Natural History

Crunch ‘n’ Munch

Stoplight Parrotfish

Stoplight Parrotfish supermale

Besides transforming their appearance, parrotfish turn reef into sandy beach.
By Suzanne Gerber ~ Photos & Captions By Barbara Shively

It doesn’t matter whether you call them perroquetfeu, loro colorado, Budião-Vermelh, sparysoma szmaragdowa, or parrotfish, these beautiful creatures are among the most beloved in the underwater menagerie. Nor does it matter whether you speak French, Spanish, Portuguese, Polish or English. It’s not hard to puzzle out how the parrotfish got its avian appellation: those bright colors and prominent, beak-like teeth.

Stoplight Parrotfish initial phase

Stoplight Parrotfish initial phase

Here in the Caribbean we don’t have the jumbo-size species like the bumphead or humphead parrotfish, which can grow to more than four feet and tip the scales at more than 100 pounds, but we do have dozens of dazzling species. And when you learn a little more about these amazing creatures, you will start to appreciate them on an even, um, deeper level.

Front and center

Redband parrotfish varied colors and patterns

Redband parrotfish varied colors and patterns

One of the most striking things about this family of fish is how dramatically its members change color (and change sex! But more on that later) and how different the same fish will look when’s he’s a juvenile, a teen and finally a mature adult. Barbara’s photos are not only beautiful, but they’re highly instructive, and the captions clearly illuminate specific color changes, which makes it (relatively) easy to determine where in his life cycle any given loro colorado is.
And those teeth! They’re not just an amusing spectacle. They perform an important function in the perroquetfeu’s life. These chompers, which actually form a bill, are used to gnaw off pieces of coral. Yet it’s not the crunchy coral skeleton that they’re after: it’s the polyps that grow on the surface and contain the nutritious zooxanthellae algae.
The coral-munching serves an additional purpose for these clever critters. Many species have a second pair of (flat) teeth inside their throats, to help them grind down the coral, which then passes through their system and is eliminated in heaps that resemble sand piles. But these droppings aren’t random. Like Hansel and Gretel’s bread crumbs, they are strategically dumped, if you will, to help the parrotfish navigate their way to and back from their nocturnal nests. It’s hard to fathom, but parrotfish can produce up to one ton of coral sand per acre of reef every year. And, notes Jodi Johnson, an environmental officer in the TCI’s Department of Environment & Coastal Resources on Grand Turk, “It comes out nice and crumbly, which helps to make and maintain some of that  beautiful sand and shoreline that we and our visitors love to walk on.”

Nocturnal nests

Redtail Parrotfish various stages

Redtail Parrotfish various stages

Night divers love to learn about fishes’ after-hours activities. And one of the most unique behavioral patterns is the parrotfish’s nighttime cocoon, which is made of a slimy mucus that’s produced by their skin glands. This half-hour-long show starts every night at sunset. The coating smells rank, but that’s actually a good thing (well, if you’re a parrotfish). In addition to the physical protection the cocoon provides, its smell is an additional deterrent to would-be predators. There’s an opening in the front with a flap that lets water in, and another at the back that lets it out, allowing the fish to breathe, though the rate is greatly reduced during sleep. Once his morning alarm goes off, the fish spends another half-hour breaking out of his cocoon before heading to work.
Parrotfish are famously adept navigators, returning night after night to the same slumber ledges or “caves.” And when they’re frightened during daylight hours, they make a beeline for those quarters. The accuracy of this behavior piqued researchers’ curiosity enough to lead a group to study it. First, they covered the opening of the cave with a net and then agitated the fish. Result: the fish swam into the net and waited until it was eventually lifted. When clouds would cover the sun or when the scientists intentionally “blindfolded” the fish with removable suction cups, they would swim in the wrong direction. But every time they had their vision in full light, the fish reached their sleeping quarters swiftly and directly, leading the researchers to assume vision plays an integral role in their navigation.

Sex lives of Parrotfish
Unlike homo sapiens, who have countless ways to court and romance, scarus ceruleus have but two styles of reproduction. Parrotfish spawn year-round, though they seem to favor summer months. (And one fussy variety, the Redbill, does it only in the afternoon. Don’t ask.) Of the two basic reproduction “techniques,” the first requires large assemblies, where mostly males move away from their feeding grounds into 65 to 70 foot water. Periodically, 4 to 13 males will leave the pack and swim upward, releasing into the water both eggs and sperm (technically called milt, which is a fluid containing the sperm). The second technique (the more romantic one, in our book) involves one male and one female swimming upward together in the water column, circling each other, then releasing egg and sperm in a cloud that resembles milk. A day later this will hatch, and out will swim more females than male, though they are indistinguishable at this stage. Some males will mature into small adults and be called primary males. Others will grow larger and be called secondary, which tend to be solitary and dominate a sexual territory—and their very own “harem.”
Perhaps the most fascinating thing about our friend the sparysoma szmaragdowa is this whole sex-change business. Parrotfish are born with both sets of sex organs and can start off as either gender. Those born male will stay male, though they’ll never become what’s called a dominant male. Interestingly, that role is played by fish that start off female and morph into a supermale (usually when male populations begin to dwindle). These large fish, called terminal-phase males, have bright, distinctive markings and colors, which attract the females. (In courtship, the supermales’ colors grow even more brilliant.) Sex change in parrotfish ensures there will always be a male to reproduce with all the females. And that’s important to the species and to us, because who could imagine coral reefs without its brightly colored birds?

New-York based Suzanne Gerber writes about scuba, travel and health for a variety of publications.

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 through her photographs, many of which can be viewed and purchased at http://shivelygallery.com. A variety of her prints are on sale at Art Provo, located in The Regent Village, Providenciales.



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Hobbyist photographer and Assistant Director for Research & Development at the TCI Department of Environment & Coastal Resources Dr. Eric F. Salamanca took this rare photo of a Bahama Woodstar hummingbird enjoying the nectar of Moringa flowers.

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