The U.S. Fish and Wildlife Service recently declared the Ozark pyrg, a small snail native to Arkansas and Missouri, as "presumed extinct."

No Ozark pyrgs have been confirmed in surveys since their first discovery in 1915. As a result of what the Fish and Wildlife Service called "rigorous, science-based surveys," the pyrg will not be listed under the Endangered Species Act (ESA).

The spiral-shaped Ozark pyrg was originally found more than 100 years ago in the White River near Cotter and in the North Fork White River near Norfork, extending into Missouri.

The Norfork Dam and Beaver Fork Dam, both constructed in the 1940s, were built just upstream of the original collection points. The damming of the White and Norfork rivers drastically changed the habitat of the area. The snail likely required shallow, flowing water and clean gravel to survive and reproduce, and this habitat was destroyed or reduced above and below the dams, the wildlife service states.

In 2010, the service was petitioned to list 404 species from the southeastern United States, including the Ozark pyrg. In 2011, the service published a 90-day finding that the Ozark pyrg may warrant listing based on information in the petition. The recent determination ends the agency’s review of the snail’s status under the ESA.