To bring the tiny Newcomb's snail off the endangered species list, the U.S. Fish and Wildlife Service says it needs additional scientific information, as well as the protection of Kaua'i's free-flowing streams.

In a recovery plan on the freshwater snail, the service said a total of 6,000 to 7,000 of the quarter-inch black snails survive in 10 regions of six streams, where they feed on algae on rocks. They attach their eggs to rocks under water or to vegetation in the streams.

The animals, known to science as Errina newcombi, gravitate to springs along streambeds.

"Their entire life cycle is tied to the stream in which they live," the service said in a press release, and that one key to their survival is to maintain flows in mountain streams.

There are also problems with non-native predators. Green swordtail fish, American bullfrogs and the cannibalistic rosy glandina snail all feed on Newcomb's snails, the service said.

Patrick Leonard, field supervisor for the service's Pacific Islands office, said that while the snails are small, they play a role in both the biology and culture of Hawai'i.

"Often our attention is focused on charismatic Hawaiian species such as the nene and monk seal while the lesser-known species remain in relative obscurity. No matter the size and appearance, each species plays a significant role in preserving the biological and cultural integrity of Hawai'i. The Newcomb's snail is no exception, and this plan will help preserve the species and hopefully garner it much-needed attention and interest," he said.

The snail recovery plan is available at www.fws.gov/pacificislands/.

Reach Jan TenBruggencate at jant@honoluluadvertiser.com.