The 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).
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
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 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.