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FAQs about Marine Crab Identification 9
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
7, SW Crab ID 8, &
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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Mystery crab 08/08/2008
good day from Oregon
<<Good day from sunny England. Andrew here today>>
I am new to reefs (saltwater for the truth) and have found out that you
inherit what is in the live rock . I have found around 5 brittle star
type fish 3 or 4 other types of star fish , red feather dusters along
with other brilliant thing AND one not so good guy . on the picture
attached ,the best one I could get of him , he is in the center of the
photo in the hole . has pinkish white hairy legs dark black main body .
Good guy bad guy? anyways I found the mention of traps, I am going to
try to capture it tonight . if you could ID it . Where I got the live
rocks, they says it a hairy crab (little vague if you ask me).
<<A little too hard to say / make out from the picture you supplied.
Please do look have a look here,
http://www.wetwebmedia.com/marine/inverts/arthropoda/crabs/swcrabs.htm
and related FAQ's and articles. Maybe trap the crab, put in a plastic
tub and photograph / re-submit and we shall try again.>>
James
<<Thanks for the question. A Nixon>>
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Hitchhiker crab 07/28/2008
Hi
<<Good evening, Andrew today>>
Caught this crab this morning. I knew he was in some Live Rock last
October. Amazing markings. Do you have any idea what species he may be?
<<My educated guess would be that its a Anomuran crab, from the family
Porcellanidae family. One I would consider reef safe>>
Cheers, Michael
<<Thanks for the question, A Nixon>>
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Hitchhiker Crab – 7/28/08
Hi, guys!
<Hi there!>
I will keep it short. I found this dude in my live rock and flushed him
out by removing the rock and running fresh water through my star polyps
where he was living. <Yikes!> Do you know what species he is?
<I wish. Unfortunately, I can’t see enough detail to even narrow it to
family/genus level. Suffice it to say though, that crabs are
predominantly opportunistic omnivores, so the potential is there for it
to pose a threat to other livestock. This is particularly true as the
crab grows in size. If the crab is fairly small right now, you could
either leave it in place, monitor and trap if/when necessary, or simply
find it another home elsewhere. It’s up to you.>
I searched your site and the internet and found many nice crab photos
but none like him. Thanks.
<You’re very welcome!>
http://www.fishpondinfo.com/photos/crustaceans/crabs/scary1.jpg
http://www.fishpondinfo.com/photos/crustaceans/crabs/scary2.jpg
http://www.fishpondinfo.com/photos/crustaceans/crabs/scary3.jpg
http://www.fishpondinfo.com/photos/crustaceans/crabs/scary4.jpg
It's ok if you don't know.
<Thanks, it always frustrates me to not be able to get an ID for
someone, but crabs are notoriously difficult in that regard. There are
just so many thousands of possibilities that it boggles the mind. Our
best chance at identifying these neat little creatures begins with
detailed/high resolution photos from above and below (including all
legs), as well as views from the front, showing the claws, eyes/eye
placement, etc, along with information such as size and where it came
from. Even then, it can be frustratingly difficult due to the lack of
readily available photos of every crab on the planet. With that being
said however, we can usually narrow things down to family level which is
at least a good start! Again, I apologize for not being able to supply
this for you. Good luck with your little crab. :-) Take care, -Lynn> |
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Re: Hitchhiker Crab, Plus Possible
Poriferan – 7/28/08
<Hello again!>
Thanks so much Lynn even though you didn't know what he was!
<You’re very welcome!>
I thought I was the only person on the internet who still answers all
questions and promptly! It's hard work!
<Well, we do our best, and yes, it can indeed be hard work – but it’s
well worth it!>
I run a huge web site myself mostly on freshwater aquariums and ponds.
<Excellent, so you can definitely relate, huh!>
People don't realize how much time it eats up to respond to so many
questions. I thought my photos were pretty good, in fact better than
looking at him in person since he's so tiny!
<I’m sorry, they were indeed good photos, especially for a small crab!
It’s just that when it comes to identifying these critters, and
especially crabs, it’s all in the details. These include
shape/texture/color of the overall carapace, whether it’s smooth or
“hairy”, the number of spines/shape of the carapace edge, eye
placement/color, length of eye-stalks, how many legs, the
shape/length/color of legs and claws and whether there are any “teeth”,
spines, bumps, etc, on them, the shape of the tips of the claws (are
they pointed, blunt, or spatulate), the depth of the body, etc, etc, and
that’s just the basics. LOL The list of criteria goes on and on! The
best way to ID these guys is to have it directly in front of you so that
you can pick out all the details.>
The little crab is in a 3 gallon exile tank
<Good>
with the Emerald Mithrax crab the store guy told me would be great
(great at picking at my star polyps as it turned out).
<Yep, that’s annoying for sure!>
The crabs seem fine but haven't run in to each other yet.
<Very good. I’m so glad to hear that he’s got a good home. Many of these
neat little creatures end up being disposed of and that’s a real shame.>
Now, that I know someone may be able to help in my new foray in to
saltwater, I have a few other unidentified thingamabobs in my tank. One
has appeared out of nowhere and grown really fast in under a week. In
fact, I didn't even notice it until about three days ago, and it's
doubled in size.
<Yowza!>
It's attached to the live rock under my favorite hitchhiked feather
duster. The base is a little fuzzy. The stalk is pastel yellow, almost
like a crayon. It has no real mouth, arms, or legs or anything but it is
growing. I will have to get a photo.
<Please do, I’d love to see it.>
It looks like it's calcareous. Today, the tip changed in appearance to
have a rectangular-shaped protrusion. It kind of curves up at the end.
I'm guessing it's either a strange yellow algae or perhaps a fungus (are
there freshwater funguses?).
<Sure, there are marine versions as well. Fungi are everywhere. I’m
thinking that what you have though could be a Poriferan/sponge of some
sort (would need to see a photo). The neat thing about these guys is the
diversity of shape and color that they come in. It’s truly amazing. For
more information/photos, please see Bob’s pages regarding sponges,
starting here (3 pages): http://www.wetwebmedia.com/sponges.htm . Be
sure to check out the associated links at the top of the link as well!>
The little feather duster really doesn't like it since it's in its
space! I'm wondering if I should bust it off.
<Hmmm, well it depends. If it is indeed threatening something you like,
you could attempt to remove the offender (although if it’s a sponge,
many times they simply grow back). If you do (and in case it’s a
sponge), I’d remove the rock from the tank first. I’d take it out,
scrape away as much of the offender as possible, then scrub the area
with a toothbrush, and rinse *well* with tank water (into a bucket or
similar). Also, you might want to check your nutrient levels/nitrates.
The organism’s rapid growth could be an indicator of such. In the
meantime, if you can get us a photo, we’ll see if we can’t narrow
down/confirm what you’ve got there!>
Thanks again.
<You bet. Take care, -Lynn>
Update Re: Hitchhiker Crab, Plus
Possible Poriferan, Macroalgae – 7/30/08
<Well hello again!>
Ok, I threw up some photos quickly since I'm low on time.
<Appreciate it!>
Photo of the entire 12 gallon nano cube showing where the "thing" is:
http://www.fishpondinfo.com/photos/other/other/temp1.jpg
<Nice looking system.>
Photo of the thing a few days ago when it grew fast and was yellow. My
favorite little feather duster is open to the right of it.:
http://www.fishpondinfo.com/photos/other/other/temp2.jpg
<Neat>
Photo from today of it with the feather duster, zooanthids, xenia,
macroalgae, etc. When I came home, the thing had turned green!:
http://www.fishpondinfo.com/photos/other/other/temp3.jpg
<Ah yes, that helps. It looks like some sort of macroalgae, possibly in
the genus Halimeda (a calcareous algae). We should be able to tell when
it gets a bit farther along (if it’s that or something else). Here are
some links re:
http://www.wetwebmedia.com/greenalg.htm
http://www.reefkeeping.com/issues/2004-04/nftt/index.php
Good photos here: http://www.reefcorner.com/SpecimenSheets/halimeda.htm
It definitely likes the light. <Yep> There were no sponge matches on the
site you gave me but fan sponges seem to come the closest. Is that what
it is?
