The yellowhead wrasse can grow to about 19 centimetres (7.5 in) in length. Both its sex and its appearance change during its life and the colouring at each stage is rather variable. As a juvenile it is mainly yellow with a lateral bright blue stripe. In its next phase while it is female it has a dark coloured back, sometimes with bluish shadings, and a yellow underside. Two short wavy dark lines radiate from the hind edge of each eye. Later, as an adult male, the head and front part of the body are yellow, the hind half of the body is silvery grey and there is a vertical black bar and a broad black stripe along the ridge of the back. It still has the characteristic dark wavy lines near the eye. The dorsal fin has 9 spines and 11 soft rays and the anal fin has 3 spines and 12 soft rays.
The yellowhead wrasse is common on coral and sandy reefs and among rocks at depths down to about 80 metres (260 ft). It feeds on small invertebrates including crabs, shrimps and sea urchins. It has prominent teeth that help it to grasp crustaceans and to lever prey items off rocks.
Like many other wrasses, the yellowhead wrasse is a protogynous hermaphrodite, starting life as a female and later becoming a male, changing sex when it is about 7 centimetres (2.8 in) long. Mature males are territorial during the breeding season and gather in a lek. There is a daily migration from feeding grounds to spawning sites and large males tend to monopolize mates.
The yellowhead wrasse is often found associated with foraging goatfish, Pseudupeneus maculatus and Mulloidichthys martinicus. These dig in soft substrates where they locate prey with the help of their chemosensory barbels and the yellowhead wrasse is adept at snapping up some of the disturbed invertebrates. The yellowhead wrasse has also been observed to behave aggressively towards yellowhead jawfish, Opistognathus aurifrons, harassing them and entering their burrows.
Interactions with humans
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