Tag Archives: jacks

Little cleaner wrasses offer spa experience to other fish

Published August 20, 2016 in the “Ocean Watch” column, Honolulu Star-Advertiser ©2016 Susan Scott
A cleaner wrass with an island jack customer. ©2016 Susan Scott

A cleaner wrass with an island jack customer. ©2016 Susan Scott

Last week, in about 7 feet of water, I swam over a reef wall and found myself in the middle of a dozen jacks, a new species to me, each bearing yellow, dashiki marks on their sides.

Having a monster in their midst caused the fish to dart up, down and around, but surprisingly they didn’t flee. When I backed off, I saw why. The jacks were waiting for a turn at the spa.

Reef spas are run by narrow, 4-inch-long fish called cleaner wrasses. A variety of fish pick goodies off other fish for food, but only the cleaner wrasse sets up a service station. It’s a one-stop shop for pest removal, wound debridement and massage.

The wrasses work alone, in pairs or in teams up to five. To advertise their business, the little fish bob their neonlike bodies up and down. The front half of the fish’s body is a glowing yellow, and the rear half is purple with lavender edges. A black stripe runs from eye to tail, accentuating the fish’s bright colors.

You can’t tell a male from a female cleaner wrasse by color, but you can tell a juvenile from an adult because young cleaners are nearly all black. The kids get their grown-up colors early on, when they’re only about an inch and a half long. If a cranky adult chases away a little wrasse sporting its new colors, the youngster can change back to black and safely move to a friendlier neighborhood.

When I first learned about cleaner wrasses while studying biology at the University of Hawaii, the fact that Hawaii hosts an endemic species was so emphasized that I thought the little service fish was a Hawaii-only phenomenon. Later, though, I saw similar cleaner wrasses on just about every reef I visited in the tropical Pacific. The Hawaiian cleaner wrasse, it turns out, is only one of five species in the Indian and Pacific oceans. Ours, though, is the prettiest.

Not all fish that visit wrasse cleaning stations have parasites or dead skin that’s bugging them. Researchers believe that the sensation of the wrasses’ fins wiggling against the skin feels good to their clients. Big fish sometimes come just for a back rub.

The jacks I saw lining up for a rubdown are a rather rare species here. Called island jacks, yellowspot trevally or ulua, these silvery fish with yellow side spots usually school in deep water but sometimes come inshore. They grow to about 28 inches.

I’d never before seen a school of island jacks or watched any jack hold perfectly still with mouth and gill covers open while a cleaner wrasse worked it over. That’s why I don’t mind snorkeling in the same seemingly unremarkable places over and over. I never know what I’m going to get, and it’s always an adventure.

Coloring book educates about Pacific coral reefs

Published September 8, 1997 in the “Ocean Watch” column, Honolulu Star-Advertiser ©1997 Susan Scott

 When the Hawaiian Islands Humpback Whale National Marine Sanctuary was created in Hawaii, some people argued we didn’t need it. “Why add a federal agency to protect that which is already protected?” they asked.

There were several good answers, but one that rang clear was the promise of marine education. Federal dollars, proponents said, would go into much-needed teaching programs about preserving our humpback whales and their habitat, the ocean.

One product of that promise is the Pacific Coral Reef Coloring Book, one of the sanctuary’s responses to 1997 being designated the International Year of the Reef.

This is no run-of-the-mill coloring book: The text, written on the left, explains coral reef biology and ecology in English, Samoan and Hawaiian. The pictures, on the right, were drawn by Hawaii resident Kathleen Orr and have a distinct local flavor.

Here are some facts I learned from this book:

  • The reefs with the most biodiversity (different kinds of plants and animals) are in the far western Pacific and southeast Asia. The farther you go from this rich center, the fewer species you see.

Australia, close to this coral core, has about 2,000 species of fish. American Samoa, farther away, drops to about half that with 1,000 fish species. And Hawaii, thousands of miles away from the coral reef center of the world, has less than 500 kinds of fish.

  • Triton’s trumpet snails (whose shells you see in every souvenir shop from here to India) are great allies of the coral reef, both in life and in death.

In life, one of the trumpet snails’ favorite meals is the crown-of-thorns starfish, a species notorious for eating coral. After death, the trumpets’ enormous shells provide homes for equally enormous hermit crabs. Crabs are scavengers that clean the reef floor of dead plant and animal material.

We can help the reefs by never killing snails for their shells nor buying such shells in shops.

  • Jacks, called ulua in Hawaiian, are often seen on coral reefs. For these strong swimmers, the reef is a hunting ground.

In contrast are butterflyfish, commonly seen on coral reefs. Some species spend their entire lives near a single clump of coral.

The sanctuary has come through with its promise of marine education. Now all we citizens have to do is take advantage of the offer.

To request these free coloring books, call 541-3184 on Oahu, 879-2818 on Maui.