Endangered Species in the Pacific Islands
Newcomb's Snail / Erinna newcombi / Pupu wai lani
Newcomb’s snail is unique among the Hawaiian snails in that the shell spire, typically associated with snails, has been substantially reduced. The result is a smooth, black shell formed by a single, oval whorl, 6 mm (0.25 in) long and 3 mm (0.12 in) wide.
Habitat & Behavior:
Newcomb's snail is an aquatic snail and is known to occur in streams and springs located in the mountainous interior on Kaua‘i. Populations of the snail are found at an average elevation of 306 meters (1,005 feet), and range between 196 meters and 396 meters (643 feet to 1,299 feet).
Newcomb's snail is a freshwater snail belonging to the lymnaeid family. While the details of its ecology are not well known, Newcomb's snail probably has a life history similar to other members of the family. These snails generally feed on algae and vegetation growing on submerged rocks. Eggs are attached to submerged rocks or vegetation, and the entire life cycle is tied to the stream system in which the adults live.
Past & Present:
Predation by the non-native rosy glandina snail (Euglandina rosea) is a serious threat to the survival of Newcomb's snail. This predatory snail was introduced into Hawai‘i in 1955 and has established populations throughout the main islands. Predation on the eggs and adults of native Hawaiian snails by two non-native species of sciomyzid flies represents a significant threat to the survival of Newcomb's snail.
Some of the decline of the snail may be attributed to habitat loss and degradation through water diversion and well drilling. In addition, natural disasters and habitat alteration are threats that imperil Newcomb's snails.
Newcomb’s snail was listed under the Endangered Species Act as threatened on January 26, 2000. On August 20, 2002, critical habitat was designated for the Newcomb’s snail. The designation includes eight stream segments and associated tributaries, springs, seeps, and adjacent riparian areas totaling 1,812 hectares (4,479 acres), and including 19.76 kilometers (12.28 miles) of stream channel. Critical habitat for the Newcomb’s snail includes the six stream locations that are known to be occupied and two sites where snails were observed historically but are now thought to be destroyed.