<Don’t think so.>
The feather duster has bent itself off to the right to avoid bumping in
to this thing that I swear wasn't there at all a week ago!
<Funny how things spring up like that isn’t it! It’s a matter of
conditions becoming favorable for the organism’s growth/survival.>
I put in about 15 mL of RowaPhos weekly in a little mesh bag to keep the
phosphate low. I use RO water. It takes over two hours to make 3 gallons
once a week.
<Yikes. That sounds like an awful long time to make just 3 gal’s of RO
water (is it RO only or actually RO/DI?). Here are some contributing
factors to low production: a connection/plumbing problem, small unit,
clogged/exhausted membranes, very cold water, or low water pressure.
Just for comparison, I have a Typhoon III (75 GPD) RO/DI unit from
AirWaterIce that takes about 45 min’s to make 3 gallons. That’s with the
(tap)water pressure at about 68-70gph. In the winter when the water is
in the fifties(F) it takes about an hour instead. I’d go through the
above list and see if anything pops.>
I don't know how those with large tanks do it; they must run the RO all
the time which I'd be afraid to do (leaks, wasting huge amounts of
water; we're on a well).
<Ah, I see. Have you checked the TDS (total dissolved solids) level of
the well water? If it’s really high, you may be exhausting/clogging the
membranes pretty quickly. That would definitely slow things down.>
Here are two other photos if you can confirm what I think they are:
Pineapple sponge?
http://www.fishpondinfo.com/photos/other/other/squirt.jpg
<Ding, ding, ding! You are correct. It’s a harmless/beneficial little
Syconoid sponge, aka a Pineapple or Q-tip sponge.>
Sponge of some sort (the yellow thing at the top of the rock)?
http://www.fishpondinfo.com/photos/other/other/sponge.jpg
<I can’t quite tell, but yes, it could be that or one of several other
harmless organisms, like a Bryozoan.>
Thanks again!
<You’re very welcome! Take care, -Lynn>
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Re: Crab ID
-07/18/08
<Am sending this mystery to our fave
ID'er... Lynn... stay tuned... BobF>
WooHoo - fave ID'er! Thanks Bob! I
actually saw this query last night but didn't grab it because I knew I
wasn't going to be able to send a reply until later on this afternoon or
tomorrow. I've had a couple of things come up that I need to tend to,
but I'll dig in as soon as I can :-)
Take care and have a great weekend!
-Lynn
<Thank you Lynn... not just being lazy... am away from ref. works!
Cheers, BobF>
<<LOL Lazy is a term that I would never associate with you! I can't
imagine having your schedule - or workload! I left that query in case
someone else had the answer(s), but I'd already planned to nab it this
morning if it was still unanswered. You know I'm always happy to take
the critters! :-)
Hope you have some fun plans lined up for this weekend. We're having
some friends over tomorrow night for dinner and mucho Tequila. Wish you
were in the neighborhood!
Take care,
-Lynn
<Ahh, tah kill yah! Very good ones (triple distilled) are faves of many
folks in the livestock whlse. trade for some reason... The smell always
seems to remind me to roll up my sleeve... Cheers! Kanpai! Twenty three
skiddoo, and pass me the aspirin. BobF>
Crab ID: Likely Xanthid – 7/18/08
Dear WWM Crew,
<Hi Kevin>
We bought a very small piece of live rock...and now have two very large
pain in the glass hitchhiker crabs. They are not large...just large
pains.
<They certainly can be!>
I think one of them ate the arm off my starfish...hmmm.
<Oh, not nice at all.>
I have included a photo here as it seems you have had someone ask about
this crab before, but their photo was very blurry and I cannot tell.
Questions are: What type of crab is it?
<Looks like a Xanthid (Family Xanthidae) of some sort. I’m sorry I can’t
be more specific.>
What should we do with it?
<I would find it another home.>
The second crab...is also hairy like this one but more "spiny." However,
I cannot catch him...seems like some late nights are ahead.
<Been there, done that! If/when you do get him out of there, please do
send along a photo and we’ll take a look at it. Also, if you know where
the rock came from, that would be great.>
Thanks,
Kevin
<You’re very welcome. Take care, -Lynn> |
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Strange Crustacean: Need More
Information - 7/11/08
Hi. My name's Brian,
<Hi Brian, Lynn here this afternoon.>
..and I recently went to South Padre for the second time,
<What a great place that is!>
..and once again I caught this strange crustacean. I caught one on my
first trip to SP and spent days trying to identify it on the internet
but never found anything, and the same thing this time...I Googled "sand
flea", "sea lice", South Padre crustaceans", but could never find what I
was looking for.
<Yep, that’s frustrating.>
It surely can't be a new species because I saw several of them and I
can't be the only one who's come across one. But anyways, the crustacean
looked somewhat similar to a horseshoe crab. It was about 1 inch long
with a thin tail that was a couple of inches long. It was a pale white
color, had several overlapping segments to its carapace, and I couldn't
find any eyes on it. On the bottom it had, I believe six legs, and each
leg was like a small crab pincher. Please help me identify this
creature...I really really REALLY wanna know what it is!
<Me too! In all the years I’ve been going to the Texas coast, I’ve never
seen anything quite like what you’ve described. I looked around, did
some research and finally asked a nice fellow from the Natural History
Museum in Los Angeles for some help. Unfortunately, he needed more
information. He said that what you saw could be anything from a dead
Mole crab with its thin abdomen extended out behind it, to a large
isopod of some sort. Here’s a link that shows a bit more regarding Mole
crabs (Emerita spp.):
http://www.diatribune.com/marine-life-series-mole-crabs . The creature
also sounds a bit like a Cumacean, but I’ve never heard of one that
large and besides, they have more than 6 legs. Here’s a link with more
information regarding Cumaceans: http://en.wikipedia.org/wiki/Cumacea.
Unfortunately, at this point, I’d really need a good close-up photo in
order to have any chance at getting an ID for you.>
I wasn't able to get a very decent picture, the one we got is blurry,
and my step-dad isn't letting me have it for some reason.
<Well Brian, the next time you go back to Padre Island be sure to look
around for more of the little critters. You might want to see if your
camera has a “Macro” mode/setting, usually indicated by a small flower
or daisy-like icon. In macro mode, you should be able to get some good
shots. At that time, please do send them along. I’d love to solve this
little mystery! Take care, -Lynn>
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Re: Strange
Crustacean: Likely Mole Crab - 7/11/08
Hello again.
<Hi Brian!>
So this time I've included a picture, it's still blurry but it was the
best one out of five, and in conjunction with my description you can see
a little better what I was talking about.
<Yep, thanks for sending that along. It makes all the difference.>
I looked up more pictures of both of your suggestions, and I think the
creature I caught was likely some kind of mole crab
<I agree. It definitely looks like a Mole or Sand crab of some sort –
something in the Superfamily Hippoidea, possibly in the Family
Albuneidae.>
..(although it wasn't dead, because it was crawling around in my hand),
the only difference was that most of the pictures I found of mole crabs
didn't have the long thin tail I described (which you can make out in my
photo).
