The Case of the Unknown Chiton

[tripsied]

After doing some work on my tank's flow rate (I have a Perfecto 75 gallon Jetstream, a topic will be appearing in the General forum shortly on this if you want to know more) and wound up having to move a lot of rock.

Along the way, I discovered ( 8O 8O 8O ) that there is a (possibly multiple) chiton (pronounced KY-ton or CHY-ton ???) in my tank. I haven't a clue where the beastie came from--but whatever the case--it's in there.

Here's where things get a little weird. My particular chiton looks relatively similar to other pictures I have seen of chitons, no big deal, right? Well, this little guy doesn't seem to have the girdle that the others (though it could have been camoflaged (spelling??)) do AND it COLOR MORPHS!!!! 8O 8O 8O like a cuttle fish or a chameleon. It did, I swear it did! It was on the underside of a piece of rock, which was kind of pinkish, it crawled up the rock and came to a green patch, where the buggy turned green, then over a piece of brownish rock and it turned brownish! I know, I saw it do it, I have a 3 year old for a witness! :lol: :lol: :lol: It eventually disappeared into the sand bed, which being whiteish (or at least USED to be), it (you guessed it) turned whiteish, aka the color of the sand. Very bizarre thing indeed.

In all the articles I have read thus far (it's really not all that many, so don't be overly impressed just yet), none of them mention color morphing.

I said all that crapola above to ask this: Is this a known behavior for chitons or do I have "sumpin' " other than a chiton? If it is a chiton, any guess on what one? A vague descrition: it looks like a cross between a trilobite and a pillbug. Can't really tell ya what color it was, because the color changed! It did seem to have sever diamond (possibly) shaped lines on its back; moved rather slow (like chitons do).

Does Mr. Brandt have a comment or suggestion per chance? :lol: Or possibly SeaMaiden? Or anyonelese for that matter (Jon and SeaMaiden seem to be the best at "Name That Bug"! :lol: :lol: :lol: )

Thanks for any input, it's greatly appreciated. I will try and hunt down that little bugger and see if I can get a picture of it.

BTW, anyone know how to get the thing off the rock wihout hurting it? (This is not one of those "Pinch Your Puffer" questions 8O :lol: ) So I can get it into something that I can photograph it in?

 

[Anonymous]

It's very tough to remove (KY-tons) from rocks, especially if they're small. Best bet is to snag it when it's moving from one rock to another...

FWIW, I have never witnessed any of our chitons on or in the sandbed, and I've certainly never seen them color change rapidly.

You may want to search under the general category of Polyplacophora, the class that chitons are in. My book tells me 4 genera of tropical chitons, Acanthopleura, Tonicia, Chiton, and Cryptoplax; you may want to google images for those also.

 

[Anonymous]

Another strange thing...you're saying you don't see the girdle, but that's the only part that's flesh. The plates are just shell, so I don't see how they could change color. Does it have eight plates? Count carefully, because there is usually a very small one near the head.

 

[Anonymous]

I really wonder if you have something other than a chiton. I was cruising through my little invert book, and I found this creature, a type of polychaete called a polynoid worm. It can change color to match its host. This particular species is an obligate commensal of sea cucumbers, but there are other species. Anyway, it looks like a pillbug-trilobite cross like you described.

Gastrolepidia clavigera

And another species, Lepidonotus sp.

 

[John_Brandt]

Ok, you guys have me captived. I want to know about this creature. Please provide a picture, ASAP. Chitons tend to find a niche they like to "sleep" in when they aren't feeding. It may be very near the last spot you saw it. These things will arrive on live rock and can remain unnoticed for years.

Tripsied, how fast does this thing move (inches/minute or seconds, etc). How fast does it change color to match it's surroundings? As it passes from one color to another does the color change coincide perfectly with the substrate? IOW, when the animal is halfway on brown and half on white substrate, is its coloration half/half too? Please elaborate on these diamond-shaped lines.

