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Gibbula umbilicalis
(da Costa, 1778)
Rob Durrant Re G. umbilicalis, these three were all from the same location, very close by. Apologies for blurry pictures, but these were taken incidentally whilst focused on other specimens.Ian Smith Agree. The low number of wide (relative to small shell) bands, colours and sculpture are all spot on. Rob I think you should be congratulated, as someone who seems to have worked alone for some time, for spotting the difference in the Phorcus you found in company with Gibbula umbilicalis. I'm not too surprised as I've seen your records on irecord, and they have been a cut above the rest. I hope you'll stay with us and maybe even consider joining the Conch. Soc. eventually. My only request is that you are not coy about localities (e.g. N. Devon will do) as they are an important aid, and it is difficult enough to identify from photographs, as you have seen.
Rob Durrant Thank you so much for your generous and very encouraging comments, Ian. Yes, I would certainly consider joining the Conch. Soc. eventually, though at the moment I'm very much a generalist. I take your point about localities. It's just that many of the species I have found have few or no records from the Bristol Channel, or even further afield, and I wanted to keep the options open for 'new' species to turn up in unexpected areas. I have indeed seen how difficult the ID process can be, quite an education! :D
Jan Light Just to say I endorse Ian's comments. Queries such as yours on top shells sure keep those with more experience on their toes!
Message posted on British Marine Mollusca on 24 Oct 2013
Rob Durrant These found under a stone on an exposed beach in a small mid-shore pool, where were abundant Littorina saxatilis and Gibbula umbilicalis. Shares qualities of both, and presumably Gibbula of some sort. What, please?Simon Taylor I'd say these are young Gibbula umbilicalis
Dave Rolfe I would agree. Assuming it is mainland Britain, if it were the channel Islands I may say G.pennanti.
Rob Durrant Thanks, Simon. To me, the raised lines on the shell surface and the patterning being speckled more than lines differentiated these from all the other G. umbilicalis around, but it was mainland, Dave.
Ian Smith If you look at the G. umbilicalis account at http://www.flickr.com/photos/56388191@N08/9871482474/in/set-72157635756387204 and scroll down to "similar species" and click on the links, you will see why these are young Phorcus lineatus.
Jan Light I agree with Ian's ident. The genus name that might be more familiar to some is Osilinus or even Monodonta.
Rob Durrant Certainly the Monodonta tooth is very clear on one of the images, which I did notice; but am not sufficiently knowledgeable about whether other species might share that characteristic.
Rob Durrant I will reread your very thorough study on Flickr, Ian Smith, just had a glance at the relevant section. Again, thanks for that resource. Eventually I will learn! But I am somewhat encouraged when it isn't always obvious even to those far more expert than me :D
Ian Smith Identifying 3D curved objects from 2D images is much more difficult than with object in hand. "he who never made a mistake never made a discovery" (Samuel Smiles).
Julia Nunn I think they are Littorina saxatilis and Gibbula umbilicalis. They don't look like any juvenile Phorcus/Osilinus/Monodonta I have ever seen.
Julia Nunn I agree that one of the pics looks very like G. pennant - I was about to ask the same question about the area they were found
Simon Taylor I am happy to concur that these are juvenile Phorcus. I wasn't 100% happy with the ribs. Presumably there were adults at the site too.
Rob Durrant I can't say I was aware of any, Simon. Not to say there weren't; but I was very conscious of large numbers of G. umbilicalis. It was a beach of strata running perpendicular to the prevailing waves and even barnacle cover was not great; so I was concentrating on the few crevices and undersides of the few stones that I could manage to lift. Pretty low down the shore, at least lowest part of mid-shore. Don't you think that the tooth is the most telling feature, given that juveniles of both species, as Ian's extensive collection of images shows, can present very similar appearances?
Dave Rolfe I have to confess I did not notice the tooth, but having done so and also having read others views I also have to agree that it does look like juvenile P. lineatus.
Message posted on British Marine Mollusca on 23 Oct 2013
Ian Smith “For brilliancy of colouring and diversity of painting, we have nothing comparable among our native shells, to this beautiful little Phasianella [=Tricolia pullus].†(Forbes & Hanley, 1849.)
