FAQs about Marine Crab Identification
7
Related Articles: Crabs, Hermit
Crabs,
Related FAQs: SW
Crab Identification 1, SW Crab ID
2, SW Crab ID 3, SW Crab ID 4, SW
Crab ID 6, Marine Invertebrate
identification, Marine Crabs
1, Marine Crabs
2, Marine Crabs 3,
Marine Crabs 4, SW Crab ID 5, SW
Crab ID 6, SW Crab ID 8,
SW Crab ID 9, Marine
Crab ID 10, Marine
Crab ID 11, Marine
Crab ID 12, SW Crab ID 13,
SW Crab ID 14, SW Crab ID 15, SW
Crab ID 16, SW Crab ID 17,
SW Crab ID 18,
SW Crab ID 19,
SW Crab ID 20,
SW Crab ID 21,
SW Crab ID
22,
& Crab Behavior, Marine Crab
Selection, Marine Crab
Compatibility, Marine Crab
Systems, Marine Crab
Feeding, Marine Crab
Reproduction, Marine Crab
Disease, Micro-Crustaceans,
Amphipods, Copepods, Mysids, Hermit
Crabs, Shrimps,
Cleaner
Shrimps, Banded Coral
Shrimp, Mantis
Shrimp, Anemone
Eating Shrimp, Crustacean Identification, Crustacean Selection, Crustacean Behavior, Crustacean Compatibility, Crustacean Systems, Crustacean Feeding, Crustacean Disease, Crustacean Reproduction,
|
|
Cool crab? Neale comes out of his FW shell!
6/10/07 Good morning crew. <Good morning. I'll take a
pass at this one with my marine zoology cap on, though I'm
sure Bob F or someone else will correct me if I'm
wrong...> Any idea what this crab is (see attached). <Not
at all clear from that photo. All I could see was an orange
blob.> At first, I thought it was an orange sponge but after
watching it for a while, I see that it crawls around my live rock
and grazes using some type of arms/mandibles. It's
tiny--maybe half a cm. I think it came in on some Florida aqua
cultured rock that I added. <Given your description and its
provenance, I'd suggest some Atlantic species of Schizophrys,
sometimes known as "Decorator Crabs". Of questionable
value in a reef tank given the fact these animals are fairly
omnivorous and can potentially catch and eat small fish, shrimps,
etc. They will also chop up things like sponges that they want to
use for decoration, as per their common name. Perhaps most fun in
a fish-only system with larger tankmates?> <Cheers,
Neale>
|
|
A "Guest" Arrived on my Live
Rock: Velvet Swimming Crab (Necora puber)
5/13/07 Hi Guys, <Hi Kim, Mich with you.> I just
wanted to start by saying your site has been a tremendous
resource! It has helped me many times. <Wonderful to
hear!> I have tried hard to find an answer to my
question without having to ask but I'm not having much
luck. I hope you might be able to help me out. <I will
try!> I purchased 75 lbs. of live rock recently and
after about a week I found a "visitor" I noticed a
rather large (aprox. 2 inches) crab hiding in one of the holes in the
rock. After many attempts of trying to identify this crab I
finally found out what he is. It is a velvet swimming
crab. <Necora puber> His bright red eyes were the
major give away on his ID. <Ahh, yes, also called the
Devil crab.> I can't seem to find much information on him other
than he is very aggressive and gets about 4 inches across. I
was wondering what your opinion is on him. Should I leave
him in the tank or find him another home? <I would not
keep this crab in a tropical marine setup. It is not a
tropical species. This crab is typically found in the North
East Atlantic, off the shore of the UK! I'm not quite
sure how it ended up in your live rock. This crab can pack a
pinch that could bring tears to your eyes, so please be
careful. Perhaps a nearby public aquarium could provide a
suitable home.> The tank he is in right now is a 72 bow-front FOWLER
set-up. Thanks for your time. <You're
welcome! Mich> Kim
Re: a "guest" arrived on my live rock
(Necora puber)?, update: now Eriphia sebana. -- 5/13/07 I
must apologize, <No worries.> I just got a call from my LFS and
they think they may have found out that he is NOT a velvet swimming
crab. <Ahh, the initial ID did not make much sense, as Necora puber
is a cool water species, but stranger things have happened.> After
doing their research they now believe it might be Eriphia sebana.
<This would be more logical.> We have been working for over a
month to ID this guy. <Could have sent a photo here.>
Which from what little bit of information I can find on him makes more
sense being that they are from Fiji. <Yes, along with
Australia, the Maldives...> Could you tell me a bit about Eriphia
sebana? <Will try. Hmm, it seems I'm on a
toxicology run. What ever you do, don't eat this crab!
Ingestion can result in PSP Paralytic Shellfish Poisoning and I suspect
this potential for toxicity could also cause problems if the crab were
to die in you main system.> Should I leave him in or remove
him. <I would keep him isolated.> I do have an empty
10 gal. with live rock already set up and cycled for a hospital
tank....could I keep him in there? <I think this would
be wise.> If so...what should I feed him. <Most crabs
aren't too finicky. I would offer a
variety. Reportedly this crab eats algae during the day and
relies on predation for midnight snacks!> I'd hate to get rid of
him, he is very neat to watch at night. <Watch, learn and
enjoy! But be aware he can be an aggressive crab so between
the aggression and the toxic potential, you may need to keep this a
species tank.> Thanks again for all your help,
<Welcome! Mich> Kim
Crab Question, ID Likely a Boxer Crab (Lybia
tesselata) 5/13/07 <Hi Jason, Mich here.> I have
seen a crab in my tank and it looks like it has feather duster tips for
arms and he waves them at his mouth like he is eating stuff. <The
"feather dusters" you refer to are likely small anemones in a
mutually symbiotic relationship with a Boxer or Pom pom crab.> He
has small claws too. Do you know what kind it is? It is maybe a quarter
inch in size. <Sounds like a Boxer Crab (Lybia tesselata). A picture
here: http://www.wetwebmedia.com/marine/inverts/arthropoda/crabs/swcrabs.htm
and more on Google images. They are generally reef safe, can
be fed minced meaty foods and should not be kept with aggressive
tankmates. A delightful little addition! Do
enjoy!> Thanks for your time.
<Welcome! My pleasure to assist. Mich>
Jason
Mystery Crab ID - 04/22/07 My reef tank has been up and
running for about a year and a half now and this morning when I
saw the tank there was a huge purple crab on the side of my clam
that I have never seen before. <<I see it>> I
searched on Google and a few other sites and can't seem to
find any info. If you know what it is and if it's
reef safe I would really appreciate it. Thanks - John
<<Well John, this may be a box crab, of which there are
about 40 different species I think...and no, I wouldn't
consider it to be "reef safe." EricR>>
Re: Mystery Crab ID - 04/23/07 <Bob, where
did you put the ID pc?> Thanks I appreciate it.
<<Welcome>> Yeah, I woke up this morning and saw him
eating the side of one of my clams!! <<Yikes...time for
this crab to go!>> Any advice on catching him? <<Mmm,
can be difficult...try sinking a small glass jar in to the
substrate or among the rockwork, and place a small piece of meaty
food in it (table shrimp does fine). If you can entice
the crab to enter the jar (may need to leave in place
overnight...may take several attempts), you "should" be
able to reach in and cover the top/remove the jar before the crab
can scale the slick glass walls. Regards,
EricR>> R2: Mystery Crab ID - 04/23/07 Thanks a lot,
I'll give it a try tonight. -John
<<Good Hunting! EricR>>
|
|
Crab ID (Can't Tell From the Pic) --
04/02/07 Hi guys, <<Howdy Patsy>> Love your site!
<<Always nice to hear...thank you>> I can't seem to
find any ID info on the crab I recently discovered living in my
LR. I purchased the LR from Tonga and have had it since
May of 2006. The crab is about 3/4 of an inch wide, purple/pink in
color with a large white strip on its back. It
doesn't like to come out of the rocks. <<A shy one,
eh?>> The left claw is larger, I assume it's
male. I have attached a picture, not very clear, but all
I have. He moves to fast! <<Mmm...can't
discern much from the picture I'm afraid>> Is he harmful
to other inhabitants in the tank? <<An opportunistic
omnivore...a good chance it is harmful in some way, yes>>
I.e. Snails, cleaner shrimp, or other hermit crabs?
<<Possibly...especially if it gets larger>> Anything
you can tell me would be helpful. Patsy <<I am not a fan of
crabs in reef systems as I feel they are too predatory and
opportunistic in their feeding habits. I can't say
what species this crab is, but trapping/removing it is the only
safe option in my opinion...the decision is
yours. Regards, EricR>> |
Purple Crab ID - re-sent... 4/11/07 Hi, Patsy here.
<Hi Patsy, Lynn here> I found a crab in my LR from Tonga
and I am unable to find an ID for it. <Understandable - very
difficult indeed.> I have just discovered him and have had my
tank for a year. <Not surprising - many are shy, nocturnal,
and very good at hiding/camouflage (especially when small!)>
It just molted and is purple in color with a large white strip
down its back. <Pretty!> It has large front legs. I have a
picture but it is blurry and hard to see. <I see those big
claws!> The crab lives in the rock and does not like coming
out. I see its claw occasionally picking at the algae growing on
the rock. I hope you can help. <Unfortunately, crabs are very
difficult to ID to specie level but the main issue is that most
are not reef safe. They're opportunistic and omnivorous, so
although yours may not pose a threat at its current size,
it's very likely to do so as it grows larger. My
recommendation would be that unless it's alone in your tank
(no fish/corals) then I'd remove it, or at the very least,
keep an eye on it and its tankmates. Please see these links for
more information and good luck! http://www.wetwebmedia.com/swcrabidfaq3.htm http://www.reefkeeping.com/issues/2003-12/rs/index.php
> Thanks Patsy <You're very welcome!> PS: Love your
site!<Thank you very much indeed! -Lynn>
|
|
Emerald Crab ID?? 3/11/07 Hey guys,
<Brian> I went to a LFS to buy an Emerald Crab about 2 months
ago, when I got there they were all tan/beige colour. The LFS said that
it was because of the algae they were eating in the tanks. <Mmm,
could be, I had a pizza last night and this morning I was
yellow. Do not believe this is the case.> I bought him
anyways, my last Emerald Crab was bright green so I figured the new one
would turn green eventually. He just molted today and now is gigantic
compared to the original size, but still hasn't turned green. Do
you think that maybe they pulled the wool over my eyes and that its not
an emerald crab? It looks the exact same as my last green one, same
carapace, same hairy legs, same claws but he's just beige instead.
What do you guys think? <I'm not aware of any beige Emerald
Crabs, the name certainly implies the color. Bob?>
<<Not all are green, nor stay green. "Follow the Yellow
Brick Road"... B>> Thanks <Brian, in future queries, do
cap beginnings of sentences, proper nouns, and
"I's". We just do not have the time to correct
text before posting on the dailies. James (Salty Dog)>
Brian
Crabs in my reef? Yes a Coral Crab
(Trapezia ferruginea) 3/10/07 Hello Again Bob, <Hi
Brian, Mich here tonight!> I found some crabs hanging out in a
couple of my Acropora corals last night. I have pulled them out of
the reef, but still have no clue what kind of crab they are. There
are 3 photos below if you could tell me what you think they are it
would be greatly appreciated. <This looks like a Coral Crab
(Trapezia ferruginea). They are reef safe and eat mucus
off their host coral. They usually hitchhike on stony
corals and are typically hardy when provided a host, which is
usually a Pocillopora spp. or a Stylophora spp. If you
want them to live, and you should, they need to be returned to
their respective corals.> <Welcome! -Mich>
Brian
|
|
Crab I.D. Emerald crab (Mithrax
sculptus) 3/9/07 Thanks for a great website, it's a
wealth of information! <Thank you for you kind
words. Glad you find it useful!> My question for you
is this: This crab came in on my Bubble Coral and I'm just
wondering what kind it is? and, is it safe to keep it in my reef
tank? <Well you appear to have a inherited an Emerald crab
(Mithrax sculptus). They are generally considered reef
safe herbivores in so much as any crab can be truly called
this. But there are a few reports of this species
attacking sessile animals. Is generally OK with an
occasional bad egg. Is one of the few creatures that
will eat bubble algae (Valonia). More here and links in
blue: http://www.wetwebmedia.com/mithraxfaqs.htm Thank you very
much, <You're welcome very much! -Mich>
Steve |
|
Can you tell me what crab this is:
2/20/07 Sincerely, Marty Dick <Mmm, nope... other than to
agree with you that this is a Decapod, crab. BobF> |
|
Crab ID, please help 2/13/07 Here
are two photos of a little hitchhiker crab that I chased around my
display tank for the better part of eight months until I caught him
and banished him to the sump of my prop tank. :) <Is a
beauty!> I talked to a lot of people who ID'ed him (without
a photo) as being a gorilla crab because of the bristles on his
legs and the black pincers. <Mmm, well is very likely a Xanthid
("Dark fingered crab" family Xanthidae) member...>
However, to me, he looks more like a Emerald Crab on steroids. They
also have the same bristles on their legs, <Bristles are not a
useful identifying characteristic here> and they also have very
similar markings on their carapace. A lot of people have said that
the black, sharper pincers are a giveaway for a meat eater, but
I'm just not so sure. <Is so for the family, yes...>
These are photos I took about a month ago when I finally caught it.
One guy from my club said it was likely a "Mithraculus
forceps" and quoted page 149 of the sprung invertebrates book,
<Nah> which of course - I do not own. He claims it this is a
brown version of a emerald crab and prefers green algae for food.
<Negative... wrong...> I'd like to put him back in my
main tank because I need some more scavengers in there, and why pay
for something I already own... <Uhh... is decidedly more of an
eater upper than cleaner upper> But I don't want to
potentially endanger any of my small fish or other livestock based
on a bad ID. Please let me know what you think before I let him
loose on my hair algae. <Won't be eating much of this>
FWIW, if this guy *is* reef and fish safe and is "Mithraculus
forceps" I would order more of this species any day over the
emerald crabs. They have much more "personality," are
much more animated, and seem to be a nice little crab. I will
anxiously await your response. JW <Well... if you want to
(continue) to feed this "meat eater" in your main system
and tolerate some "picking"... this is up to you. I would
keep this animal... but likely in a sump, where it would do little
harm. Bob Fenner> |
|
Re: Crab ID, please help 2/13/07
> <Well... if you want to (continue) to feed this "meat
eater" in your main system and tolerate some
"picking"... this is up to you. I would keep this
animal... but likely in a sump, where it would do little harm. Bob
Fenner> Follow-up question... Could you please define
"picking" <Sure... lightly sampling to eating (to
death) what it can get hold of> Is he a risk for my other
animals?? Might he sneak up on a small goby and have his way with
them? <Yes... is possible> I'm not sure I completely
understand what risks he might pose. <Such decapods... small to
larger... are opportunistic omnivores. Understanzee? BobF> |
Re: Crab ID, please help 2/13/07
Thanks for the reply, Bob. Not what I wanted to hear, but
that's the way it goes. Thanks again. <Welcome my friend.
BobF> |
Re: Crab ID, please help [3]
2/13/07 Yep. We is clear. <Ah good> Thanks again for the
service you provide. <Welcome> Thanks to your website and
your books, you have empowered me to create a sumpless 29 gallon
aquarium that looks like this... <Ahh, a pleasure>
Unfortunately my wife and I just had a 10 week premature baby that
needed a couple surgeries to get things right, so it looks like my
volume won't be increasing any time soon. JW <A shame for
the young to endure such. Life to you my friend. BobF> |
Crab identification 1/19/07 Dear WWM,
<Greetings.> First, I'd like to thank you for your
awesome database of knowledge about Reefkeeping... <Welcome. You
might say, we're here for you...> I found almost anything I
was wondering about in your pages... well, except for my little
problem: I have this crab (see pic) in my tank since the beginning
of it, 7 months ago. It has shown no harm for the moment, he's
just hanging out in his cave, sometimes with part of its legs out
to fish some food when it's meal time. Whether it's 10am,
10pm, 3am, he's always in his cave, never caught him out
wandering... When he's half out of cave, if a fish comes by, he
immediately rush into his home. He's hairy, light tan skin with
dark red irregular spots/stains, neon green eyes, darker brown
tipped pointy claws, maybe an inch large for its back (not with the
legs). Actually, my problem is everybody is telling me to kill him,
but I first I never killed an animal and I'm very reluctant to
do so, and then I don't want to kill an animal just because he
might be a predator, but with no certainty. <It' up to you
what you do with your aquarium, but the rule of thumb I used to use
with crabs when I was in retail was: "If it's hairy,
it's not beneficial". We also have a saying here at WWM,
"When in doubt, take it out". Now, that doesn't mean
it can't be a good pet, but it may end up predating a prize
fisherino sooner or later.> So I'd like to know FOR SURE
whether he might be a threat to my fishes (and I'll be forced
to kill him, because I have no sump nor refugium), or if he'll
still be small and shy all his life long (and I'll consider him
as a friendly part of the population). Can you tell me the exact
species, and how tall he'll be as an adult? <Let's give
a look...mmm, no I don't have a Latin name for you here, but I
will forward to BobF for possible positive ID. I was thinking about
a Pumilus crab, I saw a photo once, it looked quite similar, but
couldn't find any info on the net about this specie...
<Ditto...> kind regards, and best success for 2007! <I
would check the crab ID FAQs here on WWM ( http://www.wetwebmedia.com/swcrabidfaqs.htm ) Thanks for
the -Graham T.
Sabine |
|
Red hairy crab sorry sent with out
picks 1/12/06 HI, <Hello there> First I just
want to say thanks for all of the help! <Welcome> I am coming
up on one year with my first saltwater tank and you guys have saved
it many times. <We have helped you save it> I have a 95
gallon with about 85lbs of live rock and many fish and corals. I
have a red crab that has hitchhiked into the tank on
LR. I think he may have been nibbling on my Yellow Fiji
Leather but I am not sure. He was hiding under it for a
while and it was not opening all the way. Otherwise I
have only seen him eating off of the LR. Are you
familiar with this red crab, is he reef safe, and should I keep him
or get rid of him? <Nice images... I don't know what this
crab is... but I would keep it isolated from your main reef
livestock...> See attached pictures. I was able to
catch him after about a month of trying so that I could quarantine
and take pictures. I do not want to kill him if it is
not necessary. However I have grown a very diverse
environment of small organisms and do not want them wiped out nor
do I want anything eating on my corals. <I understand> Thank
you, for any assistance that you can provide. Bryan E Stone
<Perhaps in a sump... Bob Fenner> |
|
|
|