Octopus Coral

Galaxea astreata

Octopus Coral, scientifically known as Galaxea astreata, is a large polyp stony coral belonging to the family Euphylliidae. Divers can identify it by its sub-massive, columnar, or encrusting colonies, which can grow over two meters across. The coral has a distinctive calcium carbonate skeleton with plate-like corallites that are well spaced and measure 3–4.5 mm in diameter. Its polyps display a range of colors, including pink, grey, green, and brown. This coral is found in the Indo-Pacific region, from Japan to Australia and Egypt to Samoa. It inhabits shallow waters, typically around 15 meters deep, but can be found from 1 to 30 meters. It thrives in clear, saltwater environments, preferring these over turbid or brackish waters. Octopus Coral is a nocturnal feeder, primarily consuming zooplankton and coral larvae. It expands its polyps during the day to feed, making it an effective predator. Reproduction occurs through broadcast spawning, where gametes are released into the water for external fertilization. The coral can be hermaphroditic or gonochoric. Despite its resilience, Octopus Coral is susceptible to bleaching events, such as the one in 1997–1998, which significantly impacted coral populations globally. It is currently listed as Least Concern by the IUCN.