<Interestingly enough, I’ve seen Mole crabs that look very similar. The
only difference is that what looks like a tail is actually a pair of
antennae on the head. Take a look at this photo:
http://www.dnr.sc.gov/marine/sertc/images/photo%20gallery/Albunea.jpg .
At first glance, it looks like the narrower end on the right *should* be
the head, but it’s not. It fools the eye a bit. Here’s another link with
more information on Mole crabs in this Family:
http://www.crustacea.net/crustace/anomura/www/albunei.htm.
They’re neat looking little critters, aren’t they!>
But for now, I'm gonna assume that I caught a mole crab....but let me
know if you have any other opinions.
<I think we’ve got it!>
Thanks for the help.
<You’re very welcome and thanks again for sending in the photo! Take
care, -Lynn> |
Re: Another questions :) ATTN
Mitch... crab ID, WWM Crewmember gender/name mis-ID
6/10/08
Hi Mitch,
<Hi Patrick,>
While I was pursuing the aiptasia tonight (got a good start)
<Congrats.>
I noticed a little green crab in my turtle grass, then I noticed there
are 2...
<perhaps a breeding pair.>
I don't know how I missed these guys.
<Easily done.>
They aren't emeralds,
<No they are not.>
Looked all over WWM can't find any that look like these, although I did
see a post about a crab a guy found in his turtle grass and you guys
weren't sure what it was...
<Sorry, I'm not too much help here. It is a very distinctive crab, and I
thought I might be able to find more information for you. From the
images it does appear to be a very pretty shade of green, which I
thought would be most helpful in the identification. I also thought the
turtle grass might be a clue as well but I didn't have any luck
searching along that route either. I'm at a loss. Your crabs appear a
little more refined and sort of remind me of some commensal crabs found
in association with some corals, but most crabs are opportunistic
omnivores and are not to be trusted. You might want to isolate these
guys in a sump so they don't cause trouble. More info here:
http://www.wetwebmedia.com/marine/inverts/arthropoda/crabs/swcrabs.htm
and related links in blue and here:
http://www.chucksaddiction.com/hitchcrabs.html
Cheers,
Michelle> |
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Re: Another questions :) ATTN
Mitch... crab ID 6/23/08
Thanks Michelle,
<Welcome Patrick, sorry for the long delay. I was hoping to come up with
an ID for you, but didn't make much progress, sorry.>
I was leaning towards some sort of porcelain crab but after watching
them for a while last night I was able to see that they have 4 legs on
each side in addition to their claws so they are true crabs. Also I
noticed that the very tips of the claw has white on them. If you guys
don't know what they are they must be very uncommon.
<No, not necessarily, but not something I am familiar with.>
Not sure what to do with them, they never seem to leave their turtle
grass home and as I was watching them last night, they seem to be filter
feeding,
<It is possible.>
they climb up the grass, push it apart and you can see their mouth parts
going a mile a minute.
<I would likely allow them to stay in place.>
I had one of the turtle grasses in the sump for a while, it didn't like
it there, probably because of the crappy light 4700K compact fluor bulb
I have down there... It turned yellow,
<Mmm, sounds like it wasn't getting enough nutrients, may have been more
a sandbed issue than a lighting issue, Thalassia prefers a deep,
enriched, substrate, 3-4 inches minimum, for optimum growth and
development, thought the grass would prefer closer to daylight lighting,
ie 10,000K.>
I moved it to the main tank and it started growing like crazy!
<Better conditions for it. Good luck with these little guys. I would
just keep an eye on them.
Cheers,
Mich>
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Please could you ID this crab: Likely Xanthid
- 6/7/08
Hi,
<Hi Ranjith, Lynn here today.>
I found this fellow in my 5 month old tank.
<Okay>
Couple of observations in the tank (might be or not because of him).
1. Found empty shells of similar but small crab (maybe this one moulted?)
<Either that, or there are multiple crabs present.>
I observed this over last 2-3 months. From the last 2 weeks he is active and is
seen around the tank.
2. Found a piece of my moon coral torn off.
<Ouch!>
I saw him trying to burrow under the moon coral once a week or so ago but he
left the place in some time. He does not go there as far as I have observed but
maybe when it’s dark??
Yesterday night I found a small 2cm piece of the moon coral not far from the
coral itself.
<Mmmm, not good.>
Other inhabitants are:
1. Flame angel
2. Bicolor blenny
3. Skunk clowns
Tank is 120 gal bowfront
Would you need more info to ID this crab?
<Unfortunately, there are so many possibilities that without having the crab
directly in front of me and knowing where it’s from, the best I can do is ID it
to one of two families. The first is Cancridae. These are also called “Rock
crabs” and often have fluted, toothed, or scalloped carapace edges. I can’t
quite tell in the photograph if your crab has this feature or not. It actually
looks rather smooth to me, so if that’s the case then it’s more than likely
something in the family Xanthidae. Xanthids, (“Mud” crabs) are common
hitchhikers and are unfortunately some of the more notorious crabs as far as
their potential for being destructive. Some are coral commensals, and relatively
innocuous, but all are omnivorous with the potential to cause problems. That
goes for crabs in the family Cancridae as well. I would recommend either
trapping and relocating this crab, or keeping it well fed in hopes of
discouraging it from sampling your desirable livestock. If it were me, I’d
relocate it. For more information, please see the following links:
http://www.wetwebmedia.com/marine/inverts/arthropoda/crabs/swcrabs.htm
http://www.chucksaddiction.com/hitchcrabs.html
http://en.wikipedia.org/wiki/Cancridae
Cheers and Thanks Again
Ranjith
<You’re very welcome! Take care, -Lynn>
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Small crab in brain coral 5/13/08
First off, let me say this is the greatest site I've ever stumbled upon
and you've answered many of my questions about my reef tank. Now, here's
my situation: I bought a colored brain coral this weekend. The coral has
been inflating and deflating throughout the day, and it has eaten but
today I noticed a spot that I thought was tissue recession. After
observing it all day, I saw that it is a tiny (I mean really tiny) crab
living inside it. It has eaten a tunnel out of the coral.
<It is a coral-gall crab or gall crab... very interesting creatures.>
I tried to remove it with tweezers and I thought I killed it, but it
just backs up into the coral and I can't get it. I don't want to lose
this coral, but I really don't want the crab to migrate to my pride and
joy bubble coral, or any of my other LPS. Do you think this crab will
eat the coral its in?
<No worries, they are harmless and don't appear to reproduce in
captivity (or, if they do, not enough that anyone has ever reported a
problem with them). I myself have had both a male and a female in my
tank. The female even had eggs at one point. But I never noticed any
babies (nor any new crabs).>
Is there any way I can flush it out? I really want it gone.
<Aww, please consider letting the little guy live. They're not harmful
and are actually quite interesting little creatures. Some people say
they never leave their holes, but I have this picture I think "proves"
otherwise. Please pay no mind to the state of the coral they're on...
that was not at all their fault, I had accidently dropped the coral in a
bucket of vinegar (actually, come to think of it maybe that's why the
crab came out of the hole). lol That's NOT a suggestion!! ...certainly
did more harm the coral than to the crab! ::sigh::
Best,
Sara M.>
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Black Crab ID: Start With WWM Sources -
4/21/08
<Hello>
Need help ID'ing a stowaway on a Tonga live rock. I haven't gotten a clear shot
of it, he's pretty shy. It's a dime sized crab, all black, with a pattern of
white lines on its back. It has not left the rock it lives in, and when I do see
him, he quickly hides.
<Typical>
I'll send a pic as soon as I catch him.
