dejayM's picture

Common Whelk

Observed: 30th October 2013 By: dejayM
Biological Recording In ScotlandHighland Biological Recording GroupOrkney Biodiversity Records Centre
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whole
size
under
choc & cream
edible - yum!
compare
Description:

Sometimes very large, up to 4½ inches (110mm). Animal is not often seen (to be photographed), nor is it described in the masterbook by Hayward & Ryland (Handbook of Marine Fauna) but is very distinctive cream colour with chocolate marbling - pictures 4&5.
Picture 3 (underwater) shows the supersized siphon.
Picture 6 shows a Dog Whelk for comparison
WoRMS

Identifications
Species interactions

No interactions present.

Species with which Common whelk (Buccinum undatum) interacts

Comments

dejayM's picture

glory

There are not very many posts showing the Common Whelk in all its glory and there is plenty of confusion about whelks in general.
There is 'help' in all the books but some references overlap the Common- and Dog-whelk descriptions. Both, for instance, are described in the Collins Complete (Guide to British Coastal Wildlife) as having a conical spire with ridged whorls and reasonable descriptions are absent from the RSPB Handbook of the Seashore.

That there is some confusion is illustrated in http://www.ispotnature.org/node/120786 where even experts have disagreed (though some have recently shifted their agreements)
A glance along Other Observations, above, shows that is is easier to tell their eggs apart than their shells.
What we should be looking for, apart from size difference in adults (Common Whelk is by far the larger), are the sculpted longitudinal ridges shown in Picture 2 (though note in P4 how smooth the shell is). There is often little difference in shape, opening, siphon or colour but another clue, if you have both to hand is the relative narrowness of the apperture of the Dog Whelk.
The animal, should you see it, is completely different though - once you've seen a mobile Common Whelk, you will know what you've found!
There is a good summary here http://molluscs.at/gastropoda/index.html?/gastropoda/sea/common_whelk.html
but I was taken aback by the statement "The whelk mainly lives in cold water with a salt content of around 2 to 3 percent. The whelk lives on different soils, but it is most frequently found on soft ground, for example muddy and sandy...."
Later..
Thanks for your response below Cathal - I am so eager to set examples but might get lost in the detail!

nightfly's picture

Very good pictures Derek,

Very good pictures Derek, especially pic 6 which gives a comparison of both in one shot. I think this simple approach is often overlooked as a tool for describing differences in similar species. Sometimes it can do a much better job than many words can do. Good post.

Cathal.

JoC's picture

taken aback

is it the word 'soil' that took you aback? It could be a translation for substrate (the post is from Austria). Or is it something else I have missed? In any case good pictures which unusually show the body of the mollusc.
Jo

Jo

dejayM's picture

salt

Yes, there are a few very forgivable translational 'errors'. But the statement about 2% salt (normally nearly 3.5%) is also interesting. Is this creature to be found high in estuaries?

JoC's picture

Sea saltiness

Yes, 3.5% would be a better figure... Austria has no sea shore...
I don't think it's an estuarine species either,
Jo

Jo

dejayM's picture

Coming back

See how valuable a comment trail is? (usually!)
I returned because I am about to post another. Maybe we should not repeat posts but my new one will be different, so I look forward to a decent comment trail!. http://www.ispotnature.org/node/698508