Staghorn (seen here) and elkhorn corals are listed as Threatened under the Endangered Species Act. They are the only coral species currently listed, but 66 other coral species have been proposed for listing and are under review. Both staghorn and elkhorn coral are found in Caribbean waters and generally do most of their reproduction when bits of their branches break off and reattach somewhere else. They also can spawn to reproduce, but only do this in a carefully timed broadcast once a year. See more endangered ocean species in our slideshow.