<Sounds good. Best case scenario would include detailed photos from above,
beneath, and face-on. Even then, identifying crabs to the species level can be
very difficult indeed. However, with enough information we should be able to
narrow it to a basic group. In the meantime, please read through the information
and compare the photos at WWM regarding crabs. Start at this link, and be sure
to go through the associated links at the top as well:
http://www.wetwebmedia.com/marine/inverts/arthropoda/crabs/swcrabs.htm
Take care, -Lynn>
Tiny White Crab on Montipora
capricornis: Gall crab - 4/8/08
Hey all.
<Hi Andy>
I have a Montipora capricornis on which I found a tiny white crab (I
think). When I noticed it this morning, I thought it was simply a piece
of debris hanging off the coral, but tonight with the lights out and a
focused flashlight I was able to see that it was in fact some type of
animal. I was able to suck it off with a turkey baster. It is very tiny,
so without a magnifying glass I can't make out its features very well,
but it does have at least 4 legs on each side.
<Thanks, that’s an important bit to know when identifying crabs!>
The best way I can describe it is to tell you it looks like a white deer
tick.
<Oh man, do I ever despise ticks! They’re creepy little bloodsuckers!>
I have attached pictures--I hope you can make it out.
<Unfortunately, I can’t see enough to differentiate between the two crab
families I have in mind. However, I’m hoping that the photo links I’ll
list below will help you determine which one it really is.>
I searched around on WWM to see if anything popped up on this subject
that might give me an ID, but I came up empty handed. I note that the
flesh of the coral at which this crab was attached all day is totally
undamaged, so I'm thinking (and hoping) that it is not
a threat
<Not likely, no. Most are small commensals.>
(although I disposed of the crab anyway). However, there is a tiny,
round hole in the structure of the coral that is under the place this
crab was attached and that looks like it has been there a while (see
pic--maybe the crab was living in this hole?).
<Very likely, yes.>
Any thoughts on what this crab might be?
<It looks like something either in the family Cryptochiridae (coral
pit/gall crabs – many genera) or the family Xanthidae (genus Cymo - gall
crabs). I’ve never heard of these crabs inhabiting Montipora corals
before, but considering how little I really know and how much I still
need to learn about them, that doesn't mean a whole lot! One thing
that’s going to help that I can’t see in the photos relates to the
claws. If those on your crab were easily seen and fairly robust,
possibly dark tipped, then it’s likely a Cymo sp (xanthid). If, however,
your crab had barely noticeable, slender claws, then it’s likely a
Cryptochirid. The crabs in this last family look more like ticks to me,
but take a look and see what you think (the first two are
Cryptochirids):
Hapalocarcinus: http://cookislands.bishopmuseum.org/species.asp?id=7372
Cryptochirus: http://cookislands.bishopmuseum.org/species.asp?id=7200
Cymo: http://decapoda.free.fr/illustration.php?n=3&sp=212 >
As always, thanks for your help/time.
Andy
<You’re most welcome. Take care, -Lynn>
Re: Tiny White Crab on Montipora
capricornis: Gall crab - 4/8/08
Lynn,
<Hi Andy>
Thank you for the response.
<You're most welcome.>
Hmmm, hard to tell. The claws definitely were NOT noticeable. In fact, I
couldn't see them at all--the only things I could see were the 4 legs on
each side. It resembles the Cryptochirid, but doesn't look like an exact
match.
<It may be something else within the Cryptochiridae family.
Unfortunately, those were the only two online examples I could find of
the different genera within that family. Depending on where you look,
there are anywhere between 6 to 20 different genera and beyond that, a
whole slew of species so there are lots of possibilities.>
I'm just glad it likely was not harmful to the coral.
<Me too!>
The marine world is a strange and fascinating one.
<It is indeed! Take care, -Lynn> |
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Sea Apple Hitchhiker:
Pea Crab - 3/21/08
Hi,
<Hi there Joe>
I am researching this for someone and I haven't been able to get an
answer as of yet, I was hoping someone here could help me.
<Hope so!>
This particular issue is with a Sea Apple <Uh-oh> it showed signs of not
doing so well for a few days. There was a white portion of it looking
like it was deteriorating and
expelling its insides.
<Not good>
Since then and further observation the owner noticed that there was
something inside the sea apple, it was a small crab or what looks like a
crab.
<Yep>
Do you know or have heard of this happening,
<Not specifically with Sea Apples/Pseudocolochirus spp., but I’ve heard
of it in relation to other Cukes/Holothuroids. Sea cucumbers can be
hosts to many different organisms, including Pearlfishes/Carapidae,
Polynoid Polychaete worms, Periclimenes shrimps, as well as crabs
(Pinnotherids, Portunids/Lissocarcinus orbicularis,
Eumedonids/Hapalonotus reticulatus, etc.).>
and what type of crab this is.
<Looks to be a Pea Crab, family Pinnotheridae. These are small crabs
that live in Cukes, tunicates, bivalves, etc., with varying degrees of
commensalism to downright parasitism. While some live and do only low
key, if any damage to its host, others can cause more threatening
damage, such as atrophy of the respiratory organs/“trees”. Here are some
examples of this family of crabs:
http://www.unige.ch/sciences/biologie/biani/msg/teaching/photos%20liste/Pinnotheres%20pisum.JPG
http://outdoors.webshots.com/photo/2762668420086890761xKfyFR >
I attached a pic for reference,
<Thanks, good photo!>
up until the white deterioration of the portion of the apple it was
healthy and doing well. Tank is a 150gal, 0 nitrates, salinity 1.024 and
pH 8.4.
<I'm guessing that the crab has been removed permanently from the Sea
Apple. If not, I would do so. I would also recommend keeping a close eye
on the Sea Apple for further decline. They can do significant damage to
a system when they die! Please see this link for more information re:
http://www.wetwebmedia.com/seacukes.htm >
Joe Brillon
<Take care, -Lynn>
Re: Sea Apple
Hitchhiker: Pea Crab – Now, Sea Apple in Trouble - 3/24/08
<Hi Joe>
Thank you very much for your response as I have passed the info on.
<You're very welcome.>
It appears now that the area of concern has worsened.
<I’m so sorry.>
And the cause is unknown...any idea's what could of caused deterioration
in the body of this animal?
<No, I’m sorry to say that I don’t. There are many possible causes
including predation/picking/rough handling at some point. It could have
gotten too close to a heater, pump intake etc, or it could be starving
and deteriorating. These are notoriously difficult animals to keep. They
need pristine/stable water conditions, a good supply of food, and lack
of predation to survive - and in this case, to have a shot at recovery.
Also, unless the Sea Apple is in a species tank/kept alone, I would move
it to a quarantine tank to avoid the possibility of its poisoning the
other tank’s inhabitants. At the very least, I’d run carbon/PolyFilter,
and have a large amount of prepared water on hand for a major water
change should the cuke decline further/die. Signs of decline would
include deflation, expelling of insides, and losing color. Either way,
I’d have a QT set up for either the cuke to go into immediately, or the
fish/shrimps, etc, to be moved into should the worst happen. Please see
this link for more information regarding Sea Apples/tank poisonings.
http://www.wetwebmedia.com/cukeselfaqs.htm >
Joe Brillon
<Sure hope everything works out for your friend and the Sea Apple. Take
care, -Lynn> |
|
Crab soup du jour? |
LR
Hitchhiking Crab ID Please: Xanthid and Possible Lissocarcinus sp. –
3/20/08
Hi Crew,
<Hi there Tracy!>
I'm hoping you can help me id these two little guys that have been
living in my Fiji live rock. They're crabs, but definitely not the ones
I bought! Both very shy but have made a few appearances. They've doubled
in size since we noticed them in our setup (now almost an inch across).
