FAQs on Freshwater, Terrestrial Crab Behavior
Related Articles:
Fresh to Brackish Crabs,
Freshwater Crustaceans,
Invertebrates for Freshwater Aquariums by Neale Monks,
Forget Crawfish Pie, Let's Make a Crawfish Tank! By Gage Harford
Related FAQs:
Freshwater Crabs 1,
Freshwater Crabs 2, &FAQs on:
FW Crab Identification,
FW Crab Compatibility,
FW Crab Selection,
FW Crab Systems,
FW Crab Feeding,
FW Crab Disease,
FW Crab Reproduction, &
Fresh to
Brackish Water Crabs,
FW Crustaceans 1,
FW Crustaceans 2,
Terrestrial Hermit Crabs, &Marine:
Hermit ID,
Hermit Behavior, Hermit Compatibility, Hermit Selection, Hermit Systems, Hermit Feeding, Hermit Reproduction, Hermit Disease/Health, &
Crayfish FAQs,
Crayfish 2,
Crayfish ID,
Crayfish Behavior, Crayfish Compatibility, Crayfish Selection, Crayfish Systems, Crayfish Feeding, Crayfish Disease, Crayfish Reproduction,
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Re: Mr. Crabby – 8/29/13
Neale,
<Jennifer,>
<<excerpted>>
Anyway, no new crabby news from me right now. Mr. Crabby is still
waving his big claw around to no one in particular and doing his crabby
man dance all over the tank. The girls are paying no mind to him.
The tank is due for another cleaning - Yay! They will be happy but
I am not looking forward to the four hours it takes....At least I have
it down to a pattern now of what to do. Most likely I'll give them
some krill this afternoon before I clean their tank this evening.
I usually like to give them some good stinky food for a nice feeding
before I clean......
<Indeed.>
My friend with the hermit crab is figuring things out regarding
sand....lol. He said it got too wet and started stinking, which I told
him it would! He had to buy new sand and he bought some other type
of bedding/substrate. He also has a crawling wall along the back
and apparently they like to crawl up it and up to the screen top.
They also got an additional hermit crab and within a day of being
brought home from the pet store, he changed shells....haha. I know
I asked you about iodine for them - where should they add it or how
should they give it to the hermit crabs?
<Add to the bathing water.>
It's easy with the Fiddlers to add it to the tank water, but I wasn't
sure how to tell them to give it to their hermit crabs...especially
since the bottle says to give such a small amount/gallon. I know
they have a salt water dish (they buy the bottled salt water) and a
fresh water dish....but is that too small of an amount of water to put
the iodine?
<Possibly; if it's easiest you could mix with tap water in a large empty
soda bottle (a couple litres here in England) and then store and use as
required. Somewhere cool and dark, but need not be refrigerated. You can
then decant as much as you need.>
Thanks for your advice for me and for my friend now too!!! I know
he said he appreciates it because he didn't realize what a learning
curve there was for hermit crabs!!! He also said he was shocked to
find out they could live for 15 years or more.....haha. I thought
that was funny. I keep laughing at him because it all started with
his little girl wanting to win a crab at the carnival. As you
mentioned, we used to have carnivals with goldfish and when I was little
we won a little goldfish. Of course that turned into us buying two
more goldfish as friends for him....and it turned into a ten gallon tank
and them living for over ten years!!! So, I know how that goes
with a carnival "win" turning into a costly long-term investment.
<Ah, yes, a common "problem" with animal visitors. On the other hand,
the rewards of animal ownership are many, especially for families with
children -- patience, responsibility, passing of time and resulting
growth, death, birth of next generation... so much easier to explain
these things to children when they can experience it through their
animals.>
Well, I am sure you'll be hearing from me again as I know I'll have
questions. For now, I think I am good.....lol.
Jennifer
<Real good! Have fun with the various animals in your care, Neale.>
Red Claw Crab Missing Limbs 10/12/10
I purchased 2 Red Claw Crabs from PetSmart.
<Perisesarma bidens and interesting, if aggressive, brackish water
crab.>
I believe one was male and one was female, do to the markings on their
underbellies, plus one had slim claws, and the other had fat, wide
claws.
<Do bear in mind males and females view each other as food except
when mating!>
After about a month, one crab (female) molted. She was seemingly fine
after the molt, with all appendages in tact. Two days later, 2 legs and
both front claws were missing. I removed the other crab (male),
assuming he attacked her. Three days later, the attacked crab died.
<As often happens.>
Am I correct in assuming the other crab attacked her?
<Possibly. When crabs moult they would normally hide in places such
as caves or bury themselves in leaf litter. Either way they'd be
out of view. Crabs view one another as potential meals, and in their
"soft" state they're easy targets. A lot depends on their
environment, and in a spacious tank with plenty of hiding places crabs
can moult successfully. But if you crab two crabs in 5 or 10 gallon
tank, it's hard for them to avoid each other, and if there
aren't any good hiding places, and I mean REALLY good hiding
places, not some upturned flowerpot, then they can, will attack one
another.>
Did the molt have anything to do with what happened here?
