Biodiversity #24 – Titan Triggerfish – the largest of the true triggerfish. Though rarely seen by divers, triggerfish have two dorsal spines: the first larger spine is locked in place by the second shorter spine, and it can only be unlocked by depressing the second ‘trigger’ spine. Hence the family name.
Triggerfish are in the order of tetraodontiformes – they only have four teeth in each jaw, which is very powerful and adapted for crushing shells of the molluscs, crustaceans and urchins they eat.
Their mating system is called male-territory visiting polygamy, which means that the male sets up his territory, and any number of females can come visiting (for the spawning period only!) and spawn within his territory. The females stay around the eggs which are laid in, and generally stick to, the sand to guard them, and the male continues to guard his territory.
So, if you have ever been charged by a trigger, and in particular a Titan Trigger, it is likely a female protecting a cone of water above her nest site. The best advice is to swim rapidly in the opposite direction, and horizontally or even downwards, otherwise you may still be in the cone of danger.
Despite its appearance of being mainly ‘a head’, the Titan Trigger is quite powerful and manoeuvrable. It is often seen rearranging the reef so everyone can have a feed – and this even includes swimming backwards as this shot shows.