They don't seem to bother any of our hermits or snails, however, 3
hermit crabs have gone missing, one of our newest has lost an arm, and
our Skunk Cleaner Shrimp has just finished growing one of his arms back
(we initially thought due to one very territorial yellowtail blue
damsel).
<Feisty little fellas!>
Could these guys be the culprits instead?
<If the two crabs are about an inch across the carapace (not including
the legs), then yep, it’s entirely possible. It could instead, though,
be another larger hermit, crab, or even another shrimp depending on what
species. There are lots of possibilities.>
I've managed to narrow the first one down:
<Good for you, I’m truly impressed! I know how time consuming and
challenging this process can be!>
..it wouldn't be Hoplophrys oatesii b/c they're too spiny; it wouldn't
be Mithrax cinctimanus b/c they're too fuzzy looking; could it be a
variant of Lissocarcinus laevis or Lissocarcinus orbicularis??? The last
seems most likely to me.
<Yep, it could be that or something else in the same genus. Check the
last/rear pair of walking legs for paddle-like structures on the tips.
Lissocarcinus is in a family of swimming crabs, Portunidae, so the
presence/absence of these should help confirm/exclude.>
The second photo shows only the exoskeleton of the white-armed crab (his
eyes are missing). I haven't been able to figure him out at all.
<Looks like one of many possible Xanthid species (sorry I can’t be more
specific). Some are commensals, others just hang out in the
rockwork/substrate. All are opportunistic scavengers (same goes for
Lissocarcinus). As neat looking as both of these crabs are, they
unfortunately have the potential to become destructive, particularly as
they grow larger. You could try to deter predation by keeping them well
fed, or instead place them in a sump or the like where they can’t get
into any trouble!>
Thanks for your time and the great work you all do!
Tracy
<On behalf of Bob, the crew, and myself you’re very welcome! Take care,
-Lynn> |
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Crab ID:
Family Menippidae - Predator! 3/18/08
Hi,
<Hi there!>
I was wondering if you could identify this hitchhiker for me.
<I'll sure try!>
At the moment he is about 1cm so very small.
<Good>
He only appears to come out when I feed the tank and is quite happy
waiting for a piece of flake to drift into his home (I cannot of course
be sure what he is doing overnight - probably terrorizing the tank!)
<Yep, these guys are nocturnal predators. During the day, they seem to
be mild mannered, snatching tidbits here and there, but at night it’s
another story! The shape and red eyes are very characteristic of crabs
in the family Menippidae, Superfamily Xanthoidea, otherwise known as
“Reef” or “Stone” crabs. I’ve seen similar (if not the same) crabs
tentatively identified as belonging to the highly toxic if ingested(!)
genus Eriphia (within the family Menippidae), but I can’t confirm it.
Although these claims could well be correct, a slight
unseen/unrecognized physical characteristic could easily place the
crab’s classification elsewhere. Aside from taxonomic issues, these
fairly common hitchhikers can unfortunately be very aggressive towards
other crabs/invertebrates, as well as small fishes. At this size, it’s
not likely to do too much damage, but unless you’ve got a large fish, FO
system, I’d think about moving it to a sump/elsewhere. Please see this
link for an example of several crabs in the family Menippidae:
http://www.geocities.com/ericdemuylder/menippid.htm. You can also see
several photos of very similar crabs at WWM. Use the Google search
engine with the terms “Eriphia” and/or “crab + red eyes”:
http://www.wetwebmedia.com/WWMAdminSubWebIndex/question_page.htm.>
Many thanks in advance
<You're very welcome! Take care, -Lynn> |
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Crab identity... no use of
WWM, rudeness 03/15/2008
Help! I bought a small crab with light blue color on the top of the shell
from my LFS. The store did not have another name for it and did not have any
culture information. I am also wondering what I should feed the crab? Thanks Art
<... Uhh... a terrestrial hermit? Saltwater, fresh? Try using the indices,
search tool on WWM. B>
Re: Worm ID
Please, Now Crab ID - 3/3/08
Hi!
<Hi Cath, this is Lynn filling in for Bob this evening!>
Thanks for the answer.
<On his behalf, you’re very welcome!>
I've got now another ID for you. That was a little hairy crab who host a
Monti colony of another reefer of my area.
<Okay>
Look at the joined pieces please and tell me if it is reef safe or not
and if you can ID this crab.
<Hmm, it’s hard to figure out what’s what in the photo, but it’s likely
a little (coral) commensal xanthid crab. As far as whether it’s reef
safe - likely so, as long as it stays small and doesn’t irritate the
coral too much. That is, if it’s still alive. Judging from the use of
past tense and referral to "pieces", I'm not so sure! If it is indeed
still alive, I’d keep an eye on things, offer it small meaty bits (of
marine origin) to deter predation and remove if necessary.>
Thank you! Regards.
Cath
<You’re very welcome! Take care, -Lynn>
Follow-up: RE: Worm ID Please, Now
Crab ID - 3/3/08
<Hi Cath!>
Thanks for the answer Lynn!
<You’re very welcome!>
Sorry for my bad English,
<Your English is just fine, so much so that I didn’t realize it wasn’t
your first language!>
I usually speak French and I have little difficulties with verb
tenses!;-)
<Well, I can sympathize as I have the same problems now and then myself
and it *is* my first language!>
Have a nice day!;-)
Cath
<Merci bien et vous aussi! -Lynn> |
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Two Crabs and a White
Nudibranch? 2/24/08
Hello crew!
<Hi there!>
I've attached a few pics of life (and former life) that I cannot
identify. Whilst my intent was not malicious, the two crabs did not
survive the extraction.
<Unfortunate, but understandable - can be difficult to remove!>
As you can see, one is missing several appendages. <Yep> I would've left
them alone if my scarlet hermits were not being ripped to pieces at
night <Yikes!> and if I hadn't read Calfo's opinion that crabs should be
removed.
<They can indeed be very destructive.>
So, right or wrong, they are out and no longer alive. For the sake of
learning and not repeating a mistake if they were harmless, can these be
identified from the pictures I've provided?
<They appear to be in the superfamily Xanthoidea. The hairy crab looks
like it might be in the family Pilumnidae while the other could be in
one of several different families. No matter, this group of crabs can be
very destructive and I would have recommended their removal. Please see
these links (and those within at WWM) for more information and photos
for comparison:
http://www.wetwebmedia.com/marine/inverts/arthropoda/crabs/swcrabs.htm
http://www.nhm.org/guana/bvi-invt/bvi-surv/crab-g06.htm>
Also, there is a small interesting white (Nudibranch?) life form in my
tank. Pictures also attached. Ideas about ID?
<Unfortunately there are just too many possibilities. I can tell you,
however, that due to their specialized diets, these little guys do not
usually survive long term in most systems. Please see the following
links, especially the section at the bottom of the first regarding
issues associated with Nudibranchs:
http://www.wetwebmedia.com/nudispt3.htm
http://www.seaslugforum.net/ >
Thanks so much.
<You're very welcome! Take care, -Lynn> |
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Crab ID
Needed – Acropora Commensal! 1/19/08
Hey, guys and gals -- 3rd letter this week!
<Yay! What can I do for you today?>
I bought my first piece of Acropora coral and I was pretty excited.
<Understandably so, they’re beautiful corals!>
Well, guess what? A little buddy hitchhiked his way on the coral! He's
pretty much all off white with a bit of blue-ish purple on his shell.
<Yep, I’ve seen this little guy’s kin before. They’re neat little
crabs.>
He looks nice and was snuggled in the branches of the Acropora frag but
I have no idea if he's a good guy or bad guy. If he's bad, I would guess
it'll have to be the sump for him until my refugium gets built!
