When you think of a Stoplight Parrotfish, you might think of a bird, but no, it’s a fish. They can grow up to 2 feet. Females and younger adult males have mostly blue-gray body scales outlined in dark gray, a reddish belly, tail, and fins. Colorful terminal-phase males are mostly green, with blue and reddish horizontal stripes on their head and lower ventral body, and yellow and blue markings on the tail, which is shaped like a crescent moon. When they adapt parrotfish retire to the reef bottom to sleep at night. Some burrow into the sand like wrasses while some species of Scarus have developed the ability to secrete a filmy mucus cocoon. Some individuals also produce mucus cocoons under anoxic conditions. The mucus envelope is secreted in thirty minutes and masks its scent, affording the parrotfish protection from coral reef night predators such as sharks and moray eels. Six series of experiments were performed to determine the effectiveness of the mucus envelope in a reduction of predation using the common spotted moray eel and three species of parrotfish. Only one of the parrotfish (Scarus croicensis) was capable of secreting a mucus cocoon. The results indicated an increased tendency for the moray eel to prey on the species of Sparisoma (apparently do not secrete mucus cocoons) rather than Scarus croicensis. The moray uses the senses of smell, taste, and touch in its feeding activities. A grasping reflex is initiated and the food is swallowed immediately upon touch. In these experiments, the grasping reflex was not initiated when the head of the moray was exposed to the mucus.

 

The herbivorous parrotfish can be distinguished from other Bahaman reef fish by their size combined with colorful appearance, large and heavy scales in regular rows on the head and body, and beak-like mouth. The unusual mouth in which their teeth are fused together to form a beak-like jaw bears strong resemblance to that of the tropical bird, and hence, is how their name was derived. They possess a unique pharyngeal dentition in which the upper interlocking pharyngeal bones located above the gills rest plush against the lower pharyngeal bone to form the pharyngeal mill (can be thought of as molar-like teeth in their throats). This mill is used to grind up the hard coral skeleton that contains microscopic algae called zooxanthellae (gives coral its color) on which parrotfish feed (Davidson, 1998). The crushed calcareous material travels through the fish's digestive system and is voided on the reef as white coral sand. Some fish will return to the same location to deposit this calcareous powder resulting in the formation of small hills over time. A study on a Bermuda reef reported that parrotfish produce an estimated one-ton of coral sand per acre of reef per year. They make a living by eating coral. They also live in coral reefs.

 

They do well in there ecosystem because they technically live in their food and create sand. They are found in Florida to Brazil, Bermuda, West Indies. Stoplight parrotfish have a big population. Their population is also growing. Their population is so big because they mate all year long. These herbivorous reef fish graze on corals and algae growing on the surfaces of rocks throughout the reef. The strong beak-like fused teeth are used to bite off pieces of stony corals. It is not the hard coral skeleton that provides nourishment, but rather the coral polyps that grow on the surface of this skeleton. Living within these coral polyps are symbiotic algae called zooxanthellae. Coral skeletal material that is ingested by the parrotfish is crushed by the grinding motion of the pharyngeal mill, specialized teeth located in the throat. Afterwards, it makes its way through the fish's digestive system and deposited on the reef as white coral sand.

 

Parrotfish are known to return to the same area to release their waste products, forming hills of white sand. Parrotfish may produce as much as one ton of coral sand per acre of reef each year. They do not need to compete for food because they eat algae and there is enough algae to go around. So therefore there is no competitors either. Snappers, jacks, and moray eels as well as other carnivorous fishes feed on the stoplight parrotfish. Stoplight parrotfish evade being eaten by hiding among the coral. Some interesting facts that I learned are that they change gender. They have to change both sex and color to become male, and they create sand from their waste.

 

Author: Baylee L

Published: 05/2009

 

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