Parrotfish | |
---|---|
Scarus frenatus | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Actinopterygii |
Order: | Labriformes |
Family: | Scaridae Rafinesque, 1810 |
Genera | |
Bolbometopon Contents |
Parrotfish are a group of fish species traditionally regarded as a family (Scaridae), but now often treated as a subfamily (Scarinae) or tribe (Scarini) of the wrasses (Labridae). [1] With roughly 95 species, this group's largest species richness is in the Indo-Pacific. They are found in coral reefs, rocky coasts, and seagrass beds, and can play a significant role in bioerosion. [2] [3] [4]
Parrotfish are named for their dentition, [5] 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 [6] (which contributes to the process of bioerosion).
Maximum sizes vary within the group, with the majority of species reaching 30–50 cm (12–20 in) in length. However, a few species reach lengths in excess of 1 m (3 ft 3 in), and the green humphead parrotfish can reach up to 1.3 m (4 ft 3 in). [7] The smallest species is the bluelip parrotfish (Cryptotomus roseus), which has a maximum size of 13 cm (5.1 in). [8] [9] [10]
Some parrotfish species, including the queen parrotfish (Scarus vetula), secrete a mucus cocoon, particularly at night. [11] Prior to going to sleep, some species extrude mucus from their mouths, forming a protective cocoon that envelops the fish, presumably hiding its scent from potential predators. [12] [13] This mucus envelope may also act as an early warning system, allowing the parrotfish to flee when it detects predators such as moray eels disturbing the membrane. [13] The skin itself is covered in another mucous substance which may have antioxidant properties helpful in repairing bodily damage, [11] [13] or repelling parasites, in addition to providing protection from UV light. [11]
Most parrotfish species are herbivores, feeding mainly on epilithic algae. [14] [15] [16] A wide range of other small organisms are sometimes eaten, including invertebrates (sessile and benthic species, as well as zooplankton), bacteria and detritus. [17] A few mostly larger species such as the green humphead parrotfish (Bolbometopon muricatum) feed extensively on living coral (polyps). [6] [15] [16] None of these are exclusive corallivores, but polyps can make up as much as half their diet [16] or even more in the green humphead parrotfish. [14] Overall it has been estimated that fewer than one percent of parrotfish bites involve live corals and all except the green humphead parrotfish prefer algae-covered surfaces over live corals. [16] Nevertheless, when they do eat coral polyps, localized coral death can occur. [16] Their feeding activity is important for the production and distribution of coral sands in the reef biome, and can prevent algal overgrowth of the reef structure. The teeth grow continuously, replacing material worn away by feeding. [9] Whether they feed on coral, rock or seagrasses, the substrate is ground up between the pharyngeal teeth. [16] [18] 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 90 kg (200 lb) of sand each year. [19] Or, on average (as there are so many variables i.e. size/species/location/depth etc.), almost 250 g (9 oz) per parrotfish per day. While feeding, parrotfish must be cognizant of predation by one of their main predators, the lemon shark. [20] On Caribbean coral reefs, parrotfish are important consumers of sponges. [21] 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. [22] [23]
Analysis of parrotfish feeding biology describes three functional groups: excavators, scrapers and browsers. [14] Excavators have larger, stronger jaws that can gouge the substrate, [24] leaving visible scars on the surface. [14] Scrapers have less powerful jaws that can but infrequently do leave visible scraping scars on the substrate. [14] [24] Some of these may also feed on sand instead of hard surfaces. [14] Browsers mainly feed on seagrasses and their epiphytes. [14] Mature excavating species include Bolbometopon muricatum , Cetoscarus , Chlorurus and Sparisoma viride . [14] These excavating species all feed as scrapers in early juvenile stages, but Hipposcarus and Scarus , which also feed as scrapers in early juvenile stages, retain the scraping feeding mode as adults. [14] [24] Browsing species are found in the genera Calotomus , Cryptotomus , Leptoscarus , Nicholsina and Sparisoma. [14] Feeding modes reflect habitat preferences, with browsers chiefly living in the grassy seabed, and excavators and scrapers on coral reefs. [25] [14]
Recently, the microphage feeding hypothesis challenged the prevailing paradigm of parrotfish as algal consumers by proposing that:
Most parrotfishes are microphages that target cyanobacteria and other protein-rich autotrophic microorganisms that live on (epilithic) or within (endolithic) calcareous substrata, are epiphytic on algae or seagrasses, or endosymbiotic within sessile invertebrates. [26]
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. [27] Additional microscopy and molecular barcoding research indicates that some parrotfish may ingest microscopic biota associated with endolithic sponges. [28]
The development of parrotfishes is complex and accompanied by a series of changes in sex and colour (polychromatism). Most species are 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. [29] 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). [30] [31] [32] The marbled parrotfish (Leptoscarus vaigiensis) is the only species of parrotfish known not to change sex. [9] In most species, the initial phase is dull red, brown, or grey, while the terminal phase is vividly green or blue with bright pink, orange or yellow patches. [9] [33] In a smaller number of species the phases are similar, [9] [33] and in the Mediterranean parrotfish the adult female is brightly colored, while the adult male is gray. [34] 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. [35] Where the sexes and ages differ, the remarkably different phases often were first described as separate species. [33] As a consequence early scientists recognized more than 350 parrotfish species, which is almost four times the actual number. [29]
Most tropical species form large schools when feeding and these are often grouped by size. Harems of several females presided over by a single male are normal in most species, with the males vigorously defending their 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.
