Hawaiian Black Coral

• Despite its name, the living coral is not black: what is black is the internal skeleton, seen only once the colony dies or is harvested.
• It is the official state gem of Hawaii, and its harvest for jewellery is regulated with quotas and minimum sizes because of how slowly it grows.
• Black corals grow a few centimetres per decade, and colonies of other species in the group have been dated at thousands of years old.
• This is the black coral of Hawaii, the state's official gemstone, and it supports a multi-million-dollar fishery employing more than 500 people.
• The order's name, Antipatharia, comes from the Greek anti and pathos: against disease. The ancient Hawaiians used ekaha ku moana medicinally.
• Its skeleton is not calcareous but made of protein and chitin, black and so hard that it polishes like a gemstone.
• It lives between 12 and 75 years according to radiocarbon data, but other black corals are among the longest-lived organisms on the planet: a Leiopathes from Hawaii was dated at 4,265 years.
• Depth was thought to protect it from harvesting, but that has been called into question by detected falls in biomass.
• The species is named after Richard Grigg, the biologist who studied this fishery and laid the foundations of its management from the 1960s onwards.

Habitat & environment

Deep rocky bottoms and walls of Hawaii, between 30 and 120 m

Sources consulted: Opresko (2009); Wagner et al. (2012), Coral Reefs; Roark et al. (2006); Grigg (1974, 2001)