Soft parts are pretty smart too. Set of images with pop-up interpretive notes on Flickr, with full image-linked account under image 2 at http://www.flickr.com/photos/56388191@N08/collections/72157633613018744/Sheilah Openshaw http://www.google.co.uk/imgres?imgurl=http://www.marlin.ac.uk/imgs/o_calziz.jpg&imgrefurl=http://www.marlin.ac.uk/lzspeciesreview.php?speciesid%3D2849&h=600&w=800&sz=16&tbnid=62-2PTDSQPgseM:&tbnh=95&tbnw=126&prev=/search%3Fq%3Dtopshell%26tbm%3Disch%26tbo%3Du&zoom=1&q=topshell&usg=__pv2oDXBfo7SkY89Eypr4CcoppMg=&docid=06wScToUdTCP-M&sa=X&ei=eCUCUvCRLYH50gXW5YCwCA&ved=0CC8Q9QEwAA&dur=0 Topshell
Paula Lightfoot I love these! I collected loads of the shells on Herm but have never seen a live one, those photos are amazing!
Ian Smith Thanks Paula. I've never found a 7mm adult alive. As with sea slugs, the smallest juveniles are hundreds or thousands of times more numerous than full grown ones - to maintain stable populations, on average all but one or two of the hundreds / thousands born from spawning of an individual need to come to a sticky end before they can in turn breed successfully. I often find 5- 10 juveniles by collecting a marge tub of filamentous red algae from shallows or deep pool at LWS and searching it small bit at a time under low power stereo microscope. But you need to be on S or W coast Britain round to Orkney. Maybe divers could try the technique?
Paula Lightfoot I'm sure we could! No point looking here in Yorkshire I guess (although the NBN Gateway shows 2 east coast records...?) but I will look for them in Strangford Lough!
Simon Taylor These and your other pictures on flickr are really superlative images Ian, truly fantastic. Please please post a link to them in the British Marine Mollusca group, or may I?
Simon Taylor Paula, are you at Strangford Lough later this month? If so, I'll see you there. Incidentally, did you which datasets contain those spurious Tricolia records from Yorkshire? Not the Conch Soc I hope. If it was, I will endeavour to re-check them and have them removed if required. I'm very keen to improve the veracity of the Conch Soc marine dataset.
Paula Lightfoot Yes can't wait! With David Kipling, Sarah Bowen and Mandy Knott, we will see you there :) One record is in the Conch Soc dataset, the other is not (and its not in the Seasearch dataset either before anyone asks)
Simon Taylor Ok, as soon as I can get Recorder 6 and Windows 8 to work happily together I will get stuck into investigating these odd records. I'm very keen, and I know Ian Smith shares my feeling on this, to ensure the Conch Soc dataset is as reliable as possible. Really looking forward to meeting some people at Strangford who I've only ever met 'virtually' before.
Ian Smith As there is a Dutch name for Tricolia pullus, I wonder if any Dutch members can tell us if there are North Sea records/images from the Netherlands? If so, it would lend credence to those on NBN. Simon Taylor, you're welcome to put a link on BMM, but please add a note of apology for double posting as most members are also in this group.
Paula Lightfoot There are 9 Dutch records on GBIF but only 3 are georeferenced (one is a fossil!) and they are from south Holland right on the border with Belgium - so not much further north than the UK records from Kent.
Paula Lightfoot On a similar subject, records of Gibbula umbilicalis and Osilinus lineatus for the east coast of Scotland have been removed from the Seasearch and Porcupine datasets so will disappear from the NBN Gateway next time those datasets are uploaded :)
Marco Faasse Ian Smith and Paula Lightfoot, the marine fauna of The Netherlands is extremely poor in species (let's say like Kent, but even worse). Most of the coast is sand; rocks are absent, the only hard substratums being coastal defense works. The result is that beachcombing is much more popular than rockpooling etc. Many records of rare species pertain to specimens washed ashore on floating objects coming (mostly) from the south. I understand that people are happy to record species, but recording beached specimens has led to much confusion due to people from other countries assuming these records pertain to specimens living on our coast. Tricolia pullus is an example of a species that has only been recorded washed ashore or fossil in The Netherlands. The different character of our shore also means that the absence of Tricolia here doesn't preclude its presence in Yorkshire ...
