Pea Mussel - likely species?

[Yashca]

I caught a pea mussel earlier this year at Forge Valley, North Yorkshire. I caught it accidentally whilst sweeping my net through some mud in one of the wider areas of the river.

I didn't get a picture of it, unfortunately, because I had no camera at the time, and promptly released it.

Earlier today I decided to make a list of all the non-marine molluscs I have ever seen, and my thoughts were drawn to this pea mussel. I have no idea how many species occur in the UK, and so will probably just have to put it as a genus record, but I am not sure if more than one genus occurs in the UK.

Is their another genus other than Pisidium?

And if I was to return to the same site and catch another (sweeping net through the mud should do it, shouldn't it?) how would i go about getting it to species level?

Thank you, Yashca.

[The Woodman]

There's the Sphaeriidae -Orb Mussels or Pea Cockles and Dreissenidae - the Zebra Mussel and the big bivalves of course.

I've suggested an alternative guide in your other post but also there is the Collins Field Guide to Freshwater Life by Fitter and Manuel and an area guide I use as my bible here ..A Natural History of the Lakes, Tarns and Streams of the English Lake District by Geoffrey Fryer. A gem of a hand written and illlustrated book. ISBN 0-900386-50-9

[Naiad]

There are two genera, Pisidium and Sphaerium. Sphaerium have two siphons and Pisidium have one. Across the two genera there are about 20 UK species. Apparently the shell hinge is important for species identification, but I haven't done this myself.

[diggleken]

just to add some very simplistic info which may help in general terms, I find Duck mussels are usually in sandy bottomed water and the bigger Swan mussels are more muddy loving.
Peas I dont know though...............!
Cheers
Ken

[Yashca]

I've seen swan mussels, but never duck mussels. Can they be found anywhere in Yorkshire?


Naiad: When you say the shell hinge is important, do you mean an inside view of the hinge in an empty shell? Or an outside view of a living shell?

[Naiad]

I'm not entirely sure - it's just what the books say - but I think it means empty shells, and you need some magnification as well.