Marine Wildlife Encyclopedia
Queen Triggerfish Balistes vetula
The queen triggerfish is a roughly oval-shaped fish, with small eyes located at the top of the head, a large dorsal spine, large triangular dorsal and ventral fins at the rear of the body and a crescent-shaped tail. The body is greenish blue with a yellow to purple belly, and fine black lines radiating from the eye as well as two thick blue bands running from the mouth to the edge of the gill cover. Sexes appear similar, and juveniles possess short fins and are paler than adults.
The queen triggerfish is a carnivore specialized in eating hard-shelled prey such as urchins, lobsters, crabs and shellfish. Being a fairly large and aggressive fish, the queen triggerfish is fed upon only by larger reef predators such as grouper, jacks, sharks and occasional reef visitors such as tuna and marlin.
The queen triggerfish employs a special technique to get to its favourite food – the sea urchin – while avoiding the worst of the prickly spines. The triggerfish will daintily grasp a spine in its mouth, lift the urchin up off of the seafloor, and drop it so the vulnerable underside will be exposed. Triggerfish have also been observed blowing water out of their mouth at urchins in an attempt to knock them over.
Queen Triggerfish Feeding Behaviour
Queen triggerfish are carnivores possessing strong jaws for eating hard-shelled prey including lobsters, crabs, shellfish, and especially urchins. Queen triggerfish hunt actively during the day. They flutter their fins or blow water from their mouth to stir up sand, and even pick up and move rocks, in order to uncover hidden prey. In order to tackle their favourite food – sea urchins – queen triggerfish may pick the urchin up by the spines and drop them. While the urchin is falling through the water, the triggerfish quickly attacks the exposed, vulnerable underside where the spines are short. Queen triggerfish can also blow water under urchins to flip them upside-down, once again exposing the vulnerable underside.
Attack & Defence Behaviour in Queen Triggerfish
Queen triggerfish are fiercely territorial during the breeding season, when they guard their eggs, and will aggressively chase and bite intruders. Queen triggerfish also possess specialized membranes behind their pectoral fins, which produce a throbbing sound audile to most other fish that warns them to keep away. At night, triggerfish hide in crevices and lock their dorsal spine into an erect position, making it very difficult for predators to pull them out. This spine and their awkward shape also make queen triggerfish difficult for most predators to swallow.
Queen Triggerfish Reproductive Behaviour
Queen triggerfish reproduce sexually by laying demersal eggs, and do not undergo sex change during reproductive development. During the breeding season, males establish territories roughly 10 m (33 ft) in diameter and attract several females. Nests are built in the sand by fluttering the fins or blowing water from the mouth near the bottom to create wide sand bowls into which eggs are laid following an unknown courtship ritual. Once the eggs are laid, both parents defend an area described as an inverted cone above the nest, and they have been known to bite divers who come too close. Once the eggs hatch, the young disperse into the current. Reproduction is thought to occur year-round with peaks in the fall around September and again in the winter around January. Whether the queen triggerfish prefers to spawn at a certain time of day is currently unknown.