Please visit our Sponsors
FAQs on Chiton Identification 2

Related Articles: Chitons, Mollusks, Sea Slugs,

Related FAQs: Chiton ID 1 Chiton ID 3, Chiton ID 4, & Chitons 1, Chitons 2, & FAQs on: Chiton Behavior, Chiton Compatibility, Chiton Selection, Chiton Systems, Chiton Feeding, Chiton Disease, Chiton Reproduction & Mollusks, Sea Slugs, Sea Slugs, Marine Snails 1, Marine Snails 2, Marine Snails 3,

ID Help    4/7/12
I was observing my tank at night and saw this little guy.  I could not get a very good picture, so I tried to draw the distinguishing features of it.
I first thought maybe a Nudibranch, but the outside circle part seems to be one whole piece rather than feathery gills.  The markings on the outside circle are a little more random than what I drew... and I only barely noticed the two dots on the front, which was also the direction he moved.
And it moved VERY slow.  Not so slow that I didn't notice it moving, but slower than a snail.  It is slightly less than a centimeter in length. 
The outside bit is flat and the inside circle was double the thickness or more.
I saw nothing like a snails antenna, and the two dots I assume are the eyes are flat against what I assume is it's head.
<The description and picture both resemble a Chiton; a harmless hitchhiker.
The usual tell-tale sign of a Chiton are eight segmented plates though some species may have internal or diminished plates. Read more here-
http://www.wetwebmedia.com/chitonfaqs.htm >
<Quite welcome>

Re: ID Help 4/7/12
Yes!  That's it exactly!  Thanks.
<Glad I could help. Jordan>

Need help with a hitchhiker id 1/8/12
I need help identifying this critter I found grazing in my tank. It only comes out when the lights are off. My lfs said my live rock was sourced from Vanuatu and currently the only other live stock in the tank is my clean up crew (2 Astrea snails, 2 Cerith snails, 2 Nassarius snails, and 2 margarita snails). Thank you for the help.
<Appears to be a Chiton. Please read here:
and the linked Polyplacophoran files above. Bob Fenner>

HELP! This creature is eating my corals! 5/27/2011
I don't know if this is a Nudibranch or something else,
<The latter... A Chiton, Polyplacophoran. See here: http://wetwebmedia.com/chitonidf.htm
but I found it
attached to my sun coral two nights ago and the sun coral doesn't look very good now.
<Mmm, don't eat such, but perhaps just cruising about...>
When I tried to remove it, I expected it to be soft but it wasn't.
It had a hard structure - not like a shell but maybe a bone structure.
<Has shell plates...>
It was really stuck to the coral too. I had seen it in the aquarium previously but never attached to any of my corals. My red slime algae problem has reduced significantly o I was hoping the creature was eating it. It is small and oval when not extended. It stretches to at least 4 times its normal size. It was hiding inside the hole in the rock below the sun coral and stretching up through a hole at the top. It came out of the hole last night and moved (I have no idea where yet) and I snapped the picture then. Sorry they aren't better pics - I think I was too close.
<Likely so... w/in your lens' focus field/distance>
Should I transfer this thing to my fish only tank or dispose of it?
<I'd keep it>
Or was it just going after red slime algae which sometimes grows on the edges of this coral?
<Likely so>
Thanks so much for your help.
<Read re Tubastrea, here: http://wetwebmedia.com/dendrodisfaqs.htm
and the linked files above. These Dendrophylliids need some special care (each polyp feeding)... but can be kept. Bob Fenner>

Critter ID: Chiton -- 3/16/11
Greetings crew
<Greetings Ray, Lynn here today.>
Found this little guy under a small rock on my sand bed when cleaning the tank. No idea on what it is and it's the first time seeing anything like it. It looks like a pill bug that you would find in your garden. Fairly mobile. Hard shell.
<It's a harmless, mostly nocturnal herbivore known as a Polyplacophoran, or Chiton. For more information, please start here: http://www.wetwebmedia.com/chitonidf.htm
More here: http://wetwebmediaforum.com/showthread.php?293-Critter-of-the-Week-Chitons!&daysprune=-1 >
Reef safe?
<It depends on how you define the term but if you're asking if it's safe around corals, shrimps, fishes and the like, then yes, it's safe.>
Sitting in my QT tank now, and seems to be happy on its little rock, but if it is safe I would like to return it home.
<No worries, I'd go ahead and put it back in the tank.>
<You're very welcome.>
<Take care, Lynn Z>

