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FAQs about Marine Crab Identification 12
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 Crab ID 7,
Marine Crab ID 8,
Marine
Crab ID 9, Marine Crab ID 10,
Marine Crab ID 11, &
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
7, SW Crab ID 8,
SW Crab ID 9,
Marine Crab ID 10,
Marine Crab ID 11,
&
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,
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Interesting Crab Found in My Lunch: Oyster Crab - 11/15/08
Hey Crew.
<Hi Andy>
I bought some Blue Point Oysters today and, upon
opening one up, found the attached crab in the oyster.
<Neat>
I've seen
these before, but this one was alive. I took a few shots of it and thought I'd
share. I have no idea what kind of crab it is, but I thought it was interesting.
Blue Points are from the Long Island Sound in New York. Enjoy.
<Thanks! It's
very likely Pinnotheres ostreum, a type of pea crab, sometimes called an oyster
crab. They're commensals that live in the mantle cavity of bivalves and are
supposedly brownish-green in color, although they turn red when cooked (like
lobsters and other crustaceans). Please Google the above scientific name and/or
�oyster crab� for more information regarding these neat little creatures:
http://wetwebmedia.com/Googlesearch.htm >
Andy
<Take care, Lynn>
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Re:
Interesting Crab Found in My Lunch: Oyster Crab - 11/17/08
Thanks, Lynn.
<It was a pleasure, Andy.>
Yep, from my searches, it
does appear to be a Pea Crab. Looked exactly like the picture here:
http://www.dnr.sc.gov/marine/sertc/images/photo%20gallery/Zaops%20ostreum%20in%20oyster.jpg
<Yes, they're odd but at the same time neat looking little creatures. By
the way, I was looking around for more information today on this crab
and found that the species name I gave you (Pinnotheres ostreum) has
been reclassified as Zaops ostreum. Pinnotheres is considered a synonym
but Zaops is the currently accepted genus.>
Not that it matters, but
I noticed that when you posted my query on WWM, the pictures weren't
attached.
<Yes, and I apologize for that. I'm not sure what
happened.>
Take care, and thanks again/as always.
Andy
<You're
very welcome. Take care, Lynn> |
Weird flat spider thing
10/17/08
Guys, the information on this site is outstanding. My uncle was a Nat Geo marine
photographer, and he seems to of passed the fascination on to me. I trolled your
site but can't find what I'm looking for. Hope you can give me some clues to
research
<OK.>
I just got home and the light timer hadn't been
working...... which is another story. I got some awesome live rock from
Queensland with a huge amount of life forms in it. All sorts of worms, crabs,
tiny star fish, different slugs, crazy looking fungus and sponges, things that
squirt stuff.... too much to mention. Anyway, enough boasting. I turned the
lights on and there was this huge dark coloured flat creature with a centre
piece, maybe 1.5inch to 2inch with between 6 - 8 hairy legs coming from the
centre, that got thinner towards the ends. I guess the total diameter of the
creature was about 6 - 8inch. It's ran away quickly a bit like an Octopus might.
<Hmm... without a photo, obviously difficult to out a name to this.>
Any
ideas?
<Do review the genus Percnon, particularly Percnon gibbesi, a very
common "stowaway" in reef tanks. It's very flattened, has long legs, and up to a
point is amphibious. It's an invasive species, and has recently appeared in the
Mediterranean.>
Many thanks
<Cheers, Neale.>
Mystery coralline-eating crab –
10/10/08
Hi there!
<Howsit Juli?>
Thanks for working to educate us newbies!
We have had a 50 gallon saltwater aquarium set up for about 6 months now with
live sand, live rock, 2 ocellaris clowns, a Longnose Hawkfish, and a royal
gramma Basslet. We also added an assortment of hermit crabs, snails, and a
cleaner shrimp before realizing that the crabs were probably not the best idea.
<Surprised the Hawk has not consumed most all the crustaceans here>
However, the ones we purchased (red-legged, dwarf yellow tip, dwarf blue leg)
are small and do not seem to be causing issues as of yet. Our last purchase a
couple months ago were two pieces of live rock with mushroom corals attached...
and apparently, a "cling on"... while looking after the lights went out one
night, we discovered a small (maybe 1/2 inch?) hairy crab lurking under one of
the rocks! I searched the site and found an obscure reference to one bearing
similarities (http://photos1.blogger.com/photoInclude/hello/252/1727/640/DeadCrab.jpg)
but it's not an exact match.
<Mmm, the shape overall, the darkened tips of the claws... a member of the
family Xanthidae... Mud crab/s... predaceous>
Over several nights, I observed this crab moving sand
around underneath the mushroom rock and several adjacent ones and it only
appears to be eating coralline algae.
<Mmm, and likely more>
I have witnessed this behavior, where it breaks a chunk of rock off with one of
its claws (they are the same size) and sends grains of rock flying. The carapace
itself appears to be purplish coralline in color and the legs are whitish, bumpy
and fuzzy.
<Beautiful. Good description>
Its eye stalks are black and so far, the thing is only active after the lights
go out. Sorry I couldn't get a pic, this little guy is definitely camera shy. If
you can give any ideas or direction, we would greatly appreciate your help!
<Mmm, nothing more than a cursive review of our Crab ID FAQs:
http://www.wetwebmedia.com/swcrabidfaqs.htm
and the many in the series linked above... This one... not a worry/problem until
it's eating, destroying too much... at which point, you might want to bait/trap
and remove it to elsewhere. Bob Fenner>
Re: Mystery coralline-eating crab
10/11/08
Bob,
Thanks so much! After searching under Xanthidae/mud crab, I most definitely
think it's in that family. We are planning to upgrade to a 120 gallon tank in
the next few months, so will be perfect timing to remove this guy and send him
back to the LFS.
Regards,
Juli
<Ah good. Cheers, BobF>
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Hitchhiker Crab ID: Need More
Information – 10/8/08
Hello,
<Hi there!>
I wondered if you could identify this crab?
<I hope so! That's an interesting little crab you’ve got there. Is there any way
you could get a photo showing the entire top of the crab/carapace and all legs
(as detailed as possible)? I need a bit more information to help narrow down the
possibilities. Also, do you know where the crab came from?>
Thank you in advance~
<You’re very welcome. –Lynn>
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Re:
Hitchhiker Crab ID: Need More Information – 10/8/08
<Hello again>
No sorry, that's the most I have ever seen of him.
<Well, I can sure understand. I have a crab that likes to play hide and
seek with me as well. I know what species it is, but I’ve never been
able to get a good photo of it. Your success is a testament to your
patience and skills with a camera!>
He usually just sticks the smaller of the two arms out and picks stuff
of the rocks.
<Yep, it’s one of those “form follows function” things. That’s a perfect
little claw for delicate picking. The other claw looks capable of taking
on larger items, or it could be mainly used in defense/dominance
displays, attracting a mate, or a combination of all of the above. I
just don’t know.>
I will try to take some more pictures tonight.
<Thanks! If you can, I sure would appreciate it. I really need to see
the overall shape of the top of the carapace (looking straight down on
it) and to confirm the number of walking legs on each side (are there 3
or 4?). One thing for sure is that it definitely is an interesting
little thing. There aren’t all that many fully marine crabs (if yours is
indeed a fully marine species) that have claws of such different size
like that. You see it regularly in land and fiddler crabs, but not so
much otherwise.>
I haven't confirmed yet, but I think I may have two or more now... I'm
not sure where he came from, he was in my live rock when I got it. The
live rock I used came into my local fish store when a customer traded it
in for store credit. I'm assuming he had it in an established tank for
some time but it could have also crawled into my LR while it was in the
store.
<Yep, at this point it could have come from just about anywhere. That
sort of thing happens all the time. No worries though, we’ll see what we
can figure out! Take care, -Lynn> |
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Crab ID: Xanthid - 10/3/08
Dear crew (particularly Lynn!) --
<Hi there Jonathan, what can I do for you today?>
Just pulled out yet another hitchhiker crab from my live rock.
