Parrotfish (named because their mouths resemble a parrot's beak) are a clade of fish placed in the subfamily Scarinae of the wrasse family (Labridae). Historically considered as the family Scaridae, genetic studies found them to be deeply nested within the wrasses, and they are now treated as a subfamily.
Some authorities have preferred to maintain the parrotfishes as a family-level taxon, resulting in Labridae not being monophyletic (unless split into several families).
Some sources retain the Scaridae as a family, placing it alongside the wrasses of the family Labridae and the weed whitings Odacidae in the order Labriformes, part of the Percomorpha. They also do not support the division of the Scaridae into two subfamilies. However, such a placement is paraphyletic as they are consistently recovered close to the wrasse of the subfamily Cheilininae, so they are retained with the wrasses by Eschmeyer's Catalog of Fishes. which is distinct from other fish, including other labrids; their numerous teeth are arranged in a tightly packed mosaic on the external surface of their jaw bones, forming a parrot-like beak with which they rasp algae from coral and other rocky substrates The smallest species is the bluelip parrotfish (Cryptotomus roseus), which has a maximum size of .
Protective mucus
thumb|[[Scarus zelindae in its mucus cocoon|left]]
Some parrotfish species, such as the queen parrotfish (Scarus vetula), secrete a mucus cocoon, particularly at night; prior to resting, some species extrude mucus from their mouths, forming a protective cocoon that envelops the fish, presumably hiding its scent from potential predators. A wide range of other small organisms are sometimes eaten, including invertebrates (sessile and benthic species, as well as zooplankton), bacteria and detritus. A few mostly larger species such as the green humphead parrotfish (Bolbometopon muricatum) feed extensively on living coral (polyps). After they digest the edible portions from the rock, they excrete it as sand, helping create small islands and the sandy beaches. The humphead parrotfish can produce of sand each year. An indirect effect of parrotfish grazing on sponges is the protection of reef-building corals that would otherwise be overgrown by fast-growing sponge species.
Analysis of parrotfish feeding biology describes three functional groups: excavators, scrapers and browsers. leaving visible scars on the surface.
Microscopy and molecular barcoding of coral reef substrate bitten by scraping and excavating parrotfish suggest that coral reef cyanobacteria from the order Nostocales are important in the feeding of these parrotfish. Additional microscopy and molecular barcoding research indicates that some parrotfish may ingest microscopic biota associated with endolithic sponges.
While feeding, parrotfish must be cognizant of predation, such as by the lemon shark.
Life cycle
thumb|Terminal phase [[rusty parrotfish (Scarus ferrugineus) fighting.]]
Most tropical species form large schools when feeding and these are often grouped by size. Harems are typical of most species, with the males vigorously defending their group of females and position from any challenge. As pelagic spawners, parrotfish release many tiny, buoyant eggs into the water, which become part of the plankton. The eggs float freely, settling into the coral until hatching.
Sex change
The development of parrotfishes is complex and accompanied by a series of changes in sex and colour (polychromatism), with most species being sequential hermaphrodites, starting as females (known as the initial phase) and then changing to males (the terminal phase). In many species, for example the stoplight parrotfish (Sparisoma viride), a number of individuals develop directly to males (i.e., they do not start as females). These directly developing males usually most resemble the initial phase, and often display a different mating strategy than the terminal phase males of the same species. A few species such as the Mediterranean parrotfish (S. cretense) are secondary gonochorists. This means that some females do not change sex (they remain females throughout their lives), the ones that do change from female to male do it while still immature (reproductively functioning females do not change to males) and there are no males with female-like colors (the initial phase males in other parrotfish). The marbled parrotfish (Leptoscarus vaigiensis) is the only species of parrotfish known not to change sex. In most species, juveniles have a different color pattern from adults. Juveniles of some tropical species can alter their color temporarily to mimic other species. Where the sexes and ages differ, the remarkably different phases often were first described as separate species. Despite their striking colors, their feeding behavior renders them highly unsuitable for most marine aquaria. and sponges.
Timeline of genera
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References
Further reading
- Hoey and Bonaldo. The Biology of Parrotfishes
- Monod, Th., 1979. "Scaridae". pp. 444–445. In J.C. Hureau and Th. Monod (eds.) Check-list of the fishes of the north-eastern Atlantic and of the Mediterranean (CLOFNAM). UNESCO, Paris. Vol. 1.
- Bullock, A.E. and T. Monod, 1997. "Myologie céphalique de deux poissons perroquets (Teleostei: Scaridae)". Cybium 21(2):173–199.
External links
- Parrot Fish Profile from National Geographic
- Parrot Fish Care
- Parrotfish info on Fishbase