Tallus Snail
Sonorella spp.
This snail was spotted by Cass Blodgett near the summit of one of the low basaltic hills that make up the Deem Hills, Phoenix, Arizona, USA. 27 Feb. 2010.
Among the tumble of rocks about the tops of many Sonoran Desert hills and peaks is a surprising survivor, the Tallus Snail. Many similar species have been described, each a population isolated by the intervening low deserts. What is surprising is how these mollusks can aestivate (like hibernation) for many months while the desert is in the grips extended drought and searing temperatures above 40°C. When rains return the snails' opercula open (an operculum is a doorlike cover that seals the snail inside its shell), and only then can they feed, mate, and reproduce.