Wednesday, December 21, 2011

Desert Snails

These spiral beauties are the shells of talussnails (Sonorella spp.), a type of land snail that survives in between rocks in Arizona deserts and canyons, grazing on mosses, lichens, and leaf litter. I haven't figured out which species. If you want to be a land snail biologist, and want to identify the species, you need to get a good look at their penises. Unfortunately, I haven't come across a live one yet, in order to determine the shape and size of their gonads. This, plus the details of shell morphology, are the most important characters used to distinguish between them. All snails have a penis, since they are hermaphroditic, which is very handy for reproduction, since both individuals can become pregnant when they copulate. At least if I do find a live one, the sex won't matter!

Although there are over 200 species of snails native to Arizona, we know very little about most of them. Many are considered very rare, with populations limited to isolated mountain ranges. Threats from mining and recreation have raised enough concern from biologists to petition for protection under the Endangered Species Act, as with the Rosemont Talussnail and Sonoran Talussnail. Others, are considered pests, such as the New Zealand Land Snail, which has inspired annual conferences to discuss how to eliminate them.  

Most snail reports are heavy with measurements and description, but I did find a few lines referring to snail intelligence and behavior buried inside a 69 page report, where two biologists came eyestalks to eyes with a snail:

"With its eyestalks still turned towards us, the snail appeared to increase its traveling speed across the boulder and attempted to go down the side of the boulder and out of our sight. We considered this to be evasive behavior."  Schmalzel and Archer, 2010

They didn't say if that one escaped, or if it became one of the many sacrificed for taxonomic analysis. I hope it got away!

1 comment:

Tom said...

Evasive for a reason, it probably knew those biologists wanted to look under its shell.