Queen triggerfish  (Balistes vetula)

The deep-bodied queen triggerfish has suitably regal colouring; it is a flamboyant, and variable, mixture of blue, green and yellow, which can be light or dark depending on the fish’s mood (3), and vivid blue lines pattern the head and the fins (2). Triggerfish are named after the spines situated on their backs. The first large spine can be erected and then locked into place by the second smaller spine which fits into a groove in the first spine (3). This clever locking mechanism enables triggerfish to wedge themselves into crevices when they feel threatened (3), and the first spine can only be folded away when the second ‘trigger’ spine is depressed (2). The eyes, which are set high on the fish’s head (2), are capable of moving independently of each other (4), and the small mouth bears large, stout teeth (2).