The orangespine unicornfish carries two razor-sharp spines at the base of its tail, which it can flare out for defense. Despite its name, and unlike some other Naso species, it doesn't actually have a horn on its forehead.
What defines this group — Reef fish
The bony fish that live against coral and rock: the living backdrop of almost every dive.
A bony skeleton, scales, and a rigid gill cover closing over the gills.
A swim bladder acts as a float: they hold their depth without swimming.
Many change colour, pattern — sometimes even sex — over the course of their life.