
them toys and space to move around and climb. If they are, they
do not need to be taken from their tank and exercised in any way.
Whether or not to handle hermit crabs is a relatively contraversial
topic in the crabbing community. On the one hand, people love
their crabs, and really want to be able to handle them and play
with them. On the other hand, you've spent lots of time making
the crabitat into the right environment for your crabs - is taking
them out of that environment and subjecting them to a cold, dry
house good for them, or does it cause stress?
For the most part, I fall into the hands-off camp. It's enough
fun to sit and watch them in their crabitat. For the most part
I think they're happier that way, and we've definitely had less
lost limbs since we stopped handling our crabs often. Occasionally,
we take them out of the crabitat for a photo-op, but otherwise,
we leave them in there unless we're cleaning.
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Molting
Crabs are invertebrates, which means they have a hard exoskeleton
on the outside of their body, and no bones inside their body.
Because the exoskeleton does not grow with the crabs, in order
to grow they need to shed their exoskeleton. Most of the time,
when they're getting ready to molt they'll stock up on food. Occasionally
you can see the food store on a pre-molt crab because they form
what is called a molt sac. You may also find them hanging out
in the water dishes more than usual, or notice that their color
seems a little pale or ashy. Those are also pre-molt signs.
Most of the time (and ideally) when a crab molts it will do it
underground (warning: do not dig up molting crabs if at all possible).
More often than not when our crabs are molting they'll burrow
all the way to the bottom of the tank and molt there. Most of
the time they spend "molting" is actually preparation
to shed the exoskeleton and time spent growing and hardening after
the exoskeleton is shed, the actual shedding of the exoskeleton
takes a few hours at most.
Occasionally, crabs will do what is called a top-side molt. These
tend to be more dangerous for the crab as they're more stressful
and also more exposed to any other crabs in the tank, who may
see them as food (especially if they're undernourished), or try
to steal the molting crab's exoskeleton.
Since only the front part of a hermit crab's body is covered
in exoskeleton, they don't have to leave their shells to molt.
When the crab is ready to molt, the exo cracks and the crab wriggles
backwards out of it. When they first shed their exoskeleton crabs
tend to be very pale and soft, they need a few days to harden
up and regain their color again. In order to harden their new
exoskeleton, they require lots of calcium, which they get largely
from eating the shed exoskeleton. They don't always eat the entire
thing, it's especially common for the BP and one or two of the
harder leg sections to be left untouched, but it is important
that they get those nutrients and are allowed the opportunity
to eat their exoskeleton. If another crab snatches it, or thinking
you had a dead crab, you'd already taken it away, offer other
calcium rich foods like cuttlebone, egg shells, ground oyster
shells, or shrimp with the exoskeleton still on it.
For information on isolating molting crabs, please see Isolation.
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Bathing
To bathe or not to bathe, that is the question. A few years ago,
conventional knowledge in the hermit crab world stated that you
must bathe your crabs every week or two in order to keep their
gills properly hydrated. However, this has become the point of
some controversy in the crabbing world.
Now it is generally considered better (and more natural) to provide
pools of water (both salt water and fresh water) that are large
enough for the crabs to submerge in rather than regularly taking
them out of their tank and submerging them. This way, they can
decide when they need a bath, and can regulate the concentration
of the salt water mixture they keep in their shells. While we
use pools made for reptiles, I have also heard of people using
narrow paint trays as a sloping pool to good effect.
If you have crabs that vary widely in size (we do!), the best
thing is to use something either to slope the pool so that a smaller
crab wouldn't have to go in the "deep end" or to place
something in the pool so a smaller crab won't have a problem climbing
out. In our tank, we have a sponge in each water dish, as well
as plants hanging into them that a crab could grab onto to pull
itself out.
If you cannot acquire pools large enough for your crabs to submerge
in, it is probably still a good idea to bathe them once in awhile,
though I would not recommend doing it more than once every two
weeks or so. These regular baths will serve to replenish and clean
their shell water and keep their gills moist.
To bathe a crab: Place the crab on its "back" in a
pool of lukewarm, dechlorinated (or distilled) water (not running
water). When it flips itself over, the water will rush into its
shell and sweep out any foodstuff or poo that is stuck in there.
Even if you don't regularly bathe your crabs, there are certain
situations where it may be a good idea. Please see Isolation.
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Isolation
Many hermit crab affectionados find it helpful to have a second,
small tank at the ready as an isolation tank. Normally there are
three reasons one might want to put a crab in an isolation tank
(iso): aggression, molting,
and new arrival.
Aggression in hermit crabs can be caused
by many things, but there are three really common causes for bullying.
The most common is probably the shell fight. One hermit crab
will decide that an already-occupied shell looks like the perfect
new home, and so tries to bully the current occupant into leaving
the shell. This bullying can manifest in many ways, including
turning the desired shell upside down and rocking it, poking legs
and claws into the shell to try to make the current occupant uncomfortable
enough to leave, and even trying to pull the current occupant
out of the shell forcibly. If this happens, it's best to separate
the crabs. If it continues, the agressor may have to be isolated
with a choice of new shells for a couple of days and placed back
in the main tank when he changes, or placed back in the main tank
(with supervision) after a few days with the hope that he's forgotten
about that perfect, but already occupied shell.
