parrotfish

Parrotfish are mostly tropical, perciform marine fish of the family Scaridae. Abundant on shallow reefs of the Red Sea, Atlantic, Indian and Pacific Oceans, the parrotfish family contains ten genera and about 90 species.

Characteristics

Parrotfish from North coast East Timor‎.

Parrot fish are named for their dentition; their numerous teeth are arranged in a tightly packed mosaic on the external surface of the jaw bones, forming a parrot-like beak which is used to rasp algae from coral and other rocky substrates^[1] (a process called bioerosion). Many species are also brightly coloured in shades of blue, green, red and yellow, but are not especially popular as pets.

Although they are considered to be herbivores, parrot fish eat a wide variety of organisms, that live on coral reefs. Some species, for example Bolbometopon muricatum may include corals (polyps) in their diet.^[1] Their feeding activity is important for the production and distribution of coral sands in the reef biome and can prevent algae from choking coral. The teeth grow continuously, making it hard to curb overgrowth in the aquarium. Ingested during feeding, coral rock is ground up by the pharyngeal teeth. After they digest this it is excreted as sand thus at times creating small islands and the idyllic sandy beaches of the Bahamas and Caribbean. One parrot fish can chew coral into 90 kg of sand each year.^[2]

Maximum sizes do not vary widely within the family, with the majority of species reaching 30 centimeters to 40 centimetres (16 in) in length. However, a very few species, such as the bumphead parrot fish , are much larger, up to 100 centimeters.^[1]

Their bodies are deep, with large, thick cycloid scales, large pectoral fins and homocercal tail fins. The pectorals are the parrot fish's primary means of locomotion, the tail only used when speed is required. Some parrotfish females can turn into male parrot fish.

Life cycle

Bicolor parrot fish (Cetoscarus bicolor)

The development of parrot fish is complex and accompanied by a series of changes in color termed polychromatism. For most species, adult males and females have different color, the females usually displaying drab tones of green, brown or gray, and the males a vivid, neon color. In the Mediterranean parrotfish (Sparisoma cretense), it is the females that have neon color with the males being a drab gray.

In most species, the juveniles have a different color pattern than the adults and some tropical species this juvenile coloration can be altered temporarily to mimic the appearance of other species. As the juveniles mature they enter what is termed the initial phase coloration during which they may change color and gender. For most species, initial phase fish are usually males that have the beginnings of the adult male coloration. However, initial phase fishes may include generally mature females. The many varieties of color the parrot fish has presented to us are all part of the many phases the parrot fish goes through.

Parrotfish sleeping in a nook on a rock wall.

Feeding parrot fish of most tropical species form large schools grouped by size. Fights of several females presided over by a single male are the normal in most species, the males vigorously defending their position at any challenge. If the dominant male of a school is removed, one of the females will change gender and adopt the dominant male role.

Parrot fish are pelagic spawners; that is, they release many tiny buoyant eggs into the water which become part of the plankton. The eggs float freely, settling into the coral until hatching.

Economic importance

A commercial fishery exists for some of the larger tropical species. Their meat is rarely consumed in the US; however, it is considered a delicacy in many other parts of the world.

Protecting parrot fish is proposed as a way of saving Caribbean coral reefs from being overgrown with seaweed.^[3]

Mucus

A number of parrotfish species, including the Queen parrotfish (Scarus vetuala) excrete two different mucus types during day and night.^[4] Prior to going to sleep each night, the parrotfish extrudes mucus from its mouth, forming a protective cocoon that envelopes and secures the fish at a particular location and hides its scent from any predators.^[5][6] It also acts as an early warning detection system, allowing the parrotfish to flee, when it detects its protective membrane is disturbed by predators, such as a moray eel.^[6] The mucus also has antioxidant properties to repair any bodily damage^[4][6] and to repel any parasites, which when produced during the day, provides added protection for the parrotfish from UV light.^[4]

References

External links

Wikimedia Commons has media related to: Scaridae

• Parrot Fish Profile from National Geographic
• Parrot Fish Care
• Parrotfish info on Fishbase