A Chiton, I Believe: Yes Indeed! 11/24/09
Dear WWM
<Hello Chris, Lynn here this evening.>
Thank you for your continued dedication to educating those less knowledgeable than yourselves.
<You're most welcome; it's truly a pleasure and privilege to be able to share information with fellow hobbyists such as yourself. The thing is, we're all still learning whether we've been in the hobby three days or thirty years!>
I wanted to drop you this email to share the picture taken following newly spotting this critter in my reef tank in case you have a use for it. Nice to see new stuff even after 18 months!
<Live rock is the gift that keeps on giving!>
From your fantastic resource, I am reasonably confident it is a Chiton
<You're absolutely right.>
..and, hopefully, safe
<Yep. These guys are harmless herbivorous grazers of hard surfaces and mostly nocturnal, so enjoy!>
..(good job as I resisted the urge to go into defensive mode and pull it out until I knew what it was).
<Good thinking!>
Please correct me if the ID is wrong and feel free to use the image (sorry it's not any better) if you think it is useful.
<Thank you, Chris. The photo is more than sufficient to confirm the ID. Please see WWM for more information regarding these neat little creatures, starting here: http://www.wetwebmedia.com/chitonidf.htm >
Kind regards, Chris
<Take care, LynnZ>

Worm ID Please -- Friend or Foe? That's No Worm! That's a Chiton: Friend! 7/21/09
Hi Guys
<Hi Jim, Lynn here this morning.>
Great site!
I have found most answers to my queries on your web site but I can't identify this little chap. Can you help?
<I sure can. What you're seeing is a grazing Chiton/Polyplacophoran. They're harmless/beneficial, nocturnal, herbivorous grazers of hard surfaces. Please see the following links for more information:
http://www.wetwebmedia.com/chitonidf.htm (also see associated links at the top)>
<You're very welcome.>
<Take care, LynnZ>

What do you think these are? Chiton plates -- 7/18/09
Hello Guys and Gals,
<Hello Andrew, Lynn here tonight.>
I just wonder if you might be able to shed some light on this subject for me?
<Hope so!>
My reef tank has been up for almost 4 years now, and over this space of time I have been finding these (pictured) items through the tank. Now to my untrained eye they appear to be a beak of some sort, but I have no triggers or beaked stock in my tank!
<They're not beaks!>
I'm sorry I couldn't get clearer pictures, but my pokey little digital was struggling to get these images.
<No worries, your photos are just fine.>
To me, they look like tiny little turtle beaks. The funny thing is, they appear to be in pristine condition, with no rounding of any of the sharp edges (some of which are very fine) that you would expect to see of any item that's been rolling round the ocean floor for any length of time. My second thought was that they may be coming from a piece of crumbling rock, but all my rock is as hard in appearance as the day I put it in the tank. My substrate is crushed aragonite, and has not been anywhere near a real beach in hundreds if not thousands of years I suspect. Which brings me to my actual question! What do you think these might be? Turtle beaks?
<Nope, they're the remains of a Chiton/Polyplacophoran (or several). What you're seeing are the individual plates ('valves') that when the animal was alive, overlapped each other along the dorsal/top surface of the animal. Chiton plates are surrounded and held in place by a leathery band called a girdle. Once the animal dies, the soft tissue and girdle decompose, leaving behind 8 hard plates. At some point you must have had at least one Chiton in your tank but unfortunately it/they didn't make it. You may still have others though! For more information on these neat little creatures, please see the following links:
I know octopus beaks look a little like these, but are softer. These specimens seem to be made up of the same stuff as human teeth (they clink when tapped on glass).
<I always try to avoid that!>
Over the years, I've pulled roughly 8-10 of them out of my tank, in varying sizes (most just like these) and would love to know what they are!!
<Chiton plates!>
Thank you for your time.
<It was a pleasure!>
Andrew B
<Take care, LynnZ>

Re: What do you think these are? Chiton plates -- 7/19/09
<Hey Andrew!>
Oh good lord, I never would have thought of that!
<That's completely understandable. I only know because I've seen them before.>
A quick Google image search showed exactly what you already knew.
<What we both know now!>
I can't believe how some of life's mysteries seem so logical when you know the answer!
<Too true!>
As you state, I did indeed have Chitons in my tank at one time, and a rather large one at that, though I would never have made that connection in a million years!
<Well, the good news is that if anyone ever asks you about those, you'll know exactly what they are! The overall look and shape is distinctive.>
Thanks so much for your help.
<You're very welcome.>
I'm almost a little embarrassed
<Well, I can assure you, knowing what those things are puts me right square in the middle of fish-nerd territory so don't be embarrassed, be glad!>
<Take care, LynnZ>

