Trachyphyllia boring shrimp/crab - Page 2

aquanut6 · #26 07/11/2007, 10:57 AM

Fliger, I bet that would work...do you know of a site/place to get Interceptor?

sjfishguy · #27 07/11/2007, 03:25 PM

Why can't you try freshwater dipping? I know everytime I fresh water dip something crustaceans of all sizes shoot out immediately. Since we are talking LPS, I think they could handle it.

AIMFish · #28 07/11/2007, 11:13 PM

Interesting crab. It reminds me of the immobile hermits that I've seen, actually found one once, but they are all pictured living in old tubeworm holes. The soft curled end of the body is very hermit like. I don't frequent the other invertebrates section much but perhaps a crab specialist does?

rharr21 · #29 07/11/2007, 11:47 PM

Can I use a likeness of that monster in the next "Scary Movie".

aquanut6 · #30 07/12/2007, 07:33 AM

Rich, I'll try that first. Btw, I owe you a frag. I'll send you a PM.

aquanut6 · #31 09/14/2007, 10:42 AM

Well, I tried the freshwater dip to no avail.

Check out this crab I found on a friends wellso. This was a brave f$%^er. He was truly outside of his hole on top of the wellso trying to grab/fight anything that came his way including the tongs I caught him with...

GoingPostal · #32 09/15/2007, 03:40 PM

I believe these may be what's living in my candy canes. There are holes in between the heads and something living in it, I can only see claws. I've dipped in freshwater, iodine dips and can't get them to come out. Does anyone think it would be safe to cut in the skeleton and dig them out? They irritate some of the candys and the other's seem fine with it but I don't want them spreading to my other lps, especially the brains.

aquanut6 · #33 09/15/2007, 03:58 PM

From my experience, that would be fine GoingPostal. I've had a favia, an acan, and a wellso that I just dug into the hole with a small tipped screwdriver smashing the crabs that were in there. All corals survived and thrived afterward...

LeslieH · #34 12/17/2007, 02:15 PM

Hi everyone -- I just was searching for posts with 'gall crab" and found this one. Louis - that was a gall crab you had. There are quite a few different types with very different body shapes. Some look like regular crabs while others are quite bizarre. I think yours is in the family Cryptochiridae which has 41 species in the tropical Pacific. Aquanut6's first one appears to be another species of gall crab while his second one is a hermit crab. Judging by the curled soft abdomen that's a normal hermit that somehow lost it's shell & was looking for a new home.

Even though the common name is "gall crab" not all of them form galls; many just have open holes. They are obligate commensals & can't live anywhere else. Scubajsm's info is correct. they don't really harm the corals as the corals grown around them to form the holes & galls. They eat coral mucus and/or filter feed. Many help keep the corals clean & the more mobile of them help fend off coral predators. In some, the females are restricted to the galls while the males which are smaller can slip in & out.

The crustacean curator at my museum is quite interested in these crabs & would love to get specimens for a study. There's a pinned message in the Other Invertebrates Forum which explains how to preserve & send crabs if anyone would like to contribute specimens.

Rothie · #35 12/17/2007, 02:36 PM

Leslie-
I'd like to thank you for the enlightening info you have provided.I'm sure that many "gall crabs" will rest easier tonight!

aquanut6 · #36 12/17/2007, 04:19 PM

Leslie, that is great information. However, I'd have to differ about the 'gall crab' that was in my acan as the tissue around the hole was continuing to recede. After removing it from the acan, it has thrived much more than it did with the crab. I remember reading somewhere that not all gall crabs were safe but that the majority of them were no threat to the corals.

LeslieH · #37 12/17/2007, 05:05 PM

You could certainly be right. There aren't many people working on life history/ behavior of these crabs so not much is known about the majority of species. At least one species keeps a circle of a bare space around its hole in order to cultivate filamentous algae which it eats. While it doesn't affect the coral any more than that I'm sure a reefer wouldn't like the appearance. It would be great if people who have them would make a few notes about their behavior or feeding & then send them to us for id. That would add a lot of useful information to our knowledge of these interesting crabs.

nUgZ · #38 12/17/2007, 05:31 PM

I've had one of those crabs in a couple different Acans. I don't have any pics of the crabs, but here is one where you can see the damage. If you look at the top left portion of this pic you can see where detritus has settled in the hole.

MinibowMatt · #39 12/17/2007, 05:46 PM

I just found a dead one like in the OP's pic. It was almost 3/8" diameter, and all curled up. I thought it was a hermit without its shell, but now I think it was a gall crab... Uggghh

aquanut6 · #40 12/17/2007, 07:07 PM

Leslie, if I come across another one, which I'm pretty sure I will at some point, I'll be sure to send it off to you after observing it's behavior as I'd be more than happy to contribute ever growing knowledge base of our hobby...

louist · #41 12/17/2007, 08:04 PM

Leslie, thank you for ID'ng this guy, the guys from the Museum of Victoria (Australia) haven't got back to me. I suspect they prioritise Christmas over gall-crabs

I never saw the 2 crabs leave the Trachyphyllia that they live in. However, this piece used to be in a larger tank and thus close observation wasn't possible. That said, this Trachyphyllia never extended its polyps for feeding in the 2.5 months I had it, despite my best efforts. After the removal of the 2 crabs, it extends its polyps 24/7. I have suspicions that mine might not have been commensal, but this is based on my limited observations.

Perhaps a comparison of the anatomy of the mouth parts and pincers might yield further clues to the different species' behaviours?

Lastly, I don't want my thread to turn people into gun-ho invert terminators. There are many inverts that make their homes in the corals that we purchase so perhaps people should think twice before conducting prophylactic fresh water dips on all purchases.

PS. Leslie, if you want to use the photos I posted for educational illustrations, let me know and I'll send you some high-res versions.

LeslieH · #42 12/17/2007, 11:15 PM

Louis - I'd love high-res versions, that would be great. Please send them to lharris(at)nhm(dot)org

I sent your images to Roy Kropp, an expert on cryptochirids and the author of this article which applies to your area - http://rmbr.nus.edu.sg/rbz/biblio/42/42rbz521-538.pdf He can't tell what it is because of the algae & debris on the crab's back. Interesting enough, he can't find previous records of any gall crab on Trachyphyllia.

Morphological studies do help, as do stomach analysis. In the case of the one I mentioned above a stomach analysis proved it ate the algae it farmed.

I agree with you completely Louis. We don't know the interactions of most of the inverts we see and many turn out to be beneficial or even necessary in reef ecosystems. Besides, if you look at them without bias they're fascinating. It's a shame to judge them guilty without evidence.