List of threatened and endangered arthropods, including insects, arachnids, and crustaceans under the United States Endangered Species Act as of October 2013. Key to Listing Status codes: E - Endangered. An animal or plant species in danger of extinction throughout all or a significant portion of its range. T - Threatened. An animal or plant species likely to become endangered within the foreseeable future throughout all or a significant portion of its range. SAE or SAT - Listed as Endangered or Threatened due to similarity of appearance. A species may be treated as endangered or threatened if it resembles in appearance a species which has been listed and enforcement personnel would have difficulty distinguishing between the listed and the unlisted species; if the effect of this difficult