Help with ID: Probably a Chiton - Cryptochiton stelleri -- 5/28/09
Dear WWM-Crew,
<Hello Alex, Lynn here today.>
I have a question regarding the identification of an unknown object that has been found floating close to the shore in California. It has been posted on a German website for identification and apparently left all users without a clue. I thought that maybe one of you has seen something like it before and can help. Picture can be found here: http://www.meerwasser-lexikon.de/was_ist_kxMXbrrcbg . According to the finder the object felt leathery on the outside and softer on the inside.
<My guess is that it's the Polyplacophoran/Chiton 'Cryptochiton stelleri', a known California species. Unlike most other Chitons, this sizeable species doesn't have any visible plates on the dorsal surface. They're all enclosed under a reddish to brown leathery hide known as the 'mantle'. What I can see of the underneath portion also supports this ID. That is, a thick girdle/perimeter surrounding an elongate, light-colored foot. According to the following link, these animals had a bit of a hard time in the 1990's, possibly due to disease. Apparently they were decomposing and washing up on shore with a blotchy appearance, which sure does describe the look of the one photographed. Please see the following links for photos and more information:
http://www.wallawalla.edu/academics/departments/biology/rosario/inverts/ Mollusca/Polyplacophora/Cryptochiton_stelleri.html
Blotchy appearance discussed here: http://www.wallawalla.edu/academics/departments/biology/rosario/ inverts/Mollusca/Polyplacophora/Cryptochiton_stelleri.html#Underside
Another photo showing a blotchy individual:
Good photo showing foot, girdle, etc:
http://upload.wikimedia.org/wikipedia/commons/b/b4/Cryptochiton_stelleri_underside.jpg >
Any help would be appreciated.
<Sure thing, hope that helps!>
Best regards, Alex
<Take care, LynnZ>


Re: Help with ID: Probably Cryptochiton stelleri -- 5/28/09
<Hi Alex!>
That's great, Lynn!
I have posted a short German summary (with a reference to you and WWM) as well as your answer in the original at the link I submitted earlier.
<That's great, thanks. The query should be available at the dailies sometime in the next day or so, then archived in the FAQ's.>
Thank you,
<You're very welcome. It was my pleasure.>
I really was at a loss and every time I saw the photograph I wondered what it might be.
<Heeheee! I laughed the first time I saw it because I thought it looked like a baked ham stuffed with fois gras, studded with cloves - blech!>
I thought that it was a mollusk but had no idea where to start searching as it was different from any I have seen so far
<Yep, they're such odd looking creatures that unless you'd seen one before, you'd be hard-pressed to tell it was a Chiton.>
..and obviously the Seaslug forum was the wrong place to search. ;-)
<Actually, there is a section there that covers Chitons, because they're commonly mistaken for sea slugs! Here's the link: http://www.seaslugforum.net/factsheet.cfm?base=chitons >
Thank you so much! Alex
<Again, it was a pleasure. Take care, LynnZ>

Strange Slug Creatures in Marine Tank 05/21/09
I hope you can help me by identifying two creatures I have adopted. The photos I am attaching are of two creatures; one I queried with Bob F about a year ago and have only just captured a picture of it, and the other is of a strange creature I have just found on the underside of the rock a chili coral is attached to that I have just purchased.
<I can't tell what this is because the powerhead is hiding most of it, sorry. Please try to send a better pic.>
Hope you can ID them for me. The one in the plastic bag is the one I have just unwillingly purchased, which I will be taking back tomorrow if it is unsuitable for my reef tank.
<The one in the bag looks like a Chiton. Please see here:
Thank you
Sara M.>

Re: Strange Slug Creatures in Marine Tank 05/21/09
Hi Sara
I also forgot to ask will the Chiton eat only nuisance algae or will it eat my lovely leafy algae as well?
< I doubt it will eat your leafy algae... they feed more on algae, bryozoans, diatoms and such that grow on surfaces.>
Thanks again
Sara M.>

Re: Strange Slug Creatures in Marine Tank 05/21/09
Hi Sara
Thanks for replying so rapidly I may keep the Chiton now I know it is safe. Its quite an interesting little thing. I have attached the only pictures I have of the other. I suppose I could have moved the powerhead but I didn't want to disturb it. I haven't seen it for around a year now, but I was still interested to know what it was.
<I'm sorry, but I honestly can't ID it from those photos. Obviously, it's a Mollusca of some sort... that's about all I can tell.>
The last two pictures are of what looks to me like some kind of pink and green anemone; this disappears into the rocks by day. Could you shed any light on this please.
<This looks like a Majano anemone to me.
Thanks again.
<De nada,
Sara M.>