<Can certainly be a factor. But bear in mind lack of iodine is a
very common reason for failed moulting. Use marine aquarium iodine
supplement at 50% the quoted dose per gallon of water. Also make sure
their diet is calcium-rich -- a mix of whole lancefish, unshelled
shrimp, and suitable soft fruits should do the trick, along with
regular offerings of crustaceans foods such as those from JBL, Sera,
and others.>
Would the lost appendages result in her death?
<Not in themselves, no, but lack of iodine can cause various
problems, deformed appendages merely being the most obvious
symptom.>
Also, I've read on your site that RCC are land crabs, but mine
stayed in the water most of the time.
<Well, they are land animals. In the wild they live in estuaries,
dipping into brackish or salt water periodically but foraging on land.
On the other hand, for a variety of reasons they may prefer to stay
underwater in a given aquarium, perhaps because there's only enough
dry land for one dominant individual. Cold and dry air can also stress
them.>
My tank set-up: 10 gallon tank, part land, part water. Sea salt mixture
added to water,
<How much? You really need brackish water, not "teaspoon per
gallon" amounts of salt. Use marine aquarium salt at not less than
6 grammes per litre (~3.8 US gallons), and ideally 9 grammes/litre, for
a specific gravity of at least 1.003 and ideally 1.005 or more at 25
C.>
with calcium and other trace elements especially for invertebrates.
<Iodine is the key, and yes, you do need iodine supplement.>
Utilized a terrarium filter to clean the water. Fed spirulina flakes,
bloodworms, krill, and crab pellets. No heater was used in the
water.
<Well, that's one problem. They are tropical animals. The air
needs to warm and moist. Essentially you're creating a habitat
similar to what you would for tree frogs, except the bathing pool
contains brackish rather than fresh water. Apart from that, the coconut
fibre substrate will be similar, and the bogwood and plastic climbing
branches will be similar.>
After this experience, I do not believe PetSmart should be selling
these crabs.
<Difficult to argue against. But they are bizarre animals, and some
dedicated individuals have even bred them! The larvae need to be moved
into seawater conditions and fed tiny live foods, but it is
possible.>
They seem to be aggressive towards one another,
<As are virtually all crabs.>
and their requirements go way beyond what the pet store would have you
believe.
<Same with Goldfish, to be honest.>
I wouldn't recommend them as a pet for the average person.
<The huge problem is that the "average person" doesn't
usually keep pet animals terribly well. How many dogs do you know that
get short, infrequent walks? How many parrots do you know living in
small cages? How many Goldfish do you know get in bowls or small
aquaria? You and I are different in caring about how animals are
maintained in the home; the average person often doesn't care all
that much -- or perhaps more charitably, doesn't understand how
badly they're treating their pets.>
Thank you for any information you can give! Your website is
awesome!
<Kind of you to say so.>
Lorie Masi
<Cheers, Neale.>
my crab... F, really
BW... color change... beh. 06/12/09
Dear Crew;
I have a red clawed crab that I have had for almost 6
months now. He always seems pretty happy and forages around a lot for
food. I feed him shrimp pellets and the odd tiny piece of orange (which
he attacks and drags into his cave to devour). Today I looked at him
and he has suddenly gone really red. I mean really red: his legs, his
chest, and even some of his back. The little guy has molted twice now
and I don't remember the colour change. He seems really active, the
water is clean, I don't know if something is
really wrong, or really right. Can you help me?
Thanks!
Rachel
<Hi Rachel. It's difficult to know whether or not what
you're seeing is normal, and the best approach with crustaceans
generally is to focus on preventative healthcare. We know precisely
what Perisesarma bidens needs to do well: an aquarium with dry land to
explore; marine aquarium iodine added at half the normal dose; and
brackish rather than freshwater conditions, 6 to 9 grammes of marine
salt mix per litre of water being adequate. If you do all these things,
your crab should be in good health. If you're not doing all of
these things, then it's possible you're seeing some sort of
negative reaction. If he's active, that's a good sign, so if
you correct conditions in the tank, hopefully he'll settle down and
have a healthy life. Cheers, Neale.>
Re: unknown crab,
fdg., sys., beh. 4/22/09
Neale,
I was mistaken when I said that the crab had eaten a nice piece of
cantaloupe.
<Banana! Land crabs seem to love banana, the softer the better! Also
try small pieces of white fish, ideally lancefish, which you can buy in
pet shops. These have bones in them, and the calcium there is excellent
for the crabs. Unshelled prawns, perhaps sliced along the middle to
make things easier, are also a good source of calcium. Crabs are
scavengers, and generally eat anything that's soft or
meaty.>
My wife had removed it as it was getting a bit smelly. The crab has not
eaten anything since we got her and has seemingly become very weak.
<Review air temperature and humidity; these are essentially like
frogs in terms of care, and cold, dry air does them no good at all.
