Scarus is a genus of parrotfishes. With 52 currently recognised extant species,Froese, R. and D. Pauly, Eds. Scarus. FishBase. 2013. it is by far the largest parrotfish genus. The vast majority are found at reefs in the Indo-Pacific, but a small number of species are found in the warmer parts of the eastern Pacific and the western Atlantic, with a single species, Scarus hoefleri in the eastern Atlantic.
The genus name Scarus comes from the Greek word σκάρος (skáros), which refers to parrotfishes.
Evolution 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). In both genera, most of their diversification occurred some time later, within the last 3.5 million years during the Pliocene. In contrast, coral reefs in their modern form were established much earlier, during the Miocene.
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.
A 2012 phylogenetic analysis of 45 Scarus species recovered 10 major monophyletic clades.
With over 50 species, Scarus is the largest of the parrotfish genera, and the only genus to be present in all tropical and subtropical oceans.
Description Adults of most species reach maximum lengths of between , but the rainbow parrotfish (Scarus guacamaia) can grow to lengths of and is the second largest species of parrotfish after the humphead parrotfish. S. guacamaia weighs a hundred times more than the smallest Scarus species Scarus iseri, which only reaches a maximum length of 27 cm.
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.
The number of pectoral rays, which varies from 13 to 16 between Scarus species, is useful for identifying species, as well as the number of predorsal scales and the number of rows of scales on the cheek. However, most other meristic data is of limited use when identifying species of Scarus: dorsal rays, anal rays, and lateral line scales do not vary much in number between parrotfish species, and there is high intra-specific variation in gill raker count.
Sexual dichromatism Most Scarus species are very colourful, and most are sexually dichromatic, with strikingly different initial (male and female) and terminal (male only) phases. However in a few species, initial phase and terminal phase colouration remains the same. Examples of such sexually monochromatic species include S. guacamaia, S. coelestinus, S. perrico, S. niger, and S. coeruleus.
Ecology
Scarus species are important herbivores in reef ecosystems, feeding predominantly on algae and dead coral. In the process, they facilitate bioerosion and create sediment.
Lifespan varies across different species. More short-lived species, such as the common parrotfish (S. psittacus), live for up to 6 years. 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. Its close relative, the midnight parrotfish (S. coelestinus), has been recorded reaching 31 years of age. Such large bodied and long-lived species are highly vulnerable to over-exploitation by fisheries.
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.
Species There are currently 52 recognised species in this genus: +SpeciesCommon nameInitial phaseTerminal phaseScarus altipinnis (Steindachner, 1879)filament-finned parrotfishScarus arabicus (Steindachner, 1902)Arabian parrotfishScarus caudofasciatus (Günther, 1862)red-barred parrotfishScarus chameleon Choat & Randall, 1986chameleon parrotfishScarus chinensis (Steindachner, 1867)Scarus coelestinus Valenciennes, 1840midnight parrotfishScarus coeruleus (Edwards, 1771)blue parrotfishScarus collana Rüppell, 1835Red Sea parrotfishScarus compressus (Osburn & Nichols 1916)azure parrotfishScarus dimidiatus Bleeker, 1859yellow-barred parrotfishScarus dubius (E. T. Bennett, 1828)regal parrotfishScarus falcipinnis (Playfair, 1868)sicklefin parrotfishScarus ferrugineus Forsskål, 1775rusty parrotfishScarus festivus Valenciennes, 1840festive parrotfishScarus flavipectoralis Schultz, 1958yellowfin parrotfishScarus forsteni (Bleeker, 1861)Forsten's parrotfishScarus frenatus Lacépède, 1802bridled parrotfishScarus fuscocaudalis Randall & Myers, 2000darktail parrotfishScarus fuscopurpureus (Klunzinger, 1871)purple-brown parrotfishScarus ghobban Forsskål, 1775blue-barred parrotfishScarus globiceps Valenciennes, 1840globehead parrotfishScarus gracilis (Steindachner 1869)Scarus guacamaia Cuvier, 1829rainbow parrotfishScarus hoefleri (Steindachner, 1881)Guinean parrotfishScarus hypselopterus Bleeker, 1853yellowtail parrotfishScarus iseri (Bloch, 1789)striped parrotfishScarus koputea Randall & Choat, 1980Marquesan parrotfishScarus longipinnis Randall & Choat, 1980highfin parrotfishScarus maculipinna Westneat, Satapoomin & Randall, 2007spot-fin parrotfishScarus niger Forsskål, 1775dusky parrotfishScarus obishime Randall & Earle, 1993yellowtail parrotfishScarus oviceps Valenciennes, 1840dark-capped parrotfishScarus ovifrons Temminck & Schlegel, 1846knobsnout parrotfishScarus perrico Jordan & Gilbert, 1882bumphead parrotfishScarus persicus Randall & Bruce, 1983gulf parrotfishScarus prasiognathos Valenciennes, 1840Singapore parrotfishScarus psittacus Forsskål 1775common parrotfishframelessScarus quoyi Valenciennes, 1840Quoy's parrotfishScarus rivulatus Valenciennes, 1840rivulated parrotfishScarus rubroviolaceus Bleeker, 1847ember parrotfishScarus russelii Valenciennes, 1840eclipse parrotfishScarus scaber Valenciennes, 1840fivesaddle parrotfishScarus schlegeli Bleeker, 1867yellowband parrotfishScarus spinus (Kner)greensnout parrotfishScarus taeniopterus Lesson, 1829princess parrotfishScarus tricolor Bleeker, 1847tricolour parrotfishScarus trispinosus Valenciennes, 1840greenback parrotfishScarus vetula Bloch & Schneider, 1801queen parrotfishScarus viridifucatus J. L. B. Smith, 1956roundhead parrotfishScarus xanthopleura Bleeker, 1853red parrotfishScarus zelindae Moura, Figueiredo & Sazima, 2001Zelinda's parrotfishScarus zufar Randall & Hoover, 1995Dhofar parrotfish
In political thought 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."Hont, I. Jealousy of Trade: International Competition and the Nation-State in Historical Perspective. Harvard UP: 2005, pp. 21-22.
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