Acanthastrea pachysepta

Acanthastrea pachysepta is a coral species found primarily in the Indo-West Pacific region, including areas from the Maldives and Indonesia to Melanesia, extending north to Taiwan and south to Australia. This coral thrives in tropical climates and is typically associated with reef environments, particularly protected upper reef slopes and lagoons. Divers can encounter this species at depths ranging from the surface to 30 meters, with most occurrences recorded at depths shallower than 20 meters. The coral forms flat or hemispherical colonies, which can be phaceloid or partly flabello-meandroid in structure, and rarely exceed 0.5 meters across. Its corallites are distinctive, measuring 40 to 50 mm in diameter and varying from circular to irregular shapes. The primary septa are thick and feature 3 to 5 long lobed teeth, while the columellae are large and often diffuse. The coral's coloration is typically dark green or gray, with yellowish primary septa providing a subtle contrast. In terms of reproduction, Acanthastrea pachysepta belongs to the class Anthozoa and can be either gonochoric or hermaphroditic. Mature gametes are released into the coelenteron and spawned through the mouth. The zygote develops into a planktonic planula larva, which undergoes metamorphosis before settling. Despite its resilience, the species has a high bleaching level and estimated mortality in certain areas like Palau. It is currently listed as Least Concern on the IUCN Red List.