Scarus

Scarus is most closely related to its sister genus Chlorurus. Most recent phylogenetic analyses find that the two genera diverged during the late Miocene (Messinian).^[1] In both genera, most of their diversification occurred some time later, within the last 3.5 million years during the Pliocene.^[5] In contrast, coral reefs in their modern form were established much earlier, during the Miocene.^[1]

Most Scarus species occur in reef habitats. Because some species such as S. zufar occur in rockier, more peripheral habitats, patterns of phylogenetic relationships have led researchers to suggest that these habitats may be the ancestral habitat type for the genus.^[1]

A 2012 phylogenetic analysis of 45 Scarus species recovered 10 major monophyletic clades.^[1]

Adults of most species reach maximum lengths of between 30 and 50 cm (12–20 in), but the rainbow parrotfish (Scarus guacamaia) can grow to lengths of 1.2 m (3.9 ft)^[3] and is the second largest species of parrotfish after the humphead parrotfish.^[6] S. guacamaia weighs a hundred times more than the smallest Scarus species Scarus iseri,^[1] which only reaches a maximum length of 27 cm.^[7]

In comparison to its sister genus Chlorurus, Scarus species in general have less obtuse head profiles, less extensive cheek areas, and smaller dental plates, although a few species of Scarus are exceptions to this. This may possibly reflect comparatively lower biting power, and a disparity in the ability to excavate calcareous reef subtrata.^[1]

Scarus species are important herbivores in reef ecosystems, feeding predominantly on algae and dead coral.^[10] In the process, they facilitate bioerosion and create sediment.^[11]

Lifespan varies across different species. More short-lived species, such as the common parrotfish (S. psittacus), live for up to 6 years.^[7] Other species are more long-lived; the endangered greenback parrotfish (S. trispinosus) has been recorded living for over 20 years, and is the largest herbivorous reef fish in the South Atlantic.^[11] Its close relative, the midnight parrotfish (S. coelestinus),^[1] has been recorded reaching 31 years of age.^[7] Such large bodied and long-lived species are highly vulnerable to over-exploitation by fisheries.^[11]

Many species within the genus are sympatric with each other, and often are sympatric with their sister species; Scarus frequently underwent sympatric speciation through adaptive radiation.^[1]

There are currently 52 recognised species in this genus:^[3]

More information Species, Common name ...

Species	Common name	Initial phase	Terminal phase
Scarus altipinnis (Steindachner, 1879)	filament-finned parrotfish
Scarus arabicus (Steindachner, 1902)	Arabian parrotfish
Scarus caudofasciatus (Günther, 1862)	red-barred parrotfish
Scarus chameleon Choat & Randall, 1986	chameleon parrotfish
Scarus chinensis (Steindachner, 1867)
Scarus coelestinus Valenciennes, 1840	midnight parrotfish
Scarus coeruleus (Edwards, 1771)	blue parrotfish
Scarus collana Rüppell, 1835	Red Sea parrotfish
Scarus compressus (Osburn & Nichols 1916)	azure parrotfish
Scarus dimidiatus Bleeker, 1859	yellow-barred parrotfish
Scarus dubius (E. T. Bennett, 1828)	regal parrotfish
Scarus falcipinnis (Playfair, 1868)	sicklefin parrotfish
Scarus ferrugineus Forsskål, 1775	rusty parrotfish
Scarus festivus Valenciennes, 1840	festive parrotfish
Scarus flavipectoralis Schultz, 1958	yellowfin parrotfish
Scarus forsteni (Bleeker, 1861)	Forsten's parrotfish
Scarus frenatus Lacépède, 1802	bridled parrotfish
Scarus fuscocaudalis Randall & Myers, 2000	darktail parrotfish
Scarus fuscopurpureus (Klunzinger, 1871)	purple-brown parrotfish
Scarus ghobban Forsskål, 1775	blue-barred parrotfish
Scarus globiceps Valenciennes, 1840	globehead parrotfish
Scarus gracilis (Steindachner 1869)
Scarus guacamaia Cuvier, 1829	rainbow parrotfish
Scarus hoefleri (Steindachner, 1881)	Guinean parrotfish
Scarus hypselopterus Bleeker, 1853	yellowtail parrotfish
Scarus iseri (Bloch, 1789)	striped parrotfish
Scarus koputea Randall & Choat, 1980	Marquesan parrotfish
Scarus longipinnis Randall & Choat, 1980	highfin parrotfish
Scarus maculipinna Westneat, Satapoomin & Randall, 2007	spot-fin parrotfish
Scarus niger Forsskål, 1775	dusky parrotfish
Scarus obishime Randall & Earle, 1993	yellowtail parrotfish
Scarus oviceps Valenciennes, 1840	dark-capped parrotfish
Scarus ovifrons Temminck & Schlegel, 1846	knobsnout parrotfish
Scarus perrico Jordan & Gilbert, 1882	bumphead parrotfish
Scarus persicus Randall & Bruce, 1983	gulf parrotfish
Scarus prasiognathos Valenciennes, 1840	Singapore parrotfish
Scarus psittacus Forsskål 1775	common parrotfish
Scarus quoyi Valenciennes, 1840	Quoy's parrotfish
Scarus rivulatus Valenciennes, 1840	rivulated parrotfish
Scarus rubroviolaceus Bleeker, 1847	ember parrotfish
Scarus russelii Valenciennes, 1840	eclipse parrotfish
Scarus scaber Valenciennes, 1840	fivesaddle parrotfish
Scarus schlegeli Bleeker, 1867	yellowband parrotfish
Scarus spinus (Kner)	greensnout parrotfish
Scarus taeniopterus Lesson, 1829	princess parrotfish
Scarus tricolor Bleeker, 1847	tricolour parrotfish
Scarus trispinosus Valenciennes, 1840	greenback parrotfish
Scarus vetula Bloch & Schneider, 1801	queen parrotfish
Scarus viridifucatus J.L.B. Smith, 1956	roundhead parrotfish
Scarus xanthopleura Bleeker, 1853	red parrotfish
Scarus zelindae Moura, Figueiredo & Sazima, 2001	Zelinda's parrotfish
Scarus zufar Randall & Hoover, 1995	Dhofar parrotfish

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In Cesare Ripa's Renaissance iconography, the scarus fish symbolised civil "Union," i.e. the joining of individuals into a collective body. Plutarch had written that scarus fish "swim together in shoals and ingeniously and heroically free each other when caught in a net." The scarus thus "denoted reciprocal assistance in the fight for survival."^[12]