Some corals are gonochoric, meaning each individual is one sex, either male or female. Others are hermaphroditic, meaning they are both sexes, either at the same time (simultaneous) or one sex becomes another at some point in their life history (sequential if the switch happens once or a few times, or cyclical if it’s a continuous cycle).

Lophelia pertusa is gonochoric, with all of the polyps on a colony being the same sex, so we can say that a colony of Lophelia is either male or female. In some shallow water reef-building corals the polyps on a single colony can be different sexes, but this hasn’t been found in any deep-water species as yet. Caryophyllia cup corals are the only cold-water corals found to date that are hermaphrodites, though this life history strategy is common amongst tropical corals.