Pennsylvania Land Snails
Photo(s): Ed Thompson
Hendersonia occulta (Say, 1831)
Common name: Cherrystone drop
The cherrystone drop is an exciting land snail to see in Pennsylvania because it is uncommon and has unusual features. Its shell is very like a cherry pit in size and shape (approximately 6 to 8mm in diameter), but having an aperture for the snail’s soft body to emerge, of course. The shell can be a variety of subtle colors, including a cinnamon red, or pale yellow, green or blue, while older shells are bleached white.
The animal is quite different from other Keystone State land snails in its anatomy and taxonomy. The cherrystone drop is a Neritopsine, so individuals can be male or female, rather than hermaphroditic like the rest of Pennsylvania’s land snails. It has an operculum, a tiny cover to close the aperture when retracted, and eyes at the base of its tentacles instead of at the tips. Most of its relatives are tropical.
The cherrystone drop is a calciphile, found only on calcium-rich soils of steep limestone glades or hardwood forests in the Appalachian Mountains, though found on flatter grasslands in the Midwest where it also occurs. It can be very patchy in its distribution, with large expenses of apparently suitable, yet unoccupied, habitat. Colonies may be dense, with dozens of individuals per square meter.
Pleistocene deposits show that this snail was once much more common in North America, but is now know from only sporadic locales in a dozen states (e.g. Hubricht, 1985). In Pennsylvania, H. occulta is found at only a few sites in the southwestern quarter of the state. It was first found in Pennsylvania in 1831 or ‘32 by James S. Craft a Chartiers Township landowner (MacMillan, 1950).
Ken Hotopp, 1/2/06
Development of this site was supported by the generous contributions of Pennsylvanians to the Wild Resource Conservation Fund.