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FAQs about Limpet Snails, Acmaeidae, Fissurellidae and more, Scutus, Stomatella
Identification 2

Related Articles: Gastropods, Sea Slugs, Mollusks, Abalone,

Related FAQs: Limpets 1, Limpets 2, Limpets 3, Limpets 4, & Limpet Identification 1, Limpet Behavior, Limpet Compatibility, Limpet Selection, Limpet Systems, Limpet Feeding, Limpet Disease, Limpet Reproduction, & Marine Snails 1, Marine Snails 2, Marine Snails 3, Marine Snails 4, Snail ID 1, Snail ID 2, Snail Behavior, Snail Selection, Snail Compatibility, Snail Systems, Snail Feeding, Snail Disease, Snail Reproduction, Mollusks, Sea Slugs, Abalone,

Stomatella or Scutus?       11/21/17
Hello wet web crew,
<Hey KL!>
I have looked over your site and read all your limpet and snail ID threads.
My main tank is 200 gallons with 75 refugium. Currently it only has crustaceans and soft corals in it. Mainly mushrooms and a toadstool.
I found this critter in my tank tonight and wondering what it is.
Looks like a snail but only a small shell. Is it a snail or a limpet?
What species?
<Yikes... due to striations on the shell, and that it isn't white... will guess a Stomatellid; but... could be either>
It's about 1 3/4 inch to 2 inches.
<The shell? Most Scutus top out at 12.5 mm>
Is it friend or foe?
<Friend; purposeful algae scraper>
I'm wondering if it felt safe to come out because there are no fish currently in the tank.
<Likely arose from your live rock; common>
It moves pretty fast for a snail. I also have video if you want me to send it.
It's shell seems frilled or scalloped along the edges and I can't really tell if its black or a translucent shell.
<Good points. Stomatellids typically have a mantle "tail" and are not emarginated>
Thank you for any help you can offer.
<I'd keep it. Cheers, Bob Fenner>

What is this?     1/7/14
I found this eating my star polyps.
Any idea what they are?
<Ah yes; Limpets... see WWM re. Bob Fenner>

What are these? Likely Stomatellid - 1/29/13
Something eating my Zoas. I did find a sundial snail,
<Yikes, definitely remove it and keep an eye out for others.>
…but I have these slugs with a bluish back also. Should I yank ‘em?
<Hmm, well I’d need to see the top of the snail to be sure, but it appears to be a harmless, Stomatella sp. of some sort.  I would definitely leave any of these in place as they’re beneficial herbivorous grazers that reproduce easily in captivity. For more information, please enter the term “Stomatellid” in our search engine: http://www.wetwebmedia.com/Googlesearch.htm 
More info here: http://wetwebmediaforum.com/showthread.php?176-Critter-of-the-Week-Stomatella-nails&highlight=stomatellid 
Hope that helps! Take care, Lynn Z>

Snail I.D    12/26/12
I recently found this little mollusk crawling through my tank. As I was unsure of what it was. I removed it from the tank for now. It is about an inch long, flat(ish), and has a girdle of (skin or whatever) around it. No hard outer shell is apparent but has two feelers at its head. Please help.
<Mmm, there is a shell, internally... this appears to be a Scutus... see here:
A harmless limpet. Bob Fenner>

Re: Snail I.D   12/27/12
Thank you very much. Added the guy back to the tank.
<Ah good. BobF>

Keyhole limpet    6/8/12
Hi Crew, I had a pair of keyhole limpets
<The Ca. coast species, Megathura crenulata? In a chilled system?>
 for 2-3 years and they died about 6 months apart. That was about 6 months ago. I had babies that were smaller very tiny and the largest smaller than a split pea. They are slowly getting larger. But lately I found really tiny ones and am wondering how that could be. Are they so small when first hatched that I would not notice them till now? Sam
<Mmm, yes... but I suspect what you're seeing is something else... another similar appearing "limpet" sort of snail. Bob Fenner>

Help! Is this a turbo snail hitchhiker?   4/25/12
Hi there,
<Hi Rowan>
 I've just introduced 2 turbo snails, 2 hermit crabs (one of which seems to have died) and a sea urchin to my tank with my two clownfish. Today I noticed one of my turbo snails seem to have a little hitchhiker on the underside of its shell. The creature looks like another snail consisting of a shell which it lifts every so often to poke out what seems to be antennae
and occasionally it's mouth. I was lucky enough to get a fairly clear picture which I have attached. Can you ID this creature? Should I be worried about it? Does it need removing? I'm particularly fond of this turbo snail and would be sorry to see it harmed.
<It appears to be a Limpet; a beneficial algae grazer. Read more here--
http://www.wetwebmedia.com/LimpetID1.htm >
Many thanks,
<Quite welcome>