The sex change in parrotfishes is accompanied by changes in circulating steroids. Females have high levels of estradiol, moderate levels of T and undetectable levels of the major fish androgen 11-ketotestosterone. During the transition from initial to terminal coloration phases, concentrations of 11-ketotestosterone rise dramatically and estrogen levels decline. If a female is injected with 11-ketotestosterone, it will cause a precocious change in gonadal, gametic and behavioural sex.[ citation needed ]
A commercial fishery exists for some of the larger species, particularly in the Indo-Pacific, [9] but also for a few others like the Mediterranean parrotfish. [36] Protecting parrotfishes is proposed as a way of saving Caribbean coral reefs from being overgrown with seaweed [37] and sponges. [22] [23] Despite their striking colors, their feeding behavior renders them highly unsuitable for most marine aquaria. [9]
A new study has discovered that the parrotfish is extremely important for the health of the Great Barrier Reef; it is the only one of thousands of reef fish species that regularly performs the task of scraping and cleaning inshore coral reefs. [38]
Traditionally, the parrotfishes have been considered to be a family level taxon, Scaridae. Although phylogenetic and evolutionary analyses of parrotfishes are ongoing, they are now accepted to be a clade in the tribe Cheilini, and are now commonly referred to as scarine labrids (subfamily Scarinae, family Labridae). [1] Some authorities have preferred to maintain the parrotfishes as a family-level taxon, [33] resulting in Labridae not being monophyletic (unless split into several families).
The World Register of Marine Species divides the group into two subfamilies as follows:
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. [39]
The green humphead parrotfish is the largest species of parrotfish, growing to lengths of 1.5 m (4.9 ft) and weighing up to 75 kg (165 lb).
Sparisoma is a genus of parrotfishes native to warmer parts of the Atlantic. FishBase recognizes 15 species in this genus, including S. rocha described from Trindade Island in 2010 and S. choati described from the East Atlantic in 2012. They are the most important grazers of algae in the Caribbean Sea, especially since sea urchins, especially Diadema, the other prominent consumers of algae, have been reduced in many places by a recent epidemic.
The princess parrotfish is a species of marine ray-finned fish, a parrotfish, in the family Scaridae. It is typically 20 to 25 centimetres long, found in the Caribbean, South Florida, the Bahamas, and Bermuda. Its behavior, similar to other parrotfishes, is to swim about the reef and sandy patches during the day, at depths between 3 and 25 metres, scraping algae on which it feeds.
The stoplight parrotfish is a species of marine ray-finned fish, a parrotfish from the family Scaridae, inhabiting coral reefs in Florida, Caribbean Sea, Gulf of Mexico, Bermuda and as far south as Brazil. It mainly feeds on algae by scraping and excavating it with its teeth. Like most of its relatives, it is able to change sex.
Cetoscarus bicolor, also known as the bicolour parrotfish or bumphead parrotfish, is a species of fish belonging to the family Scaridae. It is found only in the Red Sea. Being from the Scaridae family of huge, vividly colored fish, which is well known as a main contributor of marine ecosystems, especially coral reefs by maintaining them.
The rusty parrotfish is a species of marine ray-finned fish, a parrotfish belonging to the family Scaridae. It is associated with reefs in the north western Indian Ocean and the Red Sea.