<Neat!>
Granted, this is old live rock that I've had for a while, so I'm a bit
angry that there are still crabs coming out of it!
<It happens. Crabs are good at hiding and many are nocturnal so it’s
easy for the small ones to go unnoticed.>
Oh well, it's better than everything being dead.
<Absolutely!>
Found this guy when I saw his arm come swinging out of his hole at a
blue gudgeon goby of mine,
<Uh-oh!>
so I think I caught him at the right time!
<Yepper>
I believe, from the black claws and shape, that he's a Xanthid crab of
some sorts.
<I agree. It does indeed look like a Xanthid of some sort. I took a
close look at the photos you sent and saw little hairs on the crab’s
legs. Unfortunately, that doesn’t narrow the choices down greatly, but
with the hairs and the shape of the claws and carapace, it could be
something in the genus Chlorodiella. Here’s an example:
http://www.flmnh.ufl.edu/reefs/guamimg/crustacea/xanthidae/Pages/Image7.html
>
He's been banished to the refugium along with a gorilla crab I found
not that long ago, so they can be cuddle buddies.
<Sounds good.>
Attatched are a few photos.
<Thanks!>
Thanks,
Jonathan
<You’re very welcome. Take care, -Lynn>
Re: Crab ID: Xanthid - 10/4/08
<Hi there, Jon!>
That, to me, is 100% the crab, Lynn.
<Yay! I’m not 100% sure, but it’s at least fairly close. The problem with these
guys is that the differences can be very slight between one genus/species and
another. It can be anything from the number of spines on the side of the
carapace to subtle differences in the claws, etc. You really need to have the
specimen right in front of you to see all the pertinent little details. From
what I could see in the photos, Chlorodiella looked the closest overall. The
species in this genus have the same rather flattened “face” area, wide-spaced
eyes, as well as the same general (blunt-ish) claws and carapace shape (with
spines). What I haven’t seen in this genus is a species with spines on its claw
arms like I see in yours. Unfortunately, there aren’t available photos for every
species of crab, and new species are always coming up, so I just can’t be sure.>
I believe you hit the nail right on the head. The pictures are a bit dark mainly
since I didn't bother to color correct for a snapshot of a crab, but the
markings and everything on that crab in your example seems to be "it"!
<Yep, it’s close, anyway! Bottom line is that it’s definitely a Xanthid of some
sort.>
Are Chlorodiella crabs usually pretty destructive in reef tanks (I would guess
they are by the site of how big my boy was!)?
<That I don’t know. I’ve looked around, but can’t find any information regarding
their diet. Since most crabs are omnivorous though and Xanthids tend to be
carnivorous, you can bet that the larger these crabs get, the more threat they
pose to fish, etc – not to mention the possibility of one rearranging your
rockwork! You did a good thing getting him out of there!>
Thanks again for the ID.
- Jon
<It was my pleasure, Jon. Have a great weekend! –Lynn>
Re: Crab ID: Xanthid –
10/5/08
One further question, Lynn...
<Fire away, Jon :)>
Who are you taking in a fight: Gorilla crab VS Chlorodiella crab?
<Heheeee! Discounting the obvious home tank advantage for the Gorilla, I
think it’s going to come down to weight class. I have a feeling that the
newcomer (the Chlorodiella in the striped trunks) is probably a bit
smaller/lighter than the resident Gorilla crab, so the advantage goes to
the larger/heavier opponent. If, however, they’re both in the same
weight class, the odds change. Both Xanthids would have similar reaches,
reflex speeds, and fancy footwork potential, so as long as both are
healthy and not in the middle of a molt, the odds would be fairly even.
The good news is that if one looses an appendage in the “Rumble in the
Refugium”, it’ll grow back within a couple of molts!>
I think I need to videotape this and put it on Pay-Per-View. Could
generate more ratings than Kimbo Slice!
<Ahhh, if only!>
- Jon
<Enjoy! –Lynn>
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