Here are some pictures to help with the ID. Hope they are clear enough!
<They are, thanks! I’m happy to say that this little crab is a keeper.
Ninety-nine percent of the time, when people write in about hitchhiking
crabs, we have to warn them about the potential risk to their livestock.
This, however, is the one percent that makes for an exception. What you
have is a little Acropora (commensal) crab, in the genus Tetralia. They
stay small, and are actually good for the coral. Interestingly enough,
in the wild, this crab protects the coral from the voracious
Crown-of-Thorns sea star (Acanthaster planci). It pinches the tube feet
of the star and "discourages" it from dining on the coral! I have a link
for you to read through for additional information, as well as several
others with photos:
http://www2.hawaii.edu/~delbeek/afmjan97.html
http://home2.pacific.net.ph/~sweetyummy42/hitchcrabs.html
http://home2.pacific.net.ph/~sweetyummy42/coral_crabs-2.html .>
Thanks,
Jon
<You’re very welcome. Enjoy your new additions! –Lynn>
--
Jonathan Philpot |
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Hitchhiker Available
For Food 1/14/08
Hey there.
<Howdy>
Enjoy the pics of this guy I caught over the weekend! With those red
eyes, probably nocturnal, coming out to creep when lights out? I think
it must be over 3 years old, since that's the last time I added any live
rock. He's currently being fed & held in a container in the tank. Hoping
someone local may need some puffer or mantis food or want it for a sump.
CRAB PIC 1
<http://stonyreef.com/blog/wp-content/uploads/2008/01/crab.png>
CRAB PIC 2
<http://stonyreef.com/blog/wp-content/uploads/2008/01/crab2.png>
<Gee thanks for trying to share with us, but a copy/paste of the links
leads me to
error pages. Best to attach photos to the email. James (Salty Dog)
Hitchhiker Available
For Food 1/15/08
Attached :)
<Got them now, thanks for sharing.>
Thanks!
<You're welcome. James (Salty Dog)> |
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Can you help ID this crab?
Mithraculus? 1/13/08
<Hi there>
Found this hitchhiker in a piece of live rock. Took me quite a bit of time to
coax him out with some food. Is this crab reef safe?
<Depends on what you have in your tank, but crabs in general are not a good idea
in a mixed reef tank. They’re mostly opportunistic omnivores, and “pickers”,
that may start out small and cute, but can become a problem later on (nabbing
fish/other inverts, picking on desirables, etc).>
What kind is it?
<Not sure - would need to know where it was from, as well as a shot from above
showing all legs/shape of the carapace, as well as one showing the claws.
Judging by what I can see in the photo though - hairy walking legs and what
appears to be the potential for blunt/clubbed claw tips - it looks somewhat like
a Mithrax/Mithraculus sp. This is the same genus as the commonly offered
“Emerald Crab” (Mithraculus sculptus) that some use for algae control. Most have
more pointed "faces", but some do not. Next time you see him out and about, take
a close look at the tips of his claws. If they’re blunt/spatulate instead of
sharp/pointed, then it likely is a Mithrax. However, it also looks like it could
be a Pilumnus species (Family Xanthidae), although it’s hard to tell in the
photo if the carapace/claws are hairy, and if so, to what degree? Xanthids are,
unfortunately, some of the more destructive candidates for reef tanks. For more
information, please see these links (as well as related links listed above at
the WWM link):
http://www.wetwebmedia.com/marine/inverts/arthropoda/crabs/swcrabs.htm
http://www.reefkeeping.com/issues/2003-12/rs/index.php>
How big will/can it get?
<Can’t be sure without knowing which species we’re dealing with.>
Any input is much appreciated.
<You’re very welcome. Keeping a crab in a reef tank is a risk, but if you decide
you’d like to let him stay, keep an eye out for damage and trap/remove if/when
necessary. Take care. -Lynn>
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Mystery crab
hitch-hiker -12/22/2007
Hello gang.
Thanks for such an incredibly comprehensive site! Thanks to you, I've
given up searching the rest of the web most of the time anymore.
<Haha... thanks.>
On to the question: I'm looking for an ID on this crab, if possible. He
showed up magically in my refugium-to-be a couple days ago. The refugium
was set up about 2 weeks ago in preparation for an order I had coming
from Floridapets.com. Although the tank itself hasn't been up and
running for all that long, nearly all of it's contents came from a 10
gallon and a 5 gallon tank that had been going for about 3 months
previously. It's a 29 gallon with deep sand bed, powerhead, whisper
internal filter (rated for a 10 gallon, but mostly just used for
circulation), and a cheapo style Berlin skimmer (air stone type). My
plan is to let all the recent arrivals be in that tank for a month or
two before I hook it up to my 20 gallon nano reef as a refugium. I'm
monitoring the water quality closely, especially since this tank is so
recent to be having livestock in it. I keep the ammonia & Nitrites at 0,
and don't let the nitrates get over 10 or 12 mg/L. Usually less.
<Sounds like things are going/cycling well/as expected.>
Anyway, back to the crab - I got a ball Chaetomorpha, and 2 pounds of
live mineral mud from florida pets, and he must have hitched along with
that somewhere. He's about the size of a dime, including his legs, and
he moves sideways. He holds himself kind of like a boxing crab, but he
obviously doesn't have the coloring of one. He seems to prefer to dig
himself a pit under a rock or shell, that he can back into and hide, and
he's about the color of the sand, so he's pretty well camouflaged. I've
seen him sorting through the sand, I assume looking for food. Also, a
friend gave me some Hikari "crab cuisine" she had for her turtle, and
this little guy eats those with great relish.
<Hmmm... crabs are notoriously difficult to ID (especially from photos).
It looks like some kind of Mithrax or Xanthiidae crab to me.>
Of note, maybe, is that he only has a claw on the left side (hopefully
the photos show it kind of clearly). I don't know if that's because he's
a lefty by genetics, or by chance. I haven't had him long enough for a
molt, so it's hard to say for sure.
<It's most likely he lost the right claw in a fight or in the
journey/shipment from wherever he/she is from. It should grow back with
time.>
His tankmates include: 1 coral banded shrimp, about 15 hermit crabs
(dwarf yellow tipped, and red-legged), a tiny frag of a yellow
gorgonian, Nassarius snails, keyhole limpets, a small Aiptasia anemone
(keeping a close eye on that one), and a feather duster worm.
I'd like to know what this crab is, so I can keep him alive, happy, and
out of trouble (and everyone else safe, if appropriate).
<Unfortunately, I can't honestly tell you much for sure. But given
his/her overall appearance and your noted observations, my GUESS is that
he's your typical scavenger/picker. If you want to keep him, I'd just
keep feeding him what you're feeding him. Sometimes even the "bad" crabs
can be kept more or less "well behaved" if they're a relatively smaller
species and if you keep them well fed so that they don't have to start
getting aggressive/adventurous for food.>
Thanks very much in advance,
-Heidi
<De nada,
Sara M.> |
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Mystery Crab ID:
Huenia spp. – 12/20/07
Hey Crew! *waves*
<Hi Christopher! *waves back*>
I wrote to you about a week or two ago, but unfortunately never received
a response or was able to find one on your site.
<Oh, I’m so sorry!>
So I'll try again :)
<We'll try again!>
First off, you'll be happy to know that I removed the porcupine, dog
face, and clown trigger from my 55 gallon tank and brought them back to
the LFS.