Can you ID this creature? 7/16/11
Let me preface by saying how wonderful you guys are! I own a reef store in Las Vegas and tell everyone to check out the site.
<Ah, good to both>
I have a customer who brought me this cute little bug and would like to know if he can keep him in his reef or not.
<Is a Limpet of some sort/species and should be fine w/ most all one might have in a reef system>
His shell is hard and has the appearance of a scallop in shape but it is more like a snail. In the second pic you can see his little antenna sticking out from under his shell. Thanks in advance.
<Please see here: http://wetwebmedia.com/LimpetID1.htm
and here: http://wetwebmedia.com/LimpetCompF.htm
Bob Fenner>

unknown snail ? 7/15/11
Hello to the crew,
<Howdy Rich>
One of the main problems with identifying unknowns is not knowing what to search under, and running blind yields literally millions of hits... so I'm hopeful that someone within the crew will be able to point me in the right direction (please). This shelled development of my tank was discovered during the recent tank move. They appear to be only under the substrate (of course I don't get a chance to night view for any length of time) and measures about 1cm across at it's widest point. Sorry about the quality of the side shot, but at least it's profile is discernible. Any ideas of it's identity?
I thank you for your assistance,
Richard J.C.
<Mmm, would like to see the inside of the shell of a dead specimen, but I think this may be a member of the Slipper Shells, genus Crepidula, a calyptraeid. Bob Fenner>

Unknown slug? 10/19/10
I am new to the salt water hobby. I started my JBJ 24 gallon Nano cube approximately 6 weeks ago. 20 lbs. of live sand and about 22 lbs. of live rock. I started my initial cycle with three damsel fishes. Last water check at the LFS showed everything within acceptable parameters and I am well on my way to completing the cycle.
Over the last couple of days I noticed first one, then three light brown slug type creatures who come out only at night when all the lights are off.
last night I tried to grab one with the tweezers and it broke itself in half, one half went in my dish and the other swam away and hid. This morning, I located another, carefully removed it and have attached the
photos to send to you.
It seems to be light brown in color with two long feeler type projections at the front with two small stubby points in between. it appears to have two black eyes at the front also with a very small tube (mouth) off to the left. When it moves, the rear appears to form two points, so from the top it kind of looks as though it is pushing with the two back end pads.
I do not have any corals or invertebrates yet but plan on purchasing these soon.
Should it stay or should it go?
<I'd leave it/them be... This is some sort of snail/gastropod... likely related to Scutus, a limpet... family Fissurellidae...>
Thanks - Roxane
<Welcome. Bob Fenner>

Nice pic!

Re: Unidentified Goby, and Scutus... 5/5/10
Bob and Marco,
That looks pretty spot-on (Eviota queenslandica) for a photo match. I'll certainly let you know if he ever exceeds 2.4cm. :)
Thanks and kind regards,
PS: I got another stowaway from the same batch of live rock, too. I noticed this (a Scutus antipodes?) getting around the QT tonight (must ask the LFS where they're getting their live rock from)...
<Ah yes. Quite common. Good pix, ID. BobF>

Unknown Organism: Fleshy Limpet: Lucapina sp. -- 4/6/10
Hello WWM,
<Hello JM, Lynn here today.>
Attached, please find a couple of photos of an organism I have not been able to identify at WWM or elsewhere.
<What you have is commonly called a 'Fleshy Limpet', a species of Lucapina in the Family: Fissurellidae. Basically, it's a Keyhole Limpet that's able to extend its soft tissue mantle over the entire external surface of the shell instead of just skirting the outside edges.>
It is a little bigger than a quarter and always stays on the live-rock.
<Yes, they seem to prefer hard surfaces -- rockwork, glass, and such.>
It moves frequently but very slowly.
Any information or links regarding ID, origin and tankmate compatibility would be much appreciated.
<Lucapina spp. mostly hail from the Western Atlantic, from Florida all the way to Brazil, and the Caribbean. They seem to be omnivorous, mostly grazing microalgae as well as small sessile invertebrates from the rocks (sponges, hydroids, etc.). However, I have read about, and seen photos of, some individuals consuming coral tissue. It's not a given that this will happen with your individual, though, especially if you have a mature system with a lot of microalgae, etc., on which it can feed. Many hobbyists have kept these, in systems with corals, with no problems. Personally, I'd go with an innocent until proven guilty theory and leave in place until/unless I saw damage, but it's up to you. For more information, please see the FAQ about half-way down the following link titled 'Orange Frilly Limpet - Lucapina aegis': http://wetwebmedia.com/LimpetID1.htm
The individual shown looks very much like yours, but unfortunately, I can't find any other corroborating photos on the web, or in my reference books, to positively confirm that what you have is Lucapina aegis. Don't get me wrong, I'm not disputing what Anthony Calfo has stated at all. I'm just not personally comfortable offering a solid ID on a snail without having seen the actual shell under the mantle, knowing where the snail came from, and having multiple sources to back up the ID. Complicating matters is the fact that these guys can vary in mantle and shell color to a surprising degree. The only thing I'm sure of is that you have a species of Lucapina. Is it Lucapina aegis? It could very well be. What's important to note is that in Mr. Calfo's response, he recommends removing this snail, but again, it's up to you. Here's a link that reportedly shows a live specimen of Lucapina aegis (mantle not fully extended): http://www.jaxshells.org/aegis1.htm
Several live specimens shown at the bottom of this page (the last one 'may be Lucapina aegis'): http://z14.invisionfree.com/Conchologist_Forum/index.php?s=3d4adb02ec7886bb7914cf50fad8f838&showtopic=984&st=0&#last
Dr. Shimek's article (see Fleshy Limpet section about 2/3 way down the page: http://www.reefkeeping.com/issues/2004-06/rs/index.php
More FAQs at WWM: http://wetwebmedia.com/LimpetID2.htm
Thanks in advance!
<You're very welcome!>
<Take care, LynnZ>