Matt, interesting info about the worm changing color to match the host. Does it simply match the color of its host wherever it's found, or will it change color in real time? IOW, if you pulled this worm off of a brown soft coral and placed it on a Caulerpa blade would it turn green right in front of your eyes?

 

[hdtran]

In my opinion, by the way, Chitons (chitons?) are perfectly harmless molluscs (mollusks?). So, please don't remove it from the rock, but maybe move the rock closer to the glass so you can take a picture.

That poor harmless chiton was probably just hanging out in the ocean, when some diver yanked the rock from the ocean, to your tank... I guess I'm just a softie...

Hy

 

[tripsied]

Matt,

The lepidonotus looks almost exactly like what I saw. It was definitely one of the weirder moments around the tank! hee hee. I googled all of the species you mentioned and they are definitely NOT what I saw in the tank, besides, most of the chitons listed seem to come from South Africa and I have nothing in the tank that even remotely comes from that region. Would that make sense?

I did, however, collect some reef rubble from a beach in Panama, though the rubble sat in the open air for 4 or 5 days, took a plane rise and then sat downstair for several more days. Could it have come from Panama?

Since the tank still is "snowing" from all the particulates, I am going to go on a "hunt" for this thing and see if I can find it.

John,
It changed color pretty much in real-time, though it seemed to lag for a bit though, i.e. when it changed from pinkish to green, it took about a second for it to do so, though I am not quite sure, I was quite startled by its its being and the color change.

As to its motion, it was rather on the slow side and kind of seemed to "meander" (if that's a decent term to use) its way into the sand, (I kept moving the rock to see it better) rather than the "OMG I need to get out of here!" kind of attitude (I hope that makes sense)

As to the lines, there were some feather duster skeletons underneath it, so it may have been mimicking that pattern.

Found a link some of you may find interesting (enough worms in there to give ya the creepin' heebie-jeebies for months! hee hee )

http://www.calacademy.org/research/izg/

Well, I'm off to go "hunting", I'll post some pics, provided I can find the darn thing...could be anywhere. (A 75 G tank isn't all that big until you're looking for a half-inch worm!! LOL)

 

[tripsied]

Found this on that link above

What up with dat?

8O 8O 8O 8O 8O 8O 8O 8O 8O 8O 8O 8O 8O 8O

Hee hee...I think I'll go look for the "whatever it is" now!

 

[John_Brandt]

when it changed from pinkish to green, it took about a second for it to do so

8O

 

[John_Brandt]

What up with dat?

I can't figure out if it's a little starfish that grew a big ole leg, or a big ole leg that grew a little starfish

 

[Anonymous]

Well, chitons come from just about everywhere, not just S. Africa. There are coldwater and tropical species worldwide, AFAIK. They are almost always an intertidal species, though, and this is why the fact that yours went in the sandbed surprised me.

John, I just don't know. The book only said that the species could match the color of its host.

tripsied,
There is one very easy, very definitive way to verify if you have a chiton or not. All chitons have 8 plates on their back. If it doesn't, it's not a chiton.

 

[tripsied]

I went searching for it last night and wouldn't ya know it my camera is not working (I guess the trip through the jungles of Panama was a little rougher than I thought).

I was not able to lcate the critter in question. At some point, most likely this weekend I am going to be purchasing some more live rock, when I do that, I will be re-arranging things, so I can do a better search, get a working camera and post findings.

 

[tripsied]

I went to the LFS and got some new rock and while rearranging things in the tank, I found the critter in question.

It does have the 8 plates that Matt was talking about. It is tan to pink in color and about 1 to 1.5 inches in length. I am not sure as to the color morphing, it may have been the light (or my surprise). I have it tucked in a filter box with some sand and rock if any questions need answering.

I bet that it is a chiton, the only thing is, is that there is no visible girdle on it. All the other chiton photos I saw had a visible girdle, this one doesn't. I apologize for the lack of pics but my camera is non-functional. I am trying to get my hands on one so I can photograph it.

Late Edition:

I found this pic at http://nighthawk.tricity.wsu.edu/museum ... _Show.html

It looks EXACTLY like the critter in question