Calotomus carolinus

Female specimen

The species is about 50 centimetres (20 in) long. The species changes its appearance greatly during the transition to adulthood. Juveniles of the species are typically a mottled orangish-brown, with some pink shading. Adult males of the species are shades of blue or green, and have pink lines radiating from their eyes. Adult females are mottled brown and their eyes bulge out slightly.[3][4] Its jaws consist of pebble-like teeth fused into a beak for eating seaweed, but in juveniles the teeth are not yet fully fused and are visible on the outside of the dental plate.[4][5]

Calotomus carolinus has a wide Indo-Pacific distribution from the coast of East Africa, although not in the Red Sea where it is replaced by Calotomus viridescens, through the Indian Ocean to the eastern Pacific Ocean around the Revillagigedo and the Galapagos Islands.[2]

Calotomus carolinus can typically be found as a single fish or in small groups, in shallow reefs or lagoons.[3][5] It occurs in subtidal reef flats, lagoons and seaward reefs down to depths of 27 metres (89 ft), or more. Within the wider habitat this species can be found in areas of coral, rubble, seagrass and weeds. It feeds on a variety of benthic encrusting algae, Padina and seagrasses. It is a protogynous hermaphrodite and it may have no initial phase males and there might only be terminal phase males.[2]

Calotomus carolinus was first formally described as Callyodon carolinus in 1840 by the French zoologist Achille Valenciennes (1795-1865) with the type locality given as the Caroline Islands.[6] When Charles Henry Gilbert described the genus Calotomus in 1890 he designated Calotomus xenodon as its type species, thinking that the genus was monotypic, this was later shown to be a synonyms of C. carolinus.[7]

• Photos of Calotomus carolinus on Sealife Collection

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