The Life Aquatic

Posted by Graeme Lyons , Saturday 9 October 2010 21:47

I am writing this from Flatford Mill Field Centre where I am spending the weekend on an aquatic snails identification course. I have (so far) found, keyed-out and identified about 10 aquatic molluscs. I even got a video of a translucent Keeled Ramshorn's Planorbis carinatus heart beating, although I have not been able to upload it onto my laptop yet. Anyway, here are a few of the species I have looked at so far:
This is the Whirlpool Ramshorn Anisus vortex, it's quite common but has a much rarer cousin that is found in some sites in Sussex.
This tiny translucent species is the Lake Limpet Acroloxus lacustris, note how the spur does not project parallel to the long axis of the animal and goes off to one side.
This one was my favourite, a really pretty little snail called the River Nerite Theodoxus fluviatilis that looks like the Slipper Limpets you get on Brighton beach, only much smaller and it's also (probably) native. It even has the little ledge underneath that the Slipper Limpet has.
Finally, this snail has an operculum (a door that locks it in) that sticks to its body when the snail is out of its shell. It's called the Common Bithynia Bithynia tentaculata. Operculums can have spiral patterns or concentric rings. This one has concentric rings.
Also, I've had a fish tick! We have caught at least four Spined Loach Cobitis taenia. I used to catch Stone Loach Barbatula barbatula by hand in the brook by my house when I was a kid and I thought these looked very different straight away. They are quite compressed laterally with a bullish face, square-ended tail and more obvious spotting along the body. They also have spines under the eye which are very hard to see, until you get one stuck in your hand that is. Spined Loach appears to be much more restricted in its distribution than Stone Loach too.

Whilst I'm on the subject of fish, we pulled this little Elver (instantly christened Elvis) out of an old muddy ditch whilst looking for snails. It's been a long time since I saw an Eel, I really miss the electrofishing that Matt Self and I used to do at the RSPB. Freezing cold, covered in Eel slime, exhausted  from carrying boats and generators but we got to see some of the best reserves from places few people ever get to see. Eels are probably one of my favourite species in the UK for that reason alone. I can smell the Eel slime just thinking about them. Mmm!
Whilst we were having lunch, I spotted a squash bug on a barn and thought it looked a little more slender. than the common species. I was sure it was not Dock Bug Coreus marginatus and soon figured out it was Box Bug Gonocerus acuteangulatus. It appears that this once very restricted (RDB1) species has recently undergone a rapid expansion after changing its habits and not being so picky about its food. All the same, it's great to see one and another new species for my list.

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