Re: Unknown Organism: Fleshy Limpet: Lucapina sp. -- 4/6/10
<Hi, JM!>
Thanks so much for that awesome and comprehensive response!!
<You're very welcome, it was a pleasure!>
I haven't noticed any bad behavior towards the rest of the ecosystem so I am glad to say he stays.
<Yep, why not give the little fellow a chance? You can always remove it later on if it starts nibbling on things it shouldn't. In the meantime, you've got a nice little algae-grazer and addition to the biodiversity of your system.>
Thank again,
<Take care, LynnZ>

Cap Snail ID: Batman is a Scutus! 4/5/10
<Hi Chris, Lynn here today.>
I have a cap snail in my tank that has doubled in size since first noticing it about 4 months ago.
<That's a happy snail!>
It has been a joy watching it cruise the tank. We call him "Batman".
<Heeee! Love the name!>
My question is "Can you identify it from the attached photo and if so, how big will it get?"
<I sure can. 'Batman' is a species of Scutus, aka a Ducksbill Limpet, Elephant Slug, etc., in the Family Fissurellidae (Keyhole and Slit Limpets). They're mostly algal grazers but apparently some do eat sponges. All in all, they're beneficial/welcome additions to a reef system. Regarding size, it depends on the species, but most have the potential to get up to around 2' in length. There's a species from Australia and New Zealand though (Scutus antipodes), that can reach 5' in length. Now that's a big snail! For more information, please see the following link: http://www.seaslugforum.net/factsheet.cfm?base=scutus >
Thanks in advance,
<You're very welcome, enjoy Batman!>
<Take care, LynnZ>

10/02/10 Dead Chitons.. No, Limpets!
Hi Simon,
<Hello Beth, how are you?>
My aquariums are doing fine at the moment, thanks to you.
<That's great news!>
Still having a few minor problems with alkalinity and calcium but I am giving it one more water change before I try to address that problem, again.
<Ok. Keep referring to the chemist-man RHF and you should make it through!>
Right now, I am finding dead Chitons in the 20g tank. My big 1 1/2" Chiton is now just an empty shell and this past Sunday I found another Chiton clinging to a rock with what looked like a mucus net surrounding it.
<These are Limpets, not Chitons. They have a conical shell and some have a hole on the top. Chitons are segmented.>
Could the mucus be a defensive mechanism of the Chiton or is it what killed the Chiton?
<This has probably come from the Limpet itself when it died. Did you not think you had a predator of these somewhere?>
It was Super Bowl Sunday and I promised my dad I would watch it with him so I snapped a couple of pictures and ran out the door. When I came home the next day, I found the empty shell of the Chiton lying in the sand.
Any clue as to what is happening to the Chitons?
<I'm sorry Beth, apart from a predator and/ or water chemistry I have no idea. Remember that these need balanced calcium & alkalinity to build their shells. If these have been 'off' for some time, on top of the other
problems that you have had, then that could easily explain their deaths.
Maybe it has all just been 'too much'. Do be sure to test to make sure that you do not end up with a 'cascade' effect that affects your other creatures>
Thank You for your help,
<No problem at all>

Help Me Identify This Snail: Stomatellid -- 1/26/10
<Hello Nick, Lynn here today.>
I discovered this little guy crawling around the back corner of my tank last night.
Any ideas on what it is and where it came from.
<It's a pretty little Stomatellid (probably Stomatella varia) that most likely originated in the Western Pacific. They're common, harmless/beneficial herbivorous grazers in the family Trochidae. For more information, please see the following links: http://bb.wetwebmedia.com/viewtopic.php?f=25&t=181
Be sure to Google WWM for a veritable boatload of FAQ's re: http://www.wetwebmedia.com/Googlesearch.htm
Photos of Stomatella varia: http://www.gastropods.com/2/Shell_2422.shtml  >
I had never seen it before. Thanks for all the info and service you all provide.
<You're very welcome and thank you!>
<Take care, LynnZ>