Simon Taylor Very interesting comment Marco. I think there is room for beach recording so long as the nature of the record is made very clear. Personally I tend to only record obviously fresh-dead beached shells, particularly as in some areas in East Anglia (and presumably in parts of mainland Europe) there are coastal exposures of very fossiliferous strata, e.g. the Red Crag, containing specimens of extant species which could easily be confused with modern shells.
Marco Faasse I agree with you, Simon Taylor, the problem is not with the recording of beach finds, which may be interesting indeed, but in recording the nature of the record (which is missing even in some publications in scientific journals!). Citations and compilations should be very careful to avoid misunderstandings.
Paula Lightfoot I recorded Tricolia pullus on several dives in Strangford last week, both by collecting red seaweeds during the dive as Ian suggested, and I also spotted and photographed some underwater. So yes, divers can easily record live specimens of this beautiful species if they're in the right area and habitat.
Ian Smith Congrats. Nice picture of an adult, Paula . I wish I could find one, as well as juveniles, on the shore. Last week I collected red weed at exactly the same spot as I got juveniles 4 weeks earlier. This time not one! As compensation I got all four spp. of British Lacuna, though all juvenile at this time of year. I saw not a single sea slug while on the shore, but microscope examination of weed and some stones produced 9 spp. including a brilliant Hermaea bifida (8mm - largest slug found) on Griffithsia, and Placida domingo (dendritica) on the single small strand collected of Bryopsis plumosa.
Message posted on Seasearch Identifications on 07 Aug 2013
Rob Durrant These found under a stone on an exposed beach in a small mid-shore pool, where were abundant Littorina saxatilis and Gibbula umbilicalis. Shares qualities of both, and presumably Gibbula of some sort. What, please?Simon Taylor I'd say these are young Gibbula umbilicalis
Dave Rolfe I would agree. Assuming it is mainland Britain, if it were the channel Islands I may say G.pennanti.
Rob Durrant Thanks, Simon. To me, the raised lines on the shell surface and the patterning being speckled more than lines differentiated these from all the other G. umbilicalis around, but it was mainland, Dave.
Ian Smith If you look at the G. umbilicalis account at http://www.flickr.com/photos/56388191@N08/9871482474/in/set-72157635756387204 and scroll down to "similar species" and click on the links, you will see why these are young Phorcus lineatus.
Jan Light I agree with Ian's ident. The genus name that might be more familiar to some is Osilinus or even Monodonta.
Rob Durrant Certainly the Monodonta tooth is very clear on one of the images, which I did notice; but am not sufficiently knowledgeable about whether other species might share that characteristic.
Rob Durrant I will reread your very thorough study on Flickr, Ian Smith, just had a glance at the relevant section. Again, thanks for that resource. Eventually I will learn! But I am somewhat encouraged when it isn't always obvious even to those far more expert than me :D
Ian Smith Identifying 3D curved objects from 2D images is much more difficult than with object in hand. "he who never made a mistake never made a discovery" (Samuel Smiles).
Julia Nunn I think they are Littorina saxatilis and Gibbula umbilicalis. They don't look like any juvenile Phorcus/Osilinus/Monodonta I have ever seen.
Julia Nunn I agree that one of the pics looks very like G. pennant - I was about to ask the same question about the area they were found
Simon Taylor I am happy to concur that these are juvenile Phorcus. I wasn't 100% happy with the ribs. Presumably there were adults at the site too.
Rob Durrant I can't say I was aware of any, Simon. Not to say there weren't; but I was very conscious of large numbers of G. umbilicalis. It was a beach of strata running perpendicular to the prevailing waves and even barnacle cover was not great; so I was concentrating on the few crevices and undersides of the few stones that I could manage to lift. Pretty low down the shore, at least lowest part of mid-shore. Don't you think that the tooth is the most telling feature, given that juveniles of both species, as Ian's extensive collection of images shows, can present very similar appearances?
Dave Rolfe I have to confess I did not notice the tooth, but having done so and also having read others views I also have to agree that it does look like juvenile P. lineatus.
Message posted on British Marine Mollusca on 23 Oct 2013