<Yay!>
Now have 2 perc clowns, 1 yellow tang, and 4 Chromis. Whewph glad
someone pointed that out for me about overstocking! My LFS seems to be
more interested in $$$$ than :) Everyone in the tank seems really happy
now, thanks :)
<Great to hear.>
Now to get back to my question, the one I couldn't find a response for.
I found a crab who was a hitchhiker in my tank and am super curious what
he is!
<He's a neat little crab, that's what!>
He's lime green, quite small, and seems to have what looks like a plant
for a head.
<Heee, like in that commercial where people have flowers growing out of
their head?>
I'm attaching a picture. If you can provide any info or a link to read
on what he is it would be much appreciated. I cannot find anything! (Try
typing in crab with plant for head, it doesn't work well) hehe.
<LOL I bet that was interesting! What you have is an algal commensal
called Huenia heraldica, commonly called an arrowhead, Caulerpa, or
Halimeda crab. Please see these links for more information/photo
comparison:
http://www.wetwebmedia.com/marine/inverts/arthropoda/crabs/swcrabs.htm
About two thirds of the way down the page at this next link - and would
you look at that...one appears to have Halimeda growing out of its head!
It’s a Halimeda hat!
http://www.starfish.ch/collection/spidercrabs.html >
Thanks again!
<You're most welcome!>
#1 Fan Christopher
<Woohoo! Thanks! -Lynn>
Re: Mystery Crab ID:
Huenia spp. – 12/20/07
<Hi Christopher!>
Wow you're good! I'm impressed! Thanks sooooooo much!
<Well, we can both thank Bob for that one! I knew I’d seen that little
guy before, and sure enough I had – at WWM!>
Have a great day and hope the holidays go well for you and yours :)
And Merry Christmas if that's ok to say :)
<It's absolutely ok to say, and I thank you very much! A very Merry
Christmas and a Happy New Year to you and yours as well :-)>
Christopher
<Lynn>
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White Spot Mystery Crab…not
enough information – 12/17/07
Hey crew!
<Hey there!>
I was thinking of getting a hairy legged crab that my LFS has for my 30 gal.
FOWLR tank. When I researched him he is said to be peaceful.
<Which species?>
He does have the white spot markings on his leg that the "white spot crab" has.
<The closest thing I can find to a “White Spot Crab” is a hermit crab, Dardanus
megistos, commonly called a “White Spotted Crab”. This species does have hairy
legs, but I’m not sure if this is the crab you’re referring to.>
Are they the same crab? Or has my LFS perhaps misnamed him?
<Sorry, but based on the information given, I have no way of knowing. I don’t
know which species you’re referring to, and have no photos/knowledge of the one
at your LFS.>
Because when I looked the white spot crab up, it says it will eat smaller fish.
<Then I’d err on the side of caution and choose a more suitable addition.
Otherwise, you might end up with a COWLR instead of a FOWLR!>
Any help is appreciated.
<Happy to help. Good on you for researching before bringing home! Good luck
-Lynn>
Florida Crab
ID, need more information – 12/17/07
<Hi Grant, Lynn here this evening.>
I was wondering if you could help me identify this crab?
<Will sure try!>
I got my live rock off Florida and sent up to Alaska where I live.
<Yowza, that’s a long trip!>
I've had the rock and the tank setup for about 5 months now and I've
never seen this crab until the last couple days, making me think it
either was in egg form or else very, very, very, small when it arrived
at my place.
<Likely very small. Crabs hatch into a larval/planktonic form that
wouldn’t stand much of a chance outside a specialized system.>
The rock was left in a 40 degree Fahrenheit warehouse for at least 12
hours before alerting me it had arrived,
<Yikes!>
I figured most everything on it was dead, in fact there were plenty of
dead crabs and snails and such in the bottom of the bags and I saw no
life besides macro algae. The crab kind of looks like an emerald Mithrax
crab on its "back end". In other words, all of its legs except its two
front pinchers are covered in a fine hair/algae type looking material.
However, this one is stark white and it's shell is different. If you're
familiar with the Dungeness crab in Alaskan waters,
<Heeee! I live outside of Seattle, so I’m very familiar with those -
yum!>
that is what the shell reminds me of. A lot broader in the front end
than the back. It would be like taking a Mithrax crab, looking down on
it from the top and stretching the front out about 20% on each side. And
bleaching it white :) Hope you can figure out what type of crab this is
for me!
<I sure wish I could! Unfortunately, I can’t see enough of it in the
photo to be much help. What I’d like to do is refer you to some links
for comparison/more information. This first link has some great
information on crabs in general/ID help:
http://www.reefkeeping.com/issues/2003-12/rs/index.php
See the photos at this link, along with other “Galleries” linked at the
top:
http://www.nhm.org/guana/bvi-invt/bvi-surv/crab-g06.htm
This final link is a good site for identifying critters, etc, on Florida
rock. Scroll to #47 “Crustacean: Unknown White Crab”. It doesn't list
the species, but it’s from Florida and it’s stark white. See if it looks
familiar:
http://www.tampabaysaltwater.com/thepackage/organisms.html>
Sorry for the quality of the pictures, this guy hides a lot (obvious
since I haven't seen him in 5 months) and I've only recently noticed him
when I feed.
<Believe me, I understand. I’ve had a small (genus: Lissocarcinus) crab
hiding in my tank for over a year and I’ve never been able to photograph
it. Even with the best photos, ID’ing can still be an uphill battle.
There are a lot of crab species out there! Most times you’re doing well
to narrow it down to family!>
If they are too low quality, I can upload the much bigger file size
originals.
<Sorry, but in this case (since that little crab is so camera shy!), I
think the best thing to do is check out those links listed above and try
to narrow things down a bit. By the way, most crabs are opportunistic
omnivores, so depending on what you have in your tank, you might want to
keep an eye out for any problems down the road. That’s especially true
if/when it gets larger!>
I read your site all the time, this is the first time I've felt the need
to ask my own question though :)
<Well, hey, welcome to WWM! Please let us know if there’s anything else
we can do for you :-)>
Grant
<Take care -Lynn> |
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Crabs and Nudi/Slug?
Crab and Sea Slug Issues: Removal and Id - 12/10/07
Good morning/afternoon,
<Good morning, David!>
I've done a little digging around in your website on this matter and it seems as
though the general consensus when it comes to 'unidentified' crabs... is guilty
until proven innocent. <Agreed>
Here's my situation, My latest piece of live rock has pockets and holes galore
and I wouldn't be surprised if it actually had a fairly large hollow chamber in
the middle. I have noticed at a minimum, 5 different crabs, and at least 3
different species living on this single piece of liverock that is a mere 5lbs.
<Crab central!> This is a 90 gallon salt tank with the following inhabitants:
3" Kole Tang <Will appreciate a larger/longer tank in the near future!>
1.5" Yellow Tailed Blue Damsel
2x Yellowheaded Jawfish cohabitating in the same burrow
1 large Coral Banded Shrimp
Tuxedo Urchin
Both blue and red legged hermits
1 Large brown black-banded serpent star
Soft Coral Polyps
Other unidentified soft corals (pictures are coming and I'll take some time to
identify them myself if I can).
<Okay>
Back to the crabs... there is one HUGE crab in the mix.
<Uh-oh. Did you Qt/cure the rock separately? That’s a good time to check/remove
any unwanted pests.>
The main body is easily the size of my thumb from my 1st knuckle to thumb tip
(approaching 2"). It's a glossy black with sandy/brown legs. There are at least
two others of the same species that are much smaller in size. Furthermore, I
have seen two smaller dead crabs of this species.
<Not too surprising – could be resulting from too much competition for
food/territory, were preyed upon by other crab(s)/hermits/CBS, etc, or could
have simply fallen victim to transport/water condition issues.>
This large crab is of my primary concern.
<My immediate one as well.>
I have only witnessed the crab using its claws to apparently feed off the
liverock or the encrusted algae on it. As well, I coulda sworn it was eating
some hair algae.
<”See, I’m a nice little crab! I’m just eating this bit of hair algae - that is,
until you go to bed tonight, hehehe!”>
I've tried to catch the crab on 3 occasions but this fella is quick.
<Yep, they have to be to survive!>
I was afraid that it would prey on my fish, especially the smaller Jawfish
<Understandable/valid concern.>
or my damsel. However, just the other day the damsel was aggressively posturing
towards this larger crab driving it back into a hole in the rock. The crab had
every opportunity to reach out with it's claws and grab the fish... I think it
was big enough to do so.
<Those scrappy little Damsels! They're not easily intimidated, and indeed take
on individuals many times their own size. I've had them come after me when I've
gotten too close to their territory in the wild. LOL I have to admit, it's
pretty funny seeing them having a little fishy hissy fit - that is, until one
darts out and bites you!>
I'm hoping to remove it and introduce it to Mr Snowflake Moray in my other
tank...
however this porous liverock piece has some soft corals and feather dusters
growing on it. <Murphy's law.> I don't want to freshwater dip the rock. Would
you be of the same opinion that I should still work towards getting these varied
crabs.. Especially this big black brute out?
<Absolutely. There are several critter traps available on the market, but you
might try the jar method first. This is particularly handy since crabs can’t
climb glass. Just take the jar, lean it up against “Crab central” and partially
bury it in the sand to secure in place. Put a stinky piece of shrimp/similar in
the bottom of the jar. You may want to place/wedge some rock rubble around the
mouth of the jar to keep the hermits/CBS out! This method is best done at
night/after lights are out, and although it can take some patience, usually
works.>
I also happened to notice what appeared to be a very tiny crab... that swam
across my tank. <Wheeeee!> I couldn't believe my eyes... It looked beige with
red spots on it. It was no larger than the size of a pencil eraser. Any ideas?
<Was Tequila involved? Sorry, couldn't resist! I need photos/more info for a
glimmer of hope at an Id.>
Lastly, I noticed something strange in my coral polyps.
<Any apparent damage to the coral?>
It looked like a worm of some sort and I thought it best be removed... so I did.
Upon
further investigation I'm thinking it's either a tiny Nudibranch or a sea
slug/cucumber of some sort?
<Likely an Opisthobranch/sea slug instead of a Holothuroid/cuke).>
It's under an inch long, brown with two antennae's at the head. The back has a
number of tufts almost resembling tiny feather dusters and the underside is
whitish kind of
like a snake belly.
<Yep, that confirms it.>
I placed him in my 200gallon tank
<Is this a fish only system? It’s always possible that this little sea slug is
of the coral eating variety, so if you have any in that tank - bad news. I would
remove it.>
and immediately both my Magnificent Foxface and my Harlequin Tuskfish approached
it as a food item and made a hasty retreat.
<I bet!>
Nudibranch?
<Definitely sounds like an Opisthobranch of some variety. Please see the
following links for more info re:
http://www.wetwebmedia.com/seaslugsopisthobranchs.htm (opisthobranchs)
http://www.wetwebmedia.com/nudibran.htm (nudis)
http://www.seaslugforum.net/ >
David Brynlund
<Take care -Lynn>
Re: Crab and Sea Slug Issues: Removal and
Id - 12/10/07
Excellent, you guys/gals are awesome!
<Thank you David, it was a pleasure!>
I was just setting up my tank and the new piece of liverock went in without
(hahahaha, ya right) any critters (that I was aware of).
<Heee! They were hiding, and plotting, within that rock!>
I also had a mantis shrimp from the other piece of new liverock but luckily was
able to catch the critter quite easily within about 5mins.
<Excellent>
He stayed nice and still for me and then climbed into a small piece of live rock
which was easily put into a bucket...
<That’s something you don’t read every day! Mantis shrimp have extraordinary
eyesight and can be a challenge to catch/trap.>
Once in the bucket he swam around... Anyhow, I think I will try the jar method
for sure. It is a very nice looking crab... Glossy black with a reddish tinge to
it. Looks like King Kong compared to the other crabs.
<Heeee - King Crab!>
This rock is positioned over both the jawfishes who share a lair. <Yikes!> I
think the
opportunity was certainly there should he wanted to have preyed on them.
<Yes, although he might have, later on, after the more readily accessible food
was gone. I’m glad you’re getting him out of there.>
As well, the Coral Banded Shrimp and this brute have been side by side without
harassing each other.
<Yep, that’s a fairly good size crab. I doubt the CBS would have a go at him. As
for the reverse, they’d most likely get along fine until the crab saw the shrimp
as a threat to his territory/food supply - or if he saw an opportunity when the
shrimp was molting/vulnerable.>
Even still, I'd sleep better at night with AT LEAST this guy out and into my
200g tank....
<Understandable, though I’d still keep an eye out for trouble as he grows. That
is, if he doesn’t get eaten first!>
David Brynlund
<Take care -Lynn>
Help ID'ing a
crab: Need more detail - 12/10/07
Hi guys.
<Hi Michael>
I'll start off by saying how much I enjoy your site, it's by far the
most comprehensive aquarium keeping site on the net. Keep up the great
work!!
<Thank you!!>
I need some help ID'ing a crab that I recently found in my tank. He's a
whitish, grey colour with small hairs on his legs. He has red/orange
arms with a set of purple pinchers. Any ideas guys?
<Sorry, but without additional photos/detail, I'm unable to narrow it
down. I’d need to see the top view of the carapace/shell, and the legs.
Even then, it could be a challenge! I can, however, refer you to several
sites that should help:
http://www.wetwebmedia.com/marine/inverts/arthropoda/crabs/swcrabs.htm
http://www.reefkeeping.com/issues/2003-12/rs/index.php
http://www.nio.res.in/crab/crabs/tex2.html >
Does he pose any danger to my reef system?
<Potentially, yes, because most crabs are omnivorous and opportunistic.>
I've enclosed a picture of the crab in question (sorry for the crap
image quality, even the best camera phones leave a lot to be desired)
<Hey, not bad for a camera phone(!) but in these cases more detail, with
multiple angles, would be needed.>
Thanks for reading. Any info you can give me would be more than
appreciated.
<You’re very welcome. I just wish I could have been more help!>
Michael Mclaughlin
<Take care -Lynn> Re: Help ID'ing a crab -
12/11/07
<Hi Michael!>
Thank you for taking the time to answer my question.
<My pleasure.>
The sites you pointed me towards were a great help and narrowed it down quite a
bit.
<Excellent!>
I wish I could provide more pictures, but he's very skittish and seldom comes
out of his hole. I actually had to entice him out with a piece of squid.
<That’s good to know when/if you need to trap him!>
Anyway, here's a few more details about him. He has a trapezoidal shaped body,
which makes me think it's possibly a type of Grapsid crab?
<Quite possibly, yes.>
The colour is a very light grey almost white with small hairs. He also has faint
vertical maroon brown stripes on his body and legs.
<Pretty little crab :-) I wish I could be more specific with an Id, but
considering the number of species out there, I think you’re doing well to narrow
it down to a Grapsid. What’s important is that most crabs are not to be trusted
long term in a reef tank, so I'd either keep a very sharp eye on him/his
tankmates, or trap and relocate.>
Once again, thanks for the knowledgeable insight!!
<You’re most welcome!>
You guys rock!!
<Woo-hoo! Thanks, Michael!>
Michael
<Take care -Lynn> |
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