08 August 2005

A Sunday field trip along the C&O Canal

Australian malacologist Stephanie Clark, who was famous for more than 15 minutes back in May for rediscovering in Alabama a snail (Clappia cahabensis) that was presumed extinct (here and here), is working in D.C. this month. Yesterday, I took her out on a field trip along the C&O Canal and the Potomac River. We had an almost 5-mile hike on the canal’s towpath that included frequent stops to photograph the abundant butterflies and wading trips into the Potomac to search for snails. The butterfly above is a red admiral (Vanessa atalanta). There were many others, but I will save their pictures for another post.

Here is Stephanie standing in the Potomac while trying to teach me about freshwater snails. (Yes, we did get our pants wet.)

Stephanie’s favorite freshwater snail genus is Physa. The picture below shows two of them that Stephanie pulled out from the murky bottom of the river. If you look carefully, you will notice that the coiling direction of their shells is sinistral. In a previous post, I wrote about the coiling directions of snail shells and indicated that the shells of most snail species are dextral. But, in Physa, the normal coiling direction is sinistral.

Stephanie and I are planning another field trip for next weekend. Look for the results of that trip here next Monday.


h0g said...

Very much enjoying your blog Aydin. Say "G'day" to Stephanie for me from a fellow Australian :)

tony g said...

Pharyngula has posted a fine little piece on chirality this week . . .