About Hologymnosus annulatus (Lacepède, 1801)
Hologymnosus annulatus has two geographically distinct colour forms: one found in the Indian Ocean and the Red Sea, and the other in the Pacific Ocean. In both forms, females are very dark, appearing almost black, while males are mostly greenish with a blue face. Males of the Indian Ocean form have a white band across the middle of the body, while males of the Pacific form develop a pale area on the caudal peduncle during the breeding season. Male bodies are marked with numerous bluish-red bars, and they often have a pale yellowish bar above the origin of the anal fin. Males have pale purplish heads, with green to blue-green bands that radiate out from the eye; the band that runs toward the snout broadens and branches. Juvenile H. annulatus are very similar in appearance to juvenile Malacanthus latovittatus. Juveniles are brown to olive brown, with 17–19 dark brown bars. They have a blue and black spot on the gill cover, a black spot on the side of each lip (with larger spots on the lower lip), and a large whitish crescent near the end of the tail fin. Hologymnosus annulatus is distributed from the Red Sea, south along Africa's eastern Indian Ocean coast to South Africa, and east to the Society Islands and Pitcairn Island in the Pacific. Its range extends north to southern Japan, and south to the Great Barrier Reef and Rapa Island. This species lives on coral reefs and rocky substrates on offshore reef slopes, at depths down to at least 30 metres (98 ft). Juveniles are normally solitary, and stay near the bottom of the water column, while adults swim relatively high in the water. It is a carnivorous species; its diet consists mainly of small fishes, and it also eats crustaceans. This species is a pelagic spawner.
