Some snails on campus

I'm always telling students of the ponds 'don't fall in' so it was disappointing that I got an entire shoeful of water this lunchtime. All in the name of furthering my snail-related knowledge. I found this specimen amongst the brooklime (memorably named Veronica beccabunga) creeping around the edge of the pond. It's come out quite easily with Daw and Ivison's Bristol key.

So it seems convincingly to be Succinea putris,  the Amber Snail. My Victorian snail-fancier Mr Adams says they "inhabit moist places by water. Though amphibious it is seldom seen in the water except in spring when on its way from its winter quarters in the mud."

CC image by James K Lindsay

Naturally things are never entirely simple and Cameron's land snails book describes other Succineids that look extremely similar when the snail's not in residence. But I think we can discount them (one is rarely over 12mm and is commoner in the north, and the other is restricted to East Anglia). A hundred years ago I think taxonomists were making it yet more complicated, as Mr Adams says "the varieties seem to graduate into each other, and into the type in a most perplexing manner, and I advise the tyro [beginner] to leave them severely alone."  Severely alone. 

Succinea putris means 'amber' and 'stinking'. Amber is the colour of the shell and I'd like to think 'stinking' refers to where it lives rather than how it smells itself.  Here's the snail I got the wet stinking sock for:

CC image by BJShoenmakers

So this one (since it's freshwater it needs a different key.. I used Collins) is a Great Ramshorn Snail, Planorbarius corneus (I wrote vorneus above as there's a misprint in Collins, helpfully). It's massive and looks like a ram's horn so I guess it's well named. 'Planorb..' means flat coiled, and 'corneus' means horn-like. These Latin names aren't just random you see.

Planorbids have various methods of obtaining oxygen while they're underwater. They have a lunglike cavity which they can fill with air (they are pulmonate snails like those on land, but they've returned to an aquatic habitat). They also use part of their mantle as a gill by extending it into the water. And they've independently evolved haemoglobin so they can keep hold of their oxygen effectively (their bodies do look noticeably red). The sediments they crawl across at the bottom of ponds can be pretty anoxic places so all these methods are useful.