No matter how humble or obscure, all plant, animal and insect life in America is eligible for protection under the Endangered Species Act, one of the most far-reaching and important conservation statutes in the world. Arachnids, birds, corals, crustaceans, flatworms and roundworms, mammals, reptiles, sponges, trees, algae ... all species, great and small. The ESA turns 50 this month, and if beating extinction is the measure, the law has been a success. Of the more than 1,600 U.S. species listed for protection since the act's inception, 99% have been rescued from the oblivion of extinction. And...