By Guest Blogger Christina Albright-Mundy
Ever wonder where that glorious, sandy beach came from?
Those in the know, know that the oceans are not quiet. Peaceful, tranquil, Zen-inducing, yes — but quiet, no. And it’s not just because of the air being expelled from a regulator. Sea otters bang clam shells against rocks, whales harmone, dolphins whistle and, in warm waters teeming with coral reefs, a constant, static, crunching sound fills the water above 15 feet.
That familiar sound, which rings in the ears of every tropical and subtropical diver, is the gnashing teeth of the parrotfish, which uses a sharp beak to break off bits of coral.
Coral reefs are one of the most diverse ecosystems in the world. Ample sunlight allows the zooxanthellae algae residing inside of the corals to photosynthesize, providing nutrients for coral to grow. The corals provide shelter to a multitude of fish species, juvenile octopus and moray eels. Not all of these fish seek shelter in the coral, however — the parrotfish seeks nourishment directly from the algae found within.
Parrotfish are fascinating to behold. They can live up to seven years and grow to lengths up to four feet. It is their bold coloration, along with their toothy beak, that gives them their name. But if their stunning appearance isn’t enough to impress you, know that these fish also make sand.
Parrotfish are unable to digest coral, so after they digest the algae within, they excrete the undigested coral onto the ocean floor. Think about that the next time you’re sifting for shark teeth or strolling down a moonlit beach.
These remarkable fish also have the ability to change genders. A female fish can function fully as a female, change genders, and then function as a male fish. This is known as “sequential hermaphroditism,” and it is common in the parrotfish world. Male parrotfish maintain large harems of female suitors. But in the event of a male’s death, one of the females will change become a male and assume leadership of the group.
The survival mechanism of some species of parrotfish is also remarkable. Some members of the species will form a mucous cocoon around themselves while they sleep, which scientists think is means of masking their scent from predators. Another school of thought holds that these cocoons serve as protection from parasites while the fish naps. Either way, coming upon one of these fish nestled in their mucous nests is a treat.
Currently, parrotfish are not on any watch lists as being threatened or endangered. They are, however, susceptible to the same stressors that harm endangered marine animals. Ocean acidification negatively impacts the health of coral reefs, which parrotfish rely on for a large percentage of their diet. Overfishing is another concern. While this fish is not commonly eaten, it is considered a delicacy in some parts of the world. The aquarium industry also prizes parrotfish for beautiful markings and colors; however, they typically do not thrive in an artificial environment.
Parrotfish are a keystone species, whose removal from the food chain would have far reaching consequences. Parrotfish keep algae growth in check, which can suffocate coral and reduce the coral’s ability to provide essential habitat to many marine species. And if the population of parrotfish is threatened, so too are those romantic moonlight strolls upon the world’s white, sandy beaches.