Another common cause of agression is a territory fight. I find
it's best to just let these play out in the main tank, but I do
know people who isolate bullies when they are caught fighting,
even if it's just for a few minutes. For this reason, when getting
new crabs its often a good idea to rearrange the tank so that
everyone has to stake out new territory at once, rather than having
one crab with no established territory trying to fight for a hiding
spot of his own.
The third and most worrying form of aggression seems to be caused
by a dietary imbalance. Hermit crabs, as scavengers, will seek
out the nutrients they most need in any form they can get them
- if the nutrients aren't provided, the crabs may become overly
aggressive, probably beginning to see their tank mates as a viable
food source. The best solution in this case is to separate the
bully in an iso, and start feeding fresh high protein foods (meat,
fish, poultry), especially sea food that is closely related to
land hermit crabs, like shrimp or crayfish, to both the crabs
in the main tank and the bully. This commonly alleviates the problem.
In a few days, try reintroducing your bully to the main tank (with
supervision) to see how it goes. You may also want to bathe your
crabs when you reintroduce one to the main tank. As a preventative,
it's a good idea to feed some sort of unprocessed, unseasoned
fresh meat, fish, or poultry at least once every week or two.
Some hermit crab owners choose to isolate crabs when they are
molting. This is done for a few reasons.
When a crab is molting, it is very soft and vulnerable, and another
crab may see it as food and attack it, especially if fresh fresh
protein isn't regularly offered. Other crabs may also steal a
molter's exoskeleton, which they need to eat in order to harden
up. As ominous and scary as that sounds, not everyone (myself
included) isolates molters. We've never had a problem with any
of our crabs being attacked during main tank molts - in fact until
a crab comes up looking freshly molted, or we notice he's been
missing for a month, peak under the tank and see exo, we often
don't even realize they are molting.
This is the real down side to the idea of isolating a molting
hermit crab - you have to be able to recognize the pre-molt signs,
be right, and catch them before they dig under. IT IS EXTREMELY
IMPORTANT NOT TO DIG UP MOLTERS IF AT ALL POSSIBLE.
If the idea of an unprotected main tank molt is just too scary
for you, there are certain ways you can isolate a molter within
your main tank. The pop bottle method seems to be the most common
- take a clean, empty pop bottle large enough so your crab fits
easily under it, cut off the bottom and take off the lid. Press
this down over the molting crab until it reaches the very bottom
of your tank so that other crabs can't climb under it to get to
your molter. If you don't have any pop bottles handy, you can
also use two CD cases to make a corral around your molter (press
them down to the bottom of the tank, so no one can dig underneath).
Since we generally just let ours molt where they dig, I've never
tried either of these methods.
The only time we isolate molters is if we accidentally dig one
up while we're cleaning our tank. In that case, we placed the
molter in an isolation tank with its exoskeleton, and put a coco-hut
over the crab to keep it nice and dark for him. Once he was up
and about again, we put him back in the tank with the rest of
the crabs.
Another time it's a good idea to isolate a crab is when you first
buy new hermit crabs. New crabs need time
to destress, especially if they're coming from a pet store that
keeps their crabs in poor conditions, and meeting a whole bunch
of new crabs may not be the most relaxing way to do that. New
crabs may also have health problems, most notably mites, which
you definitely want to avoid introducing to your main tank if
at all possible. If you decide not to isolate new crabs, it's
important to check very, very carefully for mites before putting
the crab in your tank. Mites are parasitic and very hard to get
rid of once they're entrenched in a nice warm, moist crabitat.
Once you're sure your new hermit crabs are healthy they can be
introduced to the main tank.
In order to keep the other crabs from being TOO interested in
a new or freshly molted crab that's being reintroduced to the
main crabitat, it is a good idea to either bathe all of your crabs
together so they all smell the same, or to bathe the new or freshly
molted crab in the tank water dish so it smells familiar to the
others. Because land hermit crabs are territorial animals, it
is also a good idea to rearrange the tank whenever introducing
(or reintroducing) a crab to your main crabitat.
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Shells
Hermit crabs wear shells to protect their soft abdomen, as well
as to carry water around with them so their gills can be kept
moist at all times. They want a shell that's light enough that
they can lift it, but not so light that it seems easily breakable.
It's really important to keep a variety of shells in your tank
to prevent shell fighting - generally, at least two or three per
crab either the same size as the shell they're wearing or slightly
larger. Some hermit crabs prefer an elongated shell opening, and
some prefer a round shell opening, so it's good to have a variety.
Paying attention to the shells your crabs are currently in is
one way of guessing which kind of shell they'll choose the next
time, but it's not a completely accurate indicator, since in the
wild shells are frequently chosen by availablilty, and your crab
may not have had a lot of choice.
Painted shells, which hermit crabs often come home from the store
in, are not recommended. Paint can be harmful if ingested by the
hermit crabs, and the suppliers to pet stores often use inhumane
means of making the crabs change from the shells they were found
in in the wild into painted shells. Occasionally shells are even
painted with the crab still in them causing the crab to become
stuck to the shell and unable to change to a larger shell as it
grows.
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