FAQs on Chiton Identification
Related Articles: Chitons, Mollusks, Sea Slugs,
Chiton ID 3,
Chiton ID 4, &
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,
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
The usual tell-tale sign of a Chiton are eight segmented plates
though some species may have internal or diminished plates. Read
|Re: ID Help
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!
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
When I tried to remove it, I expected it to be soft but it
It had a hard structure - not like a shell but maybe a bone
<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
<Likely so... w/in your lens' focus field/distance>
Should I transfer this thing to my fish only tank or dispose of
<I'd keep it>
Or was it just going after red slime algae which sometimes grows
on the edges of this coral?
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
Critter ID: Chiton -- 3/16/11
<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
<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
<You're very welcome.>
<Take care, Lynn Z>
A Chiton, I Believe: Yes Indeed! 11/24/09
<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
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
<Live rock is the gift that keeps on giving!>
From your fantastic resource, I am reasonably confident it is a
<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).
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
<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:
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 Jim, Lynn here this morning.>
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:
(also see associated links at the top)>
<You're very welcome.>
<Take care, LynnZ>
What do you think these are? Chiton plates --
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?
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
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!!
Thank you for your time.
<It was a pleasure!>
<Take care, LynnZ>
|Re: What do you think these are?
Chiton plates -- 7/19/09
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
<What we both know now!>
I can't believe how some of life's mysteries seem so
logical when you know the answer!
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
<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:
Blotchy appearance discussed here:
Another photo showing a blotchy individual:
Good photo showing foot, girdle, etc:
Any help would be appreciated.
<Sure thing, hope that helps!>
Best regards, Alex
<Take care, LynnZ>
Re: Help with ID: Probably Cryptochiton stelleri --
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
<That's great, thanks. The query should be available at the
dailies sometime in the next day or so, then archived in the
<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 -
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
..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:
Thank you so much! Alex
<Again, it was a pleasure. Take care, LynnZ>
|Strange Slug Creatures in Marine Tank
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
<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:
Re: Strange Slug Creatures in Marine
Tank 05/21/09Re: Strange Slug Creatures in Marine Tank
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 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.
Are These Baby Turbo Snails? Chitons and Mystery
Critter -- 5/15/09
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):
. For more information on Chitons, please see the following WWM
links, starting here: http://www.wetwebmedia.com/chitonfaqs.htm
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
..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
<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:
Re: Crustacean ID 4/27/2009
<Hi Marisa, my pleasure>
I carried on Googling and eventually identified it as a giant Chiton /
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.
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