The Peculiar Parrotfish

Of the approximately 5,000 different species of reef fish that inhabit Caribbean waters, perhaps one of the best known is the Parrotfish. There are many species of this beautifully colored fish, found not only in the Caribbean, but also throughout the Atlantic and Pacific oceans. Like other fish found in the sea, parrotfish possess many curious qualities that have baffled scientists for years.

Named for an odd-looking beak that resembles that of a parrot, this fish plays an important role in maintaining the health of the reef. Parrotfish can be found eating the algae off the surface of the reef, and occasionally they are found eating directly on the coral. For years, scientists believed parrotfish were destroying the reef, but recent studies have proven that when parrotfish are prevented from feeding along an area of the reef, the coral is "smothered" to death by the growth of algal mats. The grazing activity of parrotfish keeps this in check. In fact, it seems that these fish evolved their strong beak-like jaws and teeth primarily for the purpose of grinding up pieces of coral. Parrotfish have molar-like teeth in their throats that chew up coral so that stomach acid can digest the algae found in and around the coral. This ground up coral is released as sand, creating the sandy bottom and white beaches found in and around coral reef ecosystems. Unbelievable as it may sound, one parrotfish is capable of creating one ton of sand a year!

Reef Brief is a weekly column published in the San Pedro Sun

After spending the day in a school of other parrotfish feeding on algae, seaweed, and coral, each fish separates at night to search for dwellings in which to sleep. When the parrotfish has found a place to nest in the coral, it begins to secrete a sticky mucous forming a transparent cocoon around its body. This unusual process takes up to thirty minutes to complete and another thirty minutes is needed to get out of the cocoon in the morning. Scientists were puzzled by this activity, but it is now believed that the cocoon helps to protect the fish from predators by masking the scent of the fish.

Another curious feature of parrotfish is that throughout their lifecycle, these fish change their sex. A sexually mature female parrotfish will lay its eggs, eventually to be fertilized by males. As the females ages, she will transform into a male, a change made apparent by a color transformation, in which the light female will turn into a dark male. The evolutionary explanation behind this sex change is that many of these fish die young so there is a need for many females to release eggs and only a few males to fertilize them.

Parrotfish are an excellent example of animals that have evolved traits, peculiar as they may be, to help the survival of the species. As with other reef fish, parrotfish greatly depend on the reef for food and protection. Likewise, the reef greatly depends on parrotfish to maintain its health. So, the next time youāre snorkeling or diving donāt be alarmed by the munching sound you may hear- itās just a parrotfish doing its job.

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