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| Parrotfish | ||||||||||
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Bolbometopon Calotomus Cetoscarus Chlorurus Cryptotomus Hipposcarus Leptoscarus Nicholsina Scarus Sparisoma |
Parrotfish are strictly tropical, perciform marine fish of the family Scaridae. Found on the shallow reefs of the Atlantic, Indian and Pacific Oceans, the parrotfish family contains nine genera and approximately 60-83 species.
Parrotfish are named for their unusual dentition: their teeth are fused into a parrot-like beak which the animals use to rasp algae from coral. Many species are also brightly coloured in shades of blue, green, red and yellow, but are not especially popular in aquaria due to their destructive mode of feeding. Although herbivores, parrotfish can lethally damage coral through feeding. However, they are an important producer of coral sands in the reef biome and prevent algae from choking coral. Their beak-like teeth grow continuously, making it hard to curb overgrowth in the aquarium. Ingested during feeding, coral is ground up by the molar-like teeth in the throat. It assists in digestion and is later excreted with the fish's other wastes as coral sand.
Maximum sizes vary widely within the family, from 30 centimetres long in the smaller of the species to 1.3 metres long in the largest species, the green humphead parrotfish (Bolbometopon muricatum) which may weigh up to 46 kilograms. A commercial fishery exists for the larger species. Their bodies are deep, with large, thick cycloid scales, small eyes, large pectoral fins and homocercal tail fins. The pectorals are the parrotfish's primary means of locomotion, the tail only used when speed is required.
Parrotfish are diurnal and stay within shallow waters of no more than about 70 metres in depth. By night they cram themselves into crevices, some species secreting a thick coat of mucus as a sort of sleeping bag. The mucus masks their scent from nocturnal predators such as sharks and fends off parasites.
The development of parrotfish can be confusing: males and females are both a drab grey as juveniles—known as the initial phase—with the former developing vivid, conspicuous colours as they mature. However, females will commonly change sex as they enter maturity—known as the terminal phase—and will adopt male coloration. Males of some species (such as the bumpheads) will also develop rounded, projecting foreheads. The strong sexual dimorphism of parrotfish has led to the sexes of many species to be erroneously classed as different species in the past. Coloration is highly variable even among members of the same species. This "identity crisis" is shared by their close relatives, the wrasses of the family Labridae.
Known by some as the "cows of the sea," grazing parrotfish of some species will form large schools grouped by size. Harems of several females presided over by a single male are the norm in other species, the males vigorously defending their status at any challenge. Parrotfish 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 substrate until hatching.