Help with identifying unknown snail?? Invert., SW... 1/25/10
<Hello Blaire, Lynn here today.>
I've had my aquarium for about 6 months now. About 2 months ago I bought some live rock from someone who was parting out their tank. Needless to say I brought in all sorts of new life forms.
There were a bunch of tiny pretty snails, pods, bristleworms, even some neat looking mini anemones I couldn't identify that my Klein's has since ate. (They weren't Aiptasia). There's one thing I can't seem to identify though. It's about 3/4", slightly more oblong than round, and very dark blue in color. If the light isn't directly on it, it looks black. It does not have an actual hard shell, and I can only say "snail" because it has a snail's head with antennas. The "shell" is soft and flexible (like the body of a ray), and it is very slow moving. I can't really get a pic of it as I only see it a couple times a week and it's always between rocks, never out in the open. Any help you can give me would be greatly appreciated!
<Hmmm, there are many possibilities. An animal with antennae but no visible shell could be some sort of sea slug, Nudibranch, Polyclad flatworm, or even a Scutus unguis (aka the 'Ducksbill Limpet'). Soft and ray-like sounds more like a flatworm or some sort of slug or Nudibranch, rather than a Scutus spp. but it's worth looking into. Scutus unguis actually has a white shell, but it's usually covered by the animal's deep black mantle. It's possible that under certain lighting, the flexible black mantle could appear bluish. I'm sorry I can't be more helpful but there are just too many possibilities. Here are some links that will hopefully help narrow things down a bit.
Nudibranchs: http://www.wetwebmedia.com/nudibran.htm
Sea Slugs: http://www.wetwebmedia.com/seaslugsopisthobranchs.htm
Polyclad Flatworms (see Pseudoceros sapphrinus): http://www.wetwebmedia.com/WormPIX/FlatwormPIX/Flatworms2.htm
Scutus Unguis: http://www.seaslugforum.net/showall/scutus
Please let me know if you need any additional help. I know a picture sounds impossible, but if you get lucky, send it along!>
Thank you, Blaire
<You're very welcome. Take care, LynnZ>
Re: Help with identifying unknown snail?? Scutus Unguis - 1/25/10
Hi Lynn,
<Hi Blaire.>
Thank you so much for your help!
<You're welcome!>
I looked it up and it's a Duckbill Limpet.
<Neat little creatures.>
All the little life forms that pop up are such treasures and I make it a
point to find out what they are and what their needs are. Maybe you could answer one more question for me? I have a Harlequin shrimp (what a beauty!) and would like to know if there is anything I could add to my tank that would dispose of the leftovers of the starfish he eats? I've asked my LFS guys and they say my clean up crew should take care of it but they don't. These little white pieces are adding up quick and I can't get to them to siphon them out. Any suggestions??
<If you don't already have hermits, I'd recommend getting some Nassarius snails. They're terrific little scavengers that stay hidden within the substrate then erupt en mass when they smell food. They also have the added advantage of stirring the sand up a bit as they move around. You could try either Nassarius vibex, a small species (usually less than 1/2") or the larger (up to ~1') Nassarius distortus, frequently called 'Super Tongan' Nassarius snails. Both are commonly available on the 'net and elsewhere. Avoid any snail sold as Nassarius obsoleta. It's actually Ilyanassa obsoleta, a smallish brown snail that comes from cooler waters and lives accelerated/shortened lives in the higher temperatures of our reef systems. Another possibility, if you already have hermits (and you like them), is to add a few more. I'm not a big fan because of their tendency to pick at beneficial sessile livestock/fauna, rob corals of food and occasionally kill snails but it's up to you. It just depends on what you want to keep. Please see the following links for photos of the various Nassarius species, as well as the Ilyanassa obsoleta snail that you'll want to avoid!
Nassarius vibex: http://www.gastropods.com/0/Shell_1930.shtml
Nassarius distortus: http://www.gastropods.com/9/Shell_3309.shtml
Ilyanassa obsoleta: http://www.gastropods.com/5/Shell_3305.shtml >
Thanks again, Blaire
<It was a pleasure. Take care, LynnZ>

Mollusk ID: It's The Incredible Mr. Limpet! -- 1/21/10
<Hello Beth, Lynn here today.>
I was wondering if you could help me figure out what this is.
<Fire away>
I have a 29 g tank that has been running for about 4 years. While I was doing a water change, I noticed this little guy on a conch shell (by the way my gold striped clown insists that the conch is his anemone).
<That's a clown for you!>
I was hoping you could tell me what this is.
<It's a pretty little Keyhole Limpet, family Fissurellidae. There are other similarly shaped Mollusks, but the hole at the apex/top is the clincher. This opening, which is used for expelling waste, can vary from round to distinctly keyhole shaped, hence the name. Also typical is the arrangement of concentric growth rings (often showing as different colors), along with the strong radiating ribs/ridges that extend from the shell's top/opening to the bottom edge. The almost rough surface can sometimes be obscured by a growth of algae (usually green or coralline), but doesn't harm the animal. The feathery-looking protrusions you see on the soft tissue mantle skirting the shell are called 'mantle tentacles', and are sensory in nature. These neat little creatures are for the most part harmless/beneficial herbivorous grazers but if the food supply runs low, they can occasionally move on to soft corals or large polyped stony corals. For example, I had Keyhole Limpets for years in my tanks with no problems until one large individual decided to munch on my favorite cherry red Blastomussa wellsi polyps -- aaahh! Needless to say, he was ejected from the display! That's the one and only problem I've ever had with Keyhole Limpets. Personally, I'd leave your little individual in place and enjoy it. For more information, please see the many WWM FAQ's regarding. Just Google the term Keyhole Limpet: http://www.wetwebmedia.com/Googlesearch.htm
Thanks so much for you help,
<You're very welcome. Enjoy Mr. Limpet!>
Beth Van Zandt
<Take care, LynnZ>

Baby snails...or something else? Probably something else. 1-17-10
I've noticed these little snails in my tank a few months ago. They were very small, just a tiny white dot. Now that they got to an acceptable size I want to know if you could help me identify them. <I can try!> I have a few Astrea snails in my tank and Nassarius Tonga and Vibex. These little snails spend all their time on the glass and don't hide during the day. What worries me is that it started with 3 and now I have at least 25. They don't seem to be bothering anything but I want to make sure they are safe. I included a pic I hope it is clear enough. <Unfortunately, no.> The biggest one I noticed the other day is probably 1/4 inch. Hope you can help. Thank you very much.( I read all the articles but could not find any positive ID). <I'm assuming your attached photo shows the underside of the animal attached to the glass. It doesn't look to be a snail at all. My best guess points to most likely a Chiton, or possibly a limpet. I can't give much other specifics without a better photo. Maybe Bob can chime in with his $.02.><<Do look like Limpets to me as well. RMF>>

Full size pic

Re Baby snails...or something else? Probably something else. 1/18/10
Thanks I know you tried your best. <You're very welcome. If you want to send another photo of the critters in question, we might be able to help out a bit more.> We took one out of the tank to examine it better. It has a
hard cone shaped shell, some shells are black and some are tan. The shell looks a little like a limpet like you said. <Limpets are highly variable in nature. That's the best I could come up with.> They have the 2 antennas that snails have and I can see their mouths grazing the glass just like my Astrea snails. Are all these common features of the limpets as well?
<Limpets do have antennae. I don't know too much about them other than what they look like, unfortunately. Based on your mouth and antenna description baby Stomatella snails are another possibility. Do enquire via
a Google image search.> Sorry I couldn't get a better picture. <Try, try again. Even out of the water might be insightful.> Thanks at least I know they are safe and wont harm anything. <Welcome. Matthew.>

Hoof limpet - 11/07/09
I have attached a picture of what I believe to be Hipponicidae sp. residing on the back of one of my snails!
<Looks like it!>
I have 'Googled' around and found some supporting information but wondered whether this was a true example of symbiosis
<Mmm, of a sort... I'd label this animal as a "space parasite"... as the "host" appears to be harmed to a degree, and definitely doesn't seem to benefit from the Limpet>
or just an accident. The forked proboscis (if that's the right term) extends significantly from the shell during feeding as it picks around the areas that the snail is grazing so I assume is diet is basically the same.
I not been able to narrow down to species level but suspect that it is a harmless hitchhiker as the 'host' seems to be unaffected.
<Mmm... I don't know... having something so large, heavy on ones shell...>
I found it interesting and have not seen any similar pictures on the web so wondered whether you would be interested too.
<Yes. Thank you for sharing>
Forgive my ignorance if it is actually common and I'm just bad at web searches but if it is unusual I can think of no better place to share it.
Your site has helped me a great deal over the years and continues to be my favourite reference as the reliability and accuracy of information here is in my humble opinion, above question.
Many Thanks,
<Welcome Chris! Bob Fenner>

Snails? Yep... Stomatella 10/4/09
I had purchased a lettuce Nudibranch for my algae that disappeared as fast as I put it in. I never saw it again. Then about a month later I saw TINY versions of something that are now this size. Are these offspring or some evil snail that must be removed.
Never saw these before I had that lettuce Nudibranch. They come out at night and do not like to be photographed. Sorry for the lame pics, this was the best I could do. I figured with enough pics you could help me to identify them. The 4th pic is sort of a HEAD ON view.
<Read here:
Bob Fenner>

Yellow Mobile Unknown Hitchhiker 9/10/09
I have a very colorful hitchhiker that showed up about 3 months ago. It was smaller than a pencil eraser at that time but over the months it has grown to about the size of a quarter. It does move around on the rocks,
not very fast but fast enough to make me look for him every morning and evening. He is circular and mostly flat, except in the center. Looks to be a mouth but I'm just guessing at that. I took a photo this evening and
as I was focusing, it spit out a white speck from the "supposed" mouth.
Is this something beneficial or is it harmful to my reef aquarium.
<More the former... I think this is the Limpet Lucapina aegis. Bob Fenner>
Thank You

Re: Yellow Mobile Unknown Hitchhiker 9/10/09
Hello Again,
<Waking up now!>
After months of looking for the name of this hitchhiker, I finally ask for assistance in identification and of course, in the meantime, I keep looking for the answer. I used a different search engine and different key words and I think that I found the id. Is the answer Keyhole Limpet?
Thank You,
<A different Limpet (Thrummmm!). BobF>

Re: Yellow Mobile Unknown Hitchhiker 9/10/09
Morning Bob,
<And you Beth>
Grab a cup of coffee and wake up.
<Am trying>
Just got your note, I am assuming the "different limpet" means that I have the wrong species?,
<Mmm, yes... but such are the dangers of common appellations>
I was going to go with Fleshy Limpet but the information I found states that these are Keyhole Limpets as well.
<"You say tomatoe"... Megathura is the genus of our (Calif.) Keyhole...>
However, the information also states that they are about the size of a shield limpet or smaller. I have a shield limpet and my yellow limpet is much bigger than the shield limpet.
Of course you could be stating that it is just a unusual looking limpet.
In which case, I totally agree.
I am getting conflicting information about limpets and cannot decide if they are beneficial or harmful. Do you have any thoughts about the benefits or harm that they can cause to coral and or live rock?
Thanks Again,
<... Please read on WWM re such Archaeogastropods.... BobF>

Re: Yellow Mobile Unknown Hitchhiker 9/10/09
Morning Bob,
Please ignore last post. I read your response to my second post and did not see your answer to my original inquiry until a few minutes ago. Yahoo sent it to my Spam folder.
<Velkommen! B>

Keyhole Limpet: Lucapina sp. -- 1/17/09
<Hello there!>
I am trying to identify this keyhole limpet. It came from Florida with an order from critters.
I can't find this particular one in any pictures.
<It appears to be what's commonly called a fleshy limpet, in the genus Lucapina (possibly Lucapina suffusa). Please see the photos at the following link for comparison:
I wanted to see if it is one of the bad ones.
<Fleshy limpets are not usually a problem in captive reef systems. I'd leave it in place and enjoy! For more information, please see the 'Limpets' section at the following link. The last paragraph specifically relates to Lucapina species. http://reefkeeping.com/issues/2004-06/rs/index.php >
Any help would be greatly appreciated.
<You're very welcome. Looks like you've got a gorgeous little limpet! Take care, Lynn>

Identify- Fleshy Slug AKA Fleshy Limpet 10/22/08 Hello crew... <Hello Jessy here> I am baffled by this ...shall I say....shell-less slug?? It moves all over the tank sometimes on the glass but usually on the rockwork. The first picture is very grainy but I wanted you to see it from the front also and this was the best I had. Thanks in advance for the help. <Donna, by my estimation that is a fleshy limpet. See here for further ID http://www.melevsreef.com/id/fleshy_limpet.html> Regards, Donna
<Regards, Jessy>

Reef Tank Newbie With Unknown Slug: Stomatella sp., Overcrowding Issues -- 8/27/08 Hi guys, <Hi there KC, Lynn here this afternoon.> I have a 34 gallon Solana cube that has been up and running for a little over three months now, one month of which was spent cycling. It has approximately two inches of live sand <Hmmm, please see this link for more information regarding sand bed depth: http://www.wetwebmedia.com/dsbdepth.htm> ..and about 30 pounds of live rock. I am running a 250w MH SunPod lamp 10 hours a day and have a CPR Bak Pak skimmer hanging off the side of the main display. I also have the stock skimmer doing whatever it thinks it is doing in the back sump. I wanted to move the CPR to the built-in sump, but found out that the pump would not fit back there because of the limited space even after removing the stock skimmer, <Yep, that's frustrating all right.> so I thought it wouldn't hurt to run both. <No, it could be redundant - but that's not always such a bad thing! If the stock skimmer isn't producing good skimmate (either in quality or quantity) you could try running without.> The water readings are: calcium -- 460 <Would let this fall a bit, to under 450. That is, assuming that the numbers here are correct (the test kit's reliable, not out of date). For more information regarding calcium, please see this link (as well as related links at the top): http://www.wetwebmedia.com/calcalkmar.htm> pH - 8.4 nitrate -- 0 phosphate - 0 alkalinity - (I use the Red Sea pH & Alk test kit and it doesn't give a specific number for this. It has a color chart that shows my water is in the "Normal Range - 1.7 - 2.8") <Not good -- you need specific numbers instead of a range. I personally use/prefer Salifert for KH/alkalinity testing. It's quick, easy to use, and most importantly, has a distinct color change for better/more reliable results.> These are the only things that I am testing for, should I be testing for more? <Other than listing salinity/specific gravity, what you have sounds fine to me. If you were having problems maintaining your calcium level, I'd recommend a magnesium test kit, but that doesn't seem to be necessary. Just keep in mind that if you ever do consider adding supplements such as iodine/iodide, magnesium, etc you'll need to first acquire those specific kits. It's important to get a base-line reading as well as monitor the levels as you increase them (not to mention making sure they stay within recommended range thereafter.> I am still new to this and am not too sure which elements I should be testing for. <You should be good to go. Just be sure to keep up with regular water changes. These make a big difference in helping to maintain the extra supplements I mentioned (and more).> For inhabitants, I have: 1 Fire Angel <I'm not familiar with this term. I'm guessing it's a Flame Angel (Centropyge loriculus)? If so, wow are they beautiful.> 1 Velvet Damsel 1 Three Stripe Damsel <These damsels can become *very* aggressive, especially in small/crowded systems such as this.> 1 Ocellaris Clown <Would be nice to have a pair, but at this stocking point, I wouldn't add one.> 1 Scooter Blenny 2 Fire Shrimp <These are truly beautiful shrimp, if a bit shy (especially in systems with strong lighting.> 1 feather duster <Can be difficult to keep.> 1 2" Tridacna crocea <I would not have added this until the tank was 6-12 months old at the very earliest.> 1 Turbo snail <Terrific herbivore.> 5 Margarita snails <Unfortunately, these are cooler water snails that don't live long in reef systems. The warmer water speeds up their metabolism. It's a case of 'the candle that burns twice as bright, burns half as long'.> 2 Cat Eye snails <These, plus the Turbo listed above, have big appetites and will need a lot of algae to survive. If there isn't a sufficient amount existing in the tank, they'll starve to death. You may need to supplement with dried seaweed/Nori sheets (available at most regular grocery stores and Asian markets).> 10 or so hermits <Hmmm, careful here. Hermits are neat, but many reef keepers (like me) choose to avoid them. They tend to be opportunistic little fellows that can cause trouble (picking at things, stealing food from corals, killing small snails, even fellow hermits). This is especially true when they're in high numbers, as is the case here. It just makes for more competition for food. Keeping them well fed, along with supplying plenty of (larger) empty shells, will help deter (but not necessarily prevent) unwelcome behavior.> 1 hammer coral 1 torch coral 1 small Acropora frag 1 plate coral a tiny patch of green star polyps that never come out <Watch out. If/when these do come out, they can spread and take over like you wouldn't believe. They'll even climb up the sides of your aquarium. It's best to keep these separate and away from your main rockwork so they can't spread and cause problems.> a small rocks with a few Zoanthids on it 2 red mushrooms <'Shrooms can also take over too, so watch them.> 4 other bluish mushrooms that were given to me and I don't know the names of. <Yikes, this is an overcrowded tank, especially considering the fact that it's only 3 months old! I would have skipped the Damsels, the Margarita snails, the two 'Cat eye' snails, the feather duster, clam, and at least 8 (or all) hermits. There's also a potential for serious trouble down the road with the various corals you've listed. In smallish systems such as this, you should really limit the variety of species to those that will get along best in the long run. Corals are like any other animal in that they'll fight to ensure their survival. They do this in a variety of ways, including chemical warfare or 'allelopathy' (for example many soft corals/Gorgonians), direct contact with either sweeper tentacles that sting (Euphyllids, like the hammer and torch coral you have are particularly notorious for this) or mesenterial filaments that digest the neighboring coral's tissues, or by simply overgrowing (for example: green star polyps). Be sure to keep enough space between the corals you have and move/remove as necessary. I'd give the torch and the hammer corals at least a 6" buffer zone all the way around them, and keep an eye on those green star polyps and mushrooms. Mushrooms (Actinodiscus), although seemingly harmless, can sting adjacent, less aggressive corals.> Each feeding, I soak the food in V3 Triple Strength. The food alternates between flake, Cyclops-eeze pellets, krill, and Mysis. For the corals, clam and feather duster, I dose DT's live marine phytoplankton once every other day, and dose Marine Snow once a week. <I'm not personally crazy about this last product, but hey if it works for you! Just be careful with these two additives and decrease if you notice excessive algae production.> Unfortunately, I bought basically every inhabitant in the tank before learning the error of buying prior to research, and am trying to keep them healthy and correct errors I have made. <Good for you.> Is my tank overcrowded? <Oh yeah.> When I bought all the equipment, sand, and rock, the LFS told me to cycle it for a month, which I did. Other than that, they happily sold me whatever I wanted and I admit that I lost a rose tip anemone and Nudibranch that they sold me not long after I bought them. <Oh no. What a shame.> It wasn't until that point that I started doing research on the internet about trying to keep the rest of the inhabitants alive. I didn't want to lose any of the remaining inhabitants and felt like a real jerk for losing what I did. <Well, we've all made mistakes in this hobby. I know I've made my share and then some! The important thing is that we learn from them. In your case, it sounds like you just trusted people that were either lacking in knowledgeable or that were more concerned with selling their livestock (or both). The good news is that now you know better. You know to always do your research *before* purchasing. That combined with quarantining new livestock will save many lives and much frustration.> That was when I stumbled across your guys' site and have learned TONS of invaluable information. <Excellent!> That was less than a week ago, and it has already saved my Zoanthids from Zoa-eating Nudi's. <Yikes!> I cannot thank you guys enough for your wisdom! <LOL While I would never doubt the wisdom of Bob or my fellow crew-members, the closest I personally come to being wise is wisecracking!> My question: I have had a couple of these slugs running around the tank and was not sure if it was harmful to a reef tank or my inhabitants. <Nope, not at all. They're absolutely harmless and beneficial.> I was wondering if you guys could ID it for me. <Yes we can. Oh, you want to know what it is! It's a species of Stomatella (possibly Stomatella varia), a commonly seen hitchhiker that reproduces readily in tanks and is frequently seen grazing film algae.> I tried to search through your guys' vast resources, but I could not find what this slug is, or if it is harmful to my reef tank. <No worries, it's a good guy.> I might have missed it though in the ID section, as I was trying to find it during work hours, but I was hoping you could give me a hand. <Sure thing. For more information on Stomatellid snails, please see the following link: http://bb.wetwebmedia.com/viewtopic.php?f=25&t=181 Be sure to also check out the many FAQ's regarding these neat little snails at WWM. Just go to our Google search engine, and enter the term Stomatella: http://www.wetwebmedia.com/WWMAdminSubWebIndex/question_page.htm > Thanks in advance, your site has really opened my eyes to aquariums and I would have no doubt lost everything in a matter of time if I didn't stumble across your Web site. Thanks again! KC <You're very welcome! Take care, -Lynn>
Flatworm Or Nudibranch... Or Maybe Not... (Not) -- 03/28/08 Hello guys, <<Adam>> I have an interesting creature in my tank, I've read through the forums and search across the Internet and I cannot get a positive ID on it (Even checked the sea slug site you guys listed as a resource.). <Okay>> It resembles a Nudibranch, although the one picture I found of something that resembles it, you guys ID'd it as a flat worm. (http://www.wetwebmedia.com/fltwmid.htm, second picture from the top, question titled Nudibranch or Flatworm.) <<Mmm, not a good picture is it? Regardless'¦what you have is NOT a flatworm>> Flat worms are generally not as large as this animal is, or at least I thought they weren't. <<Some do get large>> The guy is around 2 - 2.5" and only comes out at night, I have seen what seems to be "antennae" protruding from it. <<Yes>> I tried several different ways of taking the shot, one strictly with LED's, others with flashes and/or an LED flashlight. I have attached a few shots. <<I see them>> One peculiar thing I witnessed last night was a split in the animals back. <<Hee-hee! A clue!>> Down the center, which opened slightly and receded when I placed the light over him. Any ideas? <<Indeed'¦see below>> I am at a loss and don't know whether to enjoy the little guy or eject him. I monitored him for about an hour the other night when I saw him open up down the middle and never really saw him feeding on anything and he stays around a rock in the tank with Zoanthids, and a piece of orange Monti. Only thing I could guess is filter feeding or feeding off the worms and such in/on the rock. Thanks again, Adam <<Well Adam, I've seen a couple of these before. What you have there is Scutus antipodes (Black Limpet, Elephant Snail, etc.). The 'split' you saw is where the mantel parted (the mantel comes up from both sides to cover the shell on the animals back). This critter is reputed by some to be reef safe...others to be a Cnidarian muncher'¦but all seem to agree it's a good algae grazer and a prolific breeder. Regards, EricR>>

