Ocean Watch

Monday, June 14, 1999

Here’s why they’re
called triggerfish

Last week, I went sailing with friends but after an hour or so, the gusty tradewinds and a big south swell had us calling uncle. We turned the boat around and anchored in a sandy area called the Waikiki bite. Moments later, I jumped into the water with mask and snorkel.

"See anything?" a friend asked after I had been snorkeling a few minutes.

I looked down at the sand and rubble bottom.

"Not much," I said. "Just a bunch of triggerfish."

Triggerfish

Oh, how could I have said such a thing, especially with my boat full of Hawaii newcomers? Triggerfish are some of the most interesting and beautiful fish in Hawaiian waters.

Triggerfish get their name from two moveable spines on top of the fish. When the larger forward spine is upright, the smaller one behind it (the trigger) can drop down, securing the first in place.

Why would a fish want such an elaborate locking system? When frightened, and at night, a triggerfish swims into a hole in the reef just barely big enough to accommodate its body. Once inside, the fish erects its large spine, locks it in place with the second, then extends its pelvic bone from beneath. This wedges the fish tightly into its hiding place.

And I mean tightly. I once met a triggerfish researcher who wanted to find out just how strong these fishes' anchoring system really was. The ichthyologist startled a triggerfish into a tiny cave, then reached in and pulled. And pulled and pulled. The fish died rather than relax its spines.

Another time, a friend told me that she and several acquaintances had been wading in a tide pool when one of them spotted a triggerfish stuck in a hole. They tried for a long time to free the fish but it was firmly trapped. They felt sad, she said, when they had to abandon their rescue effort.

When I explained about these fishes' park-and-lock system, we had a good laugh.

The moral of the story is never try to get a triggerfish out of its hole, especially if it has backed in. Not only will the effort be futile, but your hand is at risk. These fish have powerful jaws and sharp teeth and can deliver a nasty bite if harassed.

Some triggerfish species use their jaws and teeth to crush invertebrate shells, such as those of crabs, snails and sea urchins. Others eat tiny drifting animal life.

There's probably not one longtime Hawaii resident who doesn't know, or at least can't recognize, the Hawaiian name for the reef triggerfish, sometimes called the Picasso triggerfish.

This is because this lovely fish was once Hawaii's state fish (its term expired) and also, because the fish's name is in the song, "I want to go back to my little grass shack ... . "

For newcomers, here's the name: Humuhumunukunuku- apua'a. The first part, humu-humu means to sew, likely a reference to the patchwork pattern of this species.

The second part, nukunuku-apua'a, means snout like a pig. When you take these fish from the water, they grunt like pigs.

Even though we may be accustomed to seeing them, there's nothing ordinary about triggerfish. What I should have said when my friend asked what I saw was, "Get your masks and snorkels on and jump in. There's a bunch of triggerfish here!"