Natural History

Color My World

Some fish exhibit drastic changes in appearance as they age.

Story By Suzanne Gerber

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Photos By Barbara Shively

Of all the traits and qualities of a fish’s life, color is the most important. We humans who snorkel, scuba-dive and visit aquariums tend to regard fishes’ colors and patterns as merely aesthetic: things of beauty that enchant and beguile us and always draw us back for more encounters. But to the critters themselves, color is a way of life — a means of protecting themselves from predators, of attracting a mate for reproductive purposes and of signaling advanced stages of maturity. The more we learn about the significance of a fish’s coloration, the great understanding we’ll have of its entire life.

Speaking very generally, a dull-colored fish is primarily concerned with protection, hence his natural camouflage. We see this in even more dramatic fashion when a larger critter (fish or human) approaches and the fish changes color to blend in better with his surroundings. Divers are well aware of this phenomenon. It’s common for one person to spot a well-hidden master of disguise and attempt to point it out to her buddy, only for the buddy to look and look and ultimately throw up his arms in defeat. If only we understood the complex process of nerves and hormones sending lightning-quick messages to layer upon layer of chromatophores and iridophores, we’d marvel at their talent instead of swimming away disappointed.

At the other end of the spectrum are the brightly colored fish. Some wear their flamboyant hues all the time, others flash them only when they’re “in the mood” and need to signal their intentions to their intended. Usually it’s the males who get brighter as they grow friskier, but they’re dancing with death, as their brightness also makes them more visible to would-be predators. This is why it’s a rare (and wonderful) treat to catch a fish, or a pair, positively glowing, looking like they’ve been lit up from the inside. The delightful cowfish, usually a mottled brownish-greenish color, turns iridescent blue-green when he’s hot to trot. When they find their mate, they will encircle each other and rise up high in the water column. But they’re interesting critters — I once saw five of them in a circle dance that seemed shockingly polyamorous.

And there’s the predictable color changing that happens with certain species of fish as they grow and mature sexually. It’s less common than you’d expect for a fish to look totally different as a baby (or juvenile) than as an intermediate, and ultimately as an adult. But the three species we’ve selected for this article do just that — and brilliantly. Barbara and I are like judicious mothers: we love all our fishy babies equally. But truth be told, these three hold a special place in our hearts, and when we find the juvies, we are ecstatic to the point of becoming silly.

Blue tang

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These highly social surgeonfish can be found on their own, but more typically they’re clustered together in a huge school for protection. In fact, with rare exception, they even reproduce in large aggregations. When they do, you can tell the males because their heads and the front of their bodies grow light and slightly iridescent.

When babies are hatched, their initial stage is called the post-larval, and they are truly cute as a button. But you’ll need a fish ID book to see just how adorable, for finding one of these well-protected critters with a naked eye is an extremely rare occurrence. From here, the newborns quickly morph into bright yellow juveniles and are noted for being highly territorial. The males particularly are aggressive toward would-be space invaders. As they grow, their bodies elongate and turn a powdery blue, though their tails remain yellow. At this stage they mix with other species, but by the time they’re about four to five inches long and totally blue, they cluster into small groups comprised only of tangs. Around age two, they lose some of their brightness, become full-fledged adults, and fall in with the foraging groups, where they spend more of their days swimming and grazing.

Tang are extremely curious and friendly fish, and won’t duck and dart when a human eyeball (or viewfinder) is trained on them. I remember before I was a diver, I was snorkeling off a cay in Belize and fell in with a group of possibly 1,000 Blue Tang. They “allowed” me to stay with them for the entire 30 to 45 minutes I was snorkeling. It was a thrill I’ll never forget.

Spotted drum

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You’ll always know when your dive guide has come upon one of these stunners: he or she will stop moving and use both hand to imitate beating on a drum. And while you might never hear it, these little guys actually are emitting a low drum-like sound, produced by special muscles in their swim bladders (hence their name). When you come upon a drum fish, approach slowly. This is a very shy fellow, who’s probably already under a ledge or inside a big crevice in the reef. When he feels threatened, he will beat a hasty retreat and not be seen again.

But when you are lucky enough to catch his little circle dance, you will never want to leave the premises. He’s been likened to an expectant father, pacing back and forth, and for good reason. Because his coloring is flamboyant, camouflage isn’t really an option, so he stays close to the base of a coral or opening of a cave, into which he can dart in a split second. As a youngster, the drummer sports very elongated dorsal and anal fins, which flit in the water like the tiniest sailboat.

As a new juvenile, the drummer has only got stripes, until he reaches the intermediate stage, when his body grows longer, the fins get re-proportioned, the stripes become horizontal as well as vertical and the first of the spots appear. He’s still a looker, but divers are already pining for his baby days. As an adult he can grow to nine inches, but he’ll stay solitary, except to mate. Though he’s a member of the same genus as the jackknife fish or high hat (and similar-looking), don’t confuse this unique fish with his less exotic cousins.

Trunkfish

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Part of the irresistible family of boxfish, the Trunkfish is a common sighting in the waters surrounding Turks & Caicos, as well as the greater Caribbean. But once you catch sight of a tiny, pea-size baby, you will agree there’s nothing “common” about this guy at all!

What’s notable about this fish (either the smooth or spotted Trunkfish) is the shape of his little body (six to twelve inches at full maturity). It’s enclosed in bony armorlike plates (called, as with a turtle, a carpace). Only the mouth, eyes, fins, and vent are exposed from the triangular, box-like shape. Hard as their bony skeleton is, they’re actually feathery-soft on the outside.

When a Trunkfish is first hatched, you will think you’ve happened upon a tiny, polka-dotted die bouncing in the water. At Grand Turk, where Barbara and I have enjoyed many wonderful dives, we’ve specifically asked our dive guides to do the nearly impossible and find a new baby upon demand so we can giggle underwater and Barbara can get the ultimate shot. It defies probability, but in my experience, every time I’ve requested a trunk “ball” (as I like to call them), I’ve been rewarded.

Young Trunkfish have a more rounded body and may exhibit brighter colors than the sedate brown adult. Because of their shape and scale structure, these little guys swim relatively slowly and use a rowing fashion. Don’t try to catch one, though: even the slowest trunk swims two to three times faster than we can.

New York-based Suzanne Gerber writes about scuba, travel and health for a variety of publications. Book your next dive trip at www.worldofdiving.com.

Avid underwater photographer Barbara Shively discovered Grand Turk diving in 1997 and has returned every year. It is her passion to share the coral reefs’ beauty with friends and family through her photographs. See her work at: shivelygallery.home.comcast.net.



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Marta Morton, owner/operator of Harbour Club Villas (www.harbourclubvillas.com) took this photo of the native Turks & Caicos rock iguana on Bay Cay. This endemic animal is being threatened by the invasive green iguana. See article on page 36.

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