No text? 1/8/08 <See... Stomatella... BobF>

Re: ? Snail ID ayer 1/9/08 Bob - <Joel... Oh there you are!> My apologies. I don't know what happened to the content and subject line. I would not be so rude as to intentionally do such a thing. I wrote an email describing my tank setup and how much you and your crew have helped me get 6 months into the hobby with nary a problem that wasn't foreseen. Thanks for the response to what my question was - "any idea what these might be, perhaps some sort of Nudibranch?" I will read up on Stomatella now. Thank you again. Regards, Joel Pippin <Looked like S. varia to me. Cheers, BobF>

Black Slug... actually is a snail... Scutus spp 12/03/2007 I found this in my tank and thought I would share the photo. <Thank you for sharing!> I did some research and found the slug to be (Scutus sp.) <Actually is a snail, not a slug.> Order: VETIGASTROPODA Superfamily: FISSURELLOIDEA Family: Fissurellidae. <Yes, more here: http://www.seaslugforum.net/factsheet.cfm?base=scutus > Our slug is about 2 1/2 inches and may grow to 5 inches in length. This is a nocturnal slug and I found it by mistake a few weeks back. <Well you found it nonetheless.> Just wanted to share. <Thanks again!> Have a great day, Lis <Thanks Lis, you as well! Mich>

Well done Mich/Mitch... RMF.

Scutus pics 9/5/07 Hi, <Make me smile> If there are any Scutus fans out there, here are some fun pics I took of one of mine. :) Best, Sara <What did the Incredible Mr. Limpet say? Thrum!!! BobF>

Limpets A year ago I noticed two limpets in my aquarium. It is a 90 gallon (6'x1'x2'). My guess is they came in on the live rock I added 7 months before. The curious thing is this. It took 7 months to see the first 2, and I now have roughly 100 more. They are black with a white stripe on their back and are actually not unattractive despite their numbers. They do a good job keeping the glass, and everything else, clean. They range in size from 1/4 inch to 1 1/2 inch and are found everywhere from the skimmer collection cup (always a few small ones on the cup of a CPR Bak-Pak), to the live rock, to the glass. I have about 80 pounds of Fiji live rock, a 1 inch aragonite sand bed, the CPR, and a couple Hagen 802's for circulation. I also have Naso, yellow, and regal tangs (1 of each--all about 3.5 inches), a coral banded shrimp, a false percula clown, and about a dozen snails and small hermits. There are no corals or anemones. Ammonia and nitrites are 0. Nitrates are close to 50. S.G. is 1.024. Temp. is 76 and pH is 8.0. I add no chemicals and have 0 algae other than coralline which covers most everything and has to be scraped from my glass at least every two weeks. I have two questions. First, is this an extremely unusual occurrence? In order to identify these things I had to post pictures to a newsgroup since the few inexpensive books I have don't even mention them. Second, I'll be adding a dwarf lionfish and snowflake moray to the system tomorrow. Will either/both decide to make a feast out of the limpets? If they do, it would probably be good for them, since, in their numbers, I think the limpets would be able to sustain enough of a population to meet their dietary requirements. By the way, when I first set up this system roughly two years ago, I dosed Kalkwasser for about 2 months to try and get the coralline to grow, and it didn't. Ever since, I have added no chemicals (other than synthetic salt and frozen food for the fish) to the aquarium, and the coralline is almost out of control. It's a great problem to have. By the way, I have 6 24" fluorescent bulbs. Four were bought at home depot (cheap bulbs), while the other 2 are actinic. I also have a large population of feather dusters growing out of the rock and some have even built tubes of up to 2 inches and are living in the sand bed. Is this extraordinary luck, or did I accidentally hit on the aquarium conditions that the worms, coralline, and limpets thrive in (i.e., low light and not-so-low nitrate)? If my experience is unusual, I'll probably try to replicate the environment (minus the fish) in a 29 gallon, devote some study to all three, and write a paper detailing the conditions for anyone that might want to duplicate them (though their suitability would be limited to a fish only situation). Any guidance would be appreciated. Thank you in advance for your time. Sincerely, Richard Weatherly >> Wow, what an outstanding query, relating of experience and uplifting story... Congrats to you. And I think you may be on the verge of a great commercial success. I have only seen a few cases where the snails called limpets were so abundant as yours... and they are a blessing... And your lion and eel will not consume them (different diets all the way around), but I would do as you say, and save some of these "Chinese Hats" in another system... if for no other reason, for just safekeeping. And do "share the wealth" and supply some to fellow hobbyists... Your relating of the non-supplement use and results is exemplary by the several meanings of the term... Thank you for writing... please do consider tallying up your observations and sending them to one of the hobby magazines... Very useful. Bob Fenner

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