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| Hello Ron, I thought I would start this thread rather than resurrect the many old ones I've had with you so hopefully things are more organized. I thought this thread could be a good illustration of how difficult it can be to identify snails through pictures and document my additional research efforts in narrowing down snails to a species ID. I have several snails breeding in my tank and would like to ID them to species if possible, mainly as an academic exercise. Please add in your comments and correct me where I make mistakes. Up first, snail #1, probably from the genus Trochus Top Down shot of baby: 
Shot of baby with other snails, showing the shell from an angle: 
Closeup of underside with operculum in sharp focus: 
Picture of adult snail showing a very distinct yellow/white line on the head: 
Purchased from FragsNCrabs(local vendor), who got them from reefsavers(local coral "research" facility). I contacted reefsavers and they said they are an indopacific snail with an ID of Trochus histrio Trochus histrio From gastropods.com: http://www.gastropods.com/6/Shell_2426.html It looks like the last picture of the shells could be a possible match, but there are two things that make me question that: 1. The color pattern on the shell looks different, especially the lack of green seen in the baby shells. But I know this isn't a very good ID characteristic 2. The operculum shown with the first picture on gastropods.com is very different looking from the operculum in my baby snails. While I do not have a picture of an operculum from one of my adult snails yet (will try again soon), it has the same pattern as the baby snail pictured above. So I browsed through many other Trochus species on gastropods.com and found more that look very similar with a closer matching color pattern (but no operculum pictures): Trochus radiatus http://www.gastropods.com/9/Shell_2259.html and Trochus stellatus http://www.gastropods.com/3/Shell_1683.html Next post will see if google searches help any: Brian
7 years FW, 5 years SW
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Well, I just lost my post accidentally on my google searches that had several interesting links, but I don't want to take the time to find them again. Basically the google searches yielded more shell pictures, but nothing definitive on ID. I did find this last link on Trochus histrio that describes telling juvenile T. histrio from another closely related snail and describes 6-7 ridges on the bottom of the shell, which my juvenile snails do have. http://www.spc.int/coastfish/News/Trochus/Trochus7/Trochus7-05-histrio.htm But nothing found through google was definitive, so the next step is consulting the various books on seashells. The Compendium of Seashells, Shells of Taiwan Illustrated in Colour and The Book of Indian Shells all looked like my best options, but none are available in my library. Dr Shimek do you have any of these? If so, could you look up these three species and see if any match my 3 species? I found the book Shells of the Western Pacific in Color v2 by Tetsuaki Kira in my library and it has pictures of Trochus stellatus. There are a few descriptions I found in the description that don’t eliminate Trochus stellatus: “The basal surface also bears 7-8 granulated spiral ridges” – I count 7 in my picture in my first post. There are two sentences I don’t really understand though. Could you explain these a little: “In the umbilical hollow, the columella is screwed inward. The columellar and basal lips are denticulated” Denticulated means toothed, but the rest of the words have a series of definitions in google. Next post will detail my literature search on these three species. Brian
7 years FW, 5 years SW
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| Dr Shimek, Do you have any recommended databases I could search to try to identify an expert that is researching any of these species? I've tried the databases here at UH and I have found no useful articles on any of these species. Or any journal titles that deal with snail identification or similar topics that I could try to find online or borrow through our library? Google scholar has been slightly better, but nothing especially helpful. Brian
7 years FW, 5 years SW
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Hi Brian,
I have the Compendium, and it has illustrations of histrio and radiatus. It is impossible to distinguish these species by the images shown.
You asked, [b]" Could you explain these a little:
'In the umbilical hollow, the columella is screwed inward. The columellar and basal lips are denticulated'"[/b]
The first sentence means: In the hollow opening on the bottom of the shell, the inner edge of the aperature appears to be folded as if it were "twisted."
The second sentence means: The bottom and columellar (inner) edges of the lip (most recent part of the aperture) have a series of "bumps," "nodules," or "teeth" on them.
Such denticles generally show up only on mature animals. I don't think yours will have them.
I think you have reached the point where it is essentially impossible to identify the shells from illustrations in books. This happens a lot. Contrary to what most hobbyists seem to think, it is impossible to identify most of their corals from illustrations. It is difficult or impossible to do this with many other taxa as well.
If these were my animals and I was serious about identifying them, I would get copies of the original species descriptions of the candidate species and see if the shells matched either of the original descriptions unambiguously. I suspect, however, even after you do this step - and it is a necessary step - you will find that the animals still will not be clearly and definitely placeable into one or the other species.