The queen parrotfish is a species of marine ray-finned fish, a parrotfish, in the family Scaridae. It is found on reefs in the tropical West Atlantic Ocean and the Caribbean Sea. Other common names include blownose, blue chub, blue parrotfish, blueman, joblin crow parrot, moontail, okra peji and slimy head. The young males and adult female queen parrotfish are a reddish-brown color, and quite different in appearance from the bluish-green color of the final phase male. This is a common species throughout its range and the International Union for Conservation of Nature has rated its conservation status as "least concern".
The blue parrotfish is a member of the parrotfish genus Scarus. It is found on coral reefs in shallow water in the tropical and subtropical parts of the western Atlantic Ocean and the Caribbean Sea. They usually forage in a group of 500 individuals for spawning and deterring predators while feeding.
Chlorurus bleekeri, known commonly as Bleeker's parrotfish, is a species of marine fish in the family Scaridae.
Chlorurus sordidus, known commonly as the daisy parrotfish or bullethead parrotfish, is a species of marine fish in the family Scaridae.
Scarus niger, common names the swarthy parrotfish, dusky parrotfish, and black parrotfish, is a species of parrotfish. It is in the phylum Chordata, class Actinopterygii, and family Scaridae. Like other members of its family, it has characteristic 10 dorsal soft rays, 9 dorsal spines, 9 anal soft rays, and 3 anal spines, It is found in Indo-West and Central Pacific, from the Red Sea, north to Japan, south to Australia and east to French Polynesia. It is found in lagoons, channels and outer reefs slopes on the depths of 2 to 20 metres. The dusky parrotfish often lives in solitude, but males may also live in a small group of mating females. The dusky parrotfish is primarily herbivorous, and its main source of food is benthic algae. At maturity, the fish is approximately 230-240mm long and weighs around 240g.
Hipposcarus harid, the Longnose parrotfish or Candelamoa parrotfish, is a species of marine ray-finned fish, a parrotfish from the family Scaridae found on coral reefs of Indian Ocean and the Red Sea.
Scarus ghobban, also known as the blue-barred parrotfish, blue trim parrotfish, cream parrotfish, globe-headed parrotfish, green blotched parrotfish, yellow scale parrotfish, and bluechin parrotfish, is a species of marine ray-finned fish in the family Scaridae.
Chlorurus microrhinos, the blunt-head parrotfish or steephead parrotfish, is a species of marine ray-finned fish, a parrotfish from the family Scaridae. It is found in the Indo-Pacific region.
Chlorurus spilurus, known commonly as the Pacific daisy parrotfish or Pacific bullethead parrotfish and in Hawaiian called uhu, is a species of marine fish in the family Scaridae. The Pacific daisy parrotfish is widespread throughout the tropical waters of the Pacific.
Scarus fuscopurpureus, common name purple-brown parrotfish, is a species of marine ray-finned fish, belonging to the class Actinopterygii. It is a parrotfish in the family Scaridae. It occurs in the western Indian Ocean, the Red Sea, the gulf of Aden and the Persian Gulf. Countries in which boarder these waters include, but are not limited to Egypt, Sudan, Saudi Arabia, Yemen, Kuwait, and the United Arab Emirates.
Chlorurus gibbus, the heavybeak parrotfish, gibbus parrotfish or Red Sea steephead parrotfish, is a species of marine ray-finned fish, a parrotfish from the family Scaridae. It is found in the Red Sea.
Scarus psittacus, the common parrotfish, is a species of marine ray-finned fish, a parrotfish, in the family Scaridae. Other common names for this species include the palenose parrotfish, Batavian parrotfish and the rosy-cheek parrotfish. It has a wide distribution in the Indo-Pacific region where it is associated with coral reefs. This species is utilised as food. It is the type species of the genus Scarus.
Sparisoma choati, the West-African parrotfish, is a species of marine ray-finned fish from the family Scaridae. It occurs at depths between 2 and 30m, along west African coastline and islands from Cape Verde and Senegal south to the offshore islands of the Gulf of Guinea and northern Angola. Like other parrotfish of the genus Sparisoma, it lives on rocky reefs and grazes on algae growing over hard substrate. It was named in honor of J. Howard Choat, in recognition of his extensive scientific work on parrotfishes.
Scarus zelindae is a species of fish of the Scaridae family in the order Perciformes. This species of Parrotfish can be brown, blue, green, yellow, and purple and can change their colors several times throughout their lifetime. They live for about 5–7 years and can be found in the southwestern Atlantic Ocean, primarily in Brazilian waters.
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