When Polynesians arrived at the uninhabited Hawaiian Islands thousands of years ago, they found an array of colorful tree snails, each less than an inch in length, across the island of Oahu. Those little snails—there are 41 species in the genus Achatinella—can now be found only on high ridges of the island’s two extinct volcanoes. All the snails in this genus are listed as endangered; many are thought to already be extinct. Their numbers were decimated by a combination of factors, including collectors who wanted the shells, the introduction of nonnative plants and animals, including rats, and loss of the native vegetation—the snails graze on fungus that grows on the leaves of native plants. A conservation project at the University of Hawaii, however, is breeding nine species of Achatinella snails in the lab in an effort to save the creatures.

The Hawaiian Islands, with hundreds of endangered plants and animals, are often called the “Endangered Species Capital of the World.” The islands’ remote location resulted in the evolution of thousands of species that live nowhere else in the world. That specialness, however, confers an added danger, because once a species disappears from Hawaii, it is usually gone forever. – SZ