Sharp teeth, aggressive ways turn triggerfish into a terror

TAHAA, FRENCH POLYNESIA » Here in the Society Islands, I swim with black-tipped reef sharks, free-dive on giant moray eels and float inches above venomous, spine-waving sea urchins, all without worry. But when I come face to face with a titan triggerfish, I pay attention. Snorkelers and divers do not mess with these mamas.

Triggerfish get their name from a fin on the back that the fish can raise and lock in place with a shorter second fin. At the first sign of danger or to bed down for the night, the triggerfish ducks into a hole in the reef, raises its trigger and locks in.

Years ago a triggerfish researcher told me a memorable story. Wondering how strong the spines were on a reef triggerfish (known in Hawaii as the humuhumu­nukunukuapuaa) and how long the fish would keep its trigger up when threatened, he reached into the hole, grasped the body and pulled. And pulled. The fish died locked in.

The researcher did his experimental tugging from the tail end because a triggerfish’s other defense is a pair of strong jaws and 14 chisel-sharp teeth.

Triggerfish use their formidable teeth to crunch up snails, crabs and sea urchins. Females also use their teeth to defend their fertilized eggs.

Among damselfish, blennies and some other reef fish, the males defend nests. Male triggerfish, however, have harems, making egg protection at each site impossible.

Offspring defense is therefore left to the females, which, like all mothers, take the job seriously. Get close to an egg patch, and female triggerfish of all species will charge and bite.

Such high security requires high energy, but guard duty doesn’t last long. Female triggerfish lay eggs and males fertilize them at dawn. The larvae hatch the next night.

The well-named titan triggerfish, not found in Hawaii, grows up to 30 inches long. This beefy giant is more than twice the size of Hawaii’s common triggerfish.

It’s easy for snorkelers and divers to know where a triggerfish’s eggs lay. Get too close and a titan triggerfish female will make a high-speed bluff charge or two before she bites a leg or attacks a camera.

After coming face to face with the teeth-baring titan triggerfish in this photo, I heeded her unmistakable message. I left the area to snorkel with safer reef residents, sharks, eels and urchins.

Reach Susan Scott at www.susanscott.net.