At this point, to get a definitive identification, you will need to sacrifice a few shells and send them to a taxonomist who works on these animals and who has access to a large museum that has specimens that yours can be compared to. You will need see if that taxonomist will do you the favor of comparing your specimens with the specimens in the museum and deciding to which species they belong.
There are two problems with this approach. First, I don't know many taxonomists working with the group (probably the best option is Jim McLean, an emeritus curator at the Natural History Museum of Los Angeles County). Second, once you send the specimens off to the taxonomist, you are the mercy of his/her schedule; it can - quite literally - take years to get a reply.
The other option is to contact a curator of a large museum that has specimens of the potential target species, and arrange to visit the facility to do the comparisons yourself. This is rather routinely done, and most museums will allow you access to their collections as long as it is not for a frivolous exercise.
Cheers, Ron
"The difference in mind between man and the higher animals, great as it is, certainly is one of degree and not of kind. The love for all living creatures is the most noble attribute of man." Charles Darwin (1809-1882)
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| Hey Brian, THe Houston Museum of Natural Science actually has a very reputable malacology collection, and there is also an active conchology society locally. You might be able to get contacts through there. I believe the new curator at the museum is Wes Tunnell; previously it was John Wise but he has moved on it seems.
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| Susan, Thanks for the info, I sent an email to Houston's museum, but I will send another one requesting that the email get forwarded to Wes Tunnell as well. I have already received a response from Jay Cordeiro about who he might consider someone working on Trochus with a couple of names and a BUNCH of additional references that might help me out. I will be getting some books through ILL this weekend to get the original description for each species. I also found some information on each species here: Trochus stellatus Gmelin, 1791 http://data.acnatsci.org/obis/search.php/6702 Trochus radiatus Gmelin, 1791 http://data.acnatsci.org/obis/search.php/43801 Trochus histrio, Reeve, 1848 http://data.acnatsci.org/obis/search.php/6695 Dr Shimek, I also found a shell in my aquarium from one of the old adults that must have expired. It has prominant denticles, I took a picture but left my USB stick at home. I will post it tomorrow. Once I have the original descriptions I can see if this feature eliminates any of the options. Another question for you. When distributers use the term "Indo Pacific", what does that mean? Would that include Australia? In this case it won't eliminate any possibilities, I would guess it is another of those useless terms like "SPS" in most cases, just in this situation refers to a useless location name. Brian
7 years FW, 5 years SW
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Hi Brian,
The term Indo-Pacific isn't quite useless, but it is close to being so. It does offer some discrimination from organisms found in the Atlantic.
Indo-Pacific really can be interpreted to include anything in either the Indian or Pacific Oceans. Generally, there is a tendency for it to be restricted to the tropical regions of that great water mass, but as for providing a specific locality for identification it is almost useless.
Cheers, Ron
"The difference in mind between man and the higher animals, great as it is, certainly is one of degree and not of kind. The love for all living creatures is the most noble attribute of man." Charles Darwin (1809-1882)
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| Ron, I finally remembered my USB stick, here are the pictures I took of two large snails that have passed on: Please correct me if I'm wrong, but these look like the beginning of denticles. I do have one snail that is twice as large as these shells, still alive, and I pulled him out and the denticles are much more pronounced (at least twice as big). But when I pulled him out my camera wasn't available and he hides well in the rock, I haven't seen him since to get a picture. 
Here is a smaller shell next to the larger one, you can see the denticles are much smaller than the shell on the right. 
My second question for you: Do these pictures show the umbilical hollow well enough to verify this statement: "In the umbilical hollow, the columella is screwed inward" I'm still not very clear on what a columella is. Brian
7 years FW, 5 years SW
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Hi Brian,
Yes, they do look like denticles, and yes, the umbilical hollow is well enough developed to verify that the columella looks "screwed inward."
The columella... The usual manifestation of this structure - and the one that is generally visible - is the inner edge of the aperture. But, now visualize the snail with all of the outer whorl edges gone. The center of the snail's shell would be a "screw" like structure - a column - of calcareous material that is found in the center of the animal. That central column is is the "columellla."
Hope that helps.
Cheers, Ron
"The difference in mind between man and the higher animals, great as it is, certainly is one of degree and not of kind. The love for all living creatures is the most noble attribute of man." Charles Darwin (1809-1882)
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| Ron, Yes I'm more clear on the columella now, thanks. I actually just heard back from the Natural history museum in Houston and they are very happy to help me narrow down an ID. I will be meeting with them in early June and I'll report back. Brian
7 years FW, 5 years SW
Education is the solution to pollution, not dilution.
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