Turning the heater up in the water side of the tank can create more
warm, humid
conditions in the land side of the tank. Likewise, keeping the lid more
firmly secured will help, too.>
She has not moved much in the past 2 days. Maybe she's getting
ready to molt.
<You can actually check this: before they moult, crustaceans absorb
extra water. When picked up, you may notice they've both bulked up
and yet the shell is softer than normal, and may even yield a bit to
the touch. They feel less heavy for their size that you'd expect (a
tip you using when buying edible crabs, by the way). While the
following link refers to Land Hermits, in terms of generalities, it
would hold true for Land Crabs too:
http://hermit-crabs.com/molting.html
So, prior to moulting, the crab will puff up, become softer, tend to
hide away from light, and generally become inactive. Moulting starts
with the exoskeleton unzipping, and the crab sort of backs out of its
shell,
tail-end first.>
I hope so. We would not feel like very good stewards if she dies.
<I understand!>
Already lost one pet this week :-( One of our Fischer's lovebirds
had a seizure and died in my hands.
<Oh, sorry to hear that.>
Of course, I have zero history on the crab. Have tried feeding her a
variety of foods to no avail. Any suggestions? Thanks.
Quick
<Cheers, Neale.>
Odd freshwater Crab
behaviour I have a ten gallon tank with low water and rocks for
crabs and other crustaceans. I bought some crabs and here's my
q's. One: Are the crabs with one large and one small
claw males, and the ones with two small claws females? Two:
Today the male??, one large one small claw, climbed out of the water
onto the rock and started foaming? or bubbling from his face and doing
something, like he was washing?? what is this? He the proceeded to sit
then later he did this crazy claw dance, waving his arms around slowly
in these rhythmic motions all the way out and then back in, what the
heck? Does he have mad crab disease? Three: I put in feeder golds but
they seem to ignore them. so I feed blood worms. should I add plants
for veg food, or just stay with blood worms and whatnot? Four: The red
crab I got has only one claw will his other grow back like at molting
or something? Five: What's the ratio on crabs? The same as fish or?
i tried here and all over to find good info on their behaviour and i
came up empty handed! >> Yes, crabs with one larger claw are more
likely males in most species. Crabs have to get oxygen when they are
out of the water they will "chew" a small amount of water to
mix it with air and get oxygen from this process, that is likely why
your crab is foaming. He is waving his claws to show his territory and
attract females, so he is not mad. You can feed with bloodworm, but try
other foods to see what else your crabs will eat, it varies from one
species to another, but most are omnivores. The missing claw should be
replaced in the next molt, I would not worry. For a great
website on crabs and other crustaceans check http://www.crusta10.de
not sure if it is all in English, but the site owner is one of the most
knowledgeable people on the subject. Good Luck, Oliver
Anomalous
Crab Question - 10/30/2004 Hello, My little red crabs keep getting
on the filter and just sit there like they are in a stream. <Er, do
you know what kind of crabs these are? Can you give me a
good description of them? Size, coloration, markings,
anything like that?> I do not see how they are getting up there
unless they can swim. Why and how do you think that they are doing
this? <The how is the easy part. Crabs are *amazing* for
being able to climb nearly anything.... I wouldn't be
too terribly shocked if they were simply climbing the
glass! But more likely, they're finding a way up to the
filter intake tube, and climbing that. Now, as for the
"why" of it, there are likely a few
reasons. First, is this a fresh, brackish, or saltwater
aquarium? In what country do you live? In the US,
there are nearly - or absolutely - no crabs sold in the hobby that are
truly freshwater animals. Most will survive in freshwater
for a time, but they will not thrive and will not live their full life
span. Moreover, nearly - or absolutely - no crabs sold in
the trade in the US are truly aquatic. All are amphibious,
or land crabs that only occasionally venture into the
water. Chances are, your little inverts are just trying to
find a way out of the water. At the very, very least, I
recommend you drop the water level a bit, and give them a surface to
rest on out of the water. Try to provide them with a few
hidey-holes on the surface to help them feel
secure. Remember, crabs are extremely adept escape artists,
and they can and will find any way out of the tank, especially if
they're not happy with their setup. Please be sure you
have a tight-fitting lid, or you might wake up in the morning to find a
crab cuddling you in bed! ;) > Thank you Kayce
<Wishing you well, -Sabrina>
Molted Crab - 05/31/2004 I have
a Red Claw Crab, he is my first crab and I don't know what to do
now that he has molted. His old shell/skin is sitting at the bottom of
my tank, I don't know if I should remove the skin or leave it in
the tank. <I would leave it.><<Often are eaten,
reincorporated into new exoskeletons... necessary mineral content.
RMF>> I know Hermit crabs need their old skin to eat, but I
don't know what to do with this one. <If it's not gone in a
few days, pull it out. I would assume the crab (or other
denizens of the tank) will have made short work of it, by then, but if
not, best to get it out. Wishing you and your crab
well, -Sabrina> Shelly
Warren