Under the Endangered Species Act, a species may be listed as either threatened or endangered depending on their risk for extinction.

The Endangered Species Act (ESA) defines an endangered species as “any species which is in danger of extinction throughout all or a significant portion of its range.” Endangered species are automatically protected by prohibitions of several types of “take,” including harming, harassing, collecting, or killing, under Section 9 of the ESA. There are some limited exceptions to these rules listed in Section 10 of the ESA. The Kemp’s ridley turtle, considered the smallest marine turtle in the world, is listed as an endangered species throughout its range of the Gulf of Mexico and entire U.S. Atlantic seaboard.

The ESA defines a threatened species as “any species which is likely to become an endangered species within the foreseeable future throughout all or a significant portion of its range.” Threatened species receive protections through separate regulations issued under Section 4(d) of the ESA. These regulations occur separately from the listing and detail what take prohibitions are in effect. Also called 4(d) rules, they can include the same prohibitions under Section 9. Elkhorn coral – a large, branching coral with thick and sturdy antler-like branches – is listed as a threatened species throughout its range.

NOAA scientists use the best scientific and commercial information available as the basis for their listing decisions. Scientists may not consider the economic impact of listing a particular species. A species must be listed if it is threatened or endangered due to any of the following five factors: