The League of Extraordinary Molluscs

Posted by Graeme Lyons , Saturday 25 February 2012 07:39

I had a great day out in the field yesterday looking at molluscs with Martin Willing. Overall, an 8/10 day I'd say! Martin showed me how to survey for aquatic molluscs in ditches on the Pevensey Levels. All day I was drip fed advice on habitat management and autecology of the different species and while Martin was surveying, I was learning the snails and keying them out myself. The one downer was that I didn't see the rarest one, Little Whirlpool Ramshorn Anisus vorticulus but why don't I start with what I did see? The above photo is perhaps my favourite snail of the day, Shining Ramshorn Segmentina nitida.This rare little beast (along with vorticulus and two more species I will mention below) form a 'guild' of scarce species that often occur together. I like guilds, they help me make sense of the otherwise chaotic world of natural history.

Here is Martin surveying with the longest net I have ever seen that can get right across to the other side (and the bottom) of the ditches! Inevitably I also got smacked in the face a few times with the handle!
This next one is a bit of a 'tart's tick' in the mollusc world, actually. It's the Margined Ramshorn Planorbis planorbis. Quite widespread and common but a new one for me.
Another common snail that I saw for the first time was the Flat Valve Snail Valvata cristata, again a widespread species but also in the guild of rare species is it's much rarer cousin, Large-mouthed Valve Snail Valvata macrostoma. This was a small individual and the light was going but you get the idea...
I also keyed out this species new for me, again not scarce but a smart snail all the same, the Twisted Rasmhorn Bathyomphalus contortus. Very tightly coiled with a deep wide umbilicus.
Martin also showed me the fourth member of this guild but I didn't get a photo this time. The rare pea muscle known as Pisidium pseudosphaerium. But the fun didn't stop there, oh no! I also saw some old friends I have not seen for many years including the Nine-spined Stickleback, something I have not seen since the electro-fishing days.
And Martin also pulled out a Great Silver Water Beetle, an impressive beast. Something that I used to catch regularly at light traps at Dungeness.
Other highlights included a Short-eared Owl as we were leaving. Plenty of Saucer Bugs and a single specimen of the tiny Plea leachi. I also photographed this bizarre looking flatworm but try as I might I can't find the key. I'll have a more thorough search on my return from the staphylinid workshop today at Dinton Pastures. Right, I better get ready! Oh, I ended the day on 3785 species.

6 Response to "The League of Extraordinary Molluscs"

Neil Says:

Looks like an excellent days ditch dipping. I am currently try to ID the many small dytiscids I find in ditches here in Essex. Its not easy!

Gibster Says:

Your 9-spined Stickleback seems to be

Freshwater molluscs undoubtedly rock, I have the key...just point me at the nearest pond!

Good luck with the Staphs!

Graeme Lyons Says:

Good luck with your ditches Neil. Seth, I can help you with natural history but counting to ten, you're on yer own!

Gibster Says:

Counting to ten I can manage, thanks. Just count all of your fingers and add one. Easy.

Mark G. Telfer Says:

Graeme, I've spent time in the field with Martin too and it was a fantastic learning experience. Could the flatworm be Dendrocoelum lacteum? Mark

Graeme Lyons Says:

It sure was Mark. As for the flatworm, I only pohotographed it after realising that there were very few species and I may be able to do some of them from a photograph. Can I find the rather tiny book since I have moved house? I bet it is wedged inside another book somewhere!

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