Are These Baby Turbo Snails? Chitons and Mystery Critter -- 5/15/09
WWM Crew:
<Hello, Jesse>
I recently had an outbreak of Asterina starfish in my reef tank so I've been paying close attention to my rock work and removing them as I see them.
<Not fun. Most of the time those little guys are harmless but if/when you get too many or if you get a variety with a taste for your favorite coral - yikes!>
While on starfish patrol I noticed an abundance of small (ant sized) creatures I haven't seen on my rock work before. I removed a few and photographed them...see attached.
<I see, thanks.>
They appear to be snail like, having a protective shell and a soft gooey body.
<Hmmmm, crunchy on the outside, gooey in the middle. Sounds like a Baby Ruth bar! Actually, what you have are harmless and beneficial little critters commonly called Chitons, or more specifically, Polyplacophorans. This particular variety is one I have in my tanks and has never caused any problems. They're herbivorous grazers of hard surfaces, stay small, and apparently reproduce quite readily in captivity. All in all, they're a welcome addition to a reef tank. Here's a photo of several of mine for comparison (these are about 3mm long): http://bb.wetwebmedia.com/gallery/pic.php?mode=large&pic_id=126 . For more information on Chitons, please see the following WWM links, starting here: http://www.wetwebmedia.com/chitonfaqs.htm
http://bb.wetwebmedia.com/viewtopic.php?f=25&t=298&p=3108#p3108 >
I've also noticed that almost all of the 3-7mm sized snails in my tank have white spots/growths on their shells. I have also attached a picture of this but it's of poor quality.
<I'm sorry, but I can't see the subjects well enough to be able to determine what anything is. If you could take one out and get a more detailed photo that would be super. If you could get photos from several angles, including the opening it would be even better!>
Also, these creatures only come out at night,
<If you mean the Chitons, that's completely normal.>
..the same time as the baby snails with the spots on them. What do you think these creatures are, and are they a threat to my reef tank?
<I doubt it, but it's always nice to be able to confirm that. Have you noticed any sort of damage/sign of trouble? Do try to get some additional photos of these critters and we'll see if we can't figure out what they are.>
Thank you in advance,
<You're very welcome. I look forward to solving the remaining snail mystery!>
<Take care, LynnZ>

Crustacean ID 4/27/2009
I have been Googling all over the place to try to identify a sort of strange crustacean I came across today.
I'm not sure if you can help with identification and if so can I send you a photo?
<Sure. Please get shots from a few different angles. Do keep the image size to a few hundred kilobytes or less.>
If not, could you point me in the direction of someone who might?
<You may want to give this page, as well as the links on the top of this page a look:
http://www.wetwebmedia.com/marine/inverts/arthropoda/crustace.htm >
Many thanks
<My pleasure>
Re: Crustacean ID 4/27/2009

Thanks Mike
<Hi Marisa, my pleasure>
I carried on Googling and eventually identified it as a giant Chiton / Dinoplax Gigas.
I'd never seen anything like it before and thought maybe it was an alien / living prehistoric creature / stone come to life,
<In a way, it sort of is.>
so I just had to make sure.
Thanks anyway!
<No Problem>

Nudi/Worm ID? 10/6/08 Hello Everyone at WWM! <Art> Yet again I find that I need some advice, or, at least an ID of some sort... A few days ago I found this creature crawling around my 55 Gallon Reef Tank. I looked up the worm FAQ and had no luck. Whatever this thing is, it seems to be sensitive to light. If I have the lights off and shine a light on it, it quickly retracts into wherever it is anchored to. Another thing is, I've never seen it in it's entirety. So it could be a few inches long, or ...? The top of it has several "openings" <"Polyplacophora"> I guess you could call them, but I haven't been able to keep it in the open long enough to see if they actually open. It's kinda freaking me out. I was thinking a Nudibranch of some sort, but it looks like nothing in your 6 or so Nudibranch ID pages. Please help! I appreciate any info you can give me! -Art Perez <Is a Chiton... not harmful. Please read here: http://wetwebmedia.com/chitonidf.htm Bob Fenner>

Become a Sponsor Features:
Daily FAQs FW Daily FAQs SW Pix of the Day FW Pix of the Day New On WWM
Helpful Links Hobbyist Forum Calendars Admin Index Cover Images
Featured Sponsors: