Parrotfish
Encyclopedia
Parrotfishes are a group of fishes that traditionally had been considered a family (Scaridae), but now often are considered a subfamily (Scarinae) of the wrasse
Wrasse
The wrasses are a family, Labridae, of marine fish, many of which are brightly colored. The family is large and diverse, with over 600 species in 82 genera, which are divided into nine subgroups or tribes....

s. They are found in relatively shallow tropical and subtropical oceans throughout the world, but with the largest species richness
Species richness
Species richness is the number of different species in a given area. It is represented in equation form as S.Species richness is the fundamental unit in which to assess the homogeneity of an environment. Typically, species richness is used in conservation studies to determine the sensitivity of...

 in the Indo-Pacific
Indo-Pacific
The Indo-Pacific is a biogeographic region of the Earth's seas, comprising the tropical waters of the Indian Ocean, the western and central Pacific Ocean, and the seas connecting the two in the general area of Indonesia...

. The approximately 90 species are found in coral reef
Coral reef
Coral reefs are underwater structures made from calcium carbonate secreted by corals. Coral reefs are colonies of tiny living animals found in marine waters that contain few nutrients. Most coral reefs are built from stony corals, which in turn consist of polyps that cluster in groups. The polyps...

s, rocky coasts and seagrass
Seagrass
Seagrasses are flowering plants from one of four plant families , all in the order Alismatales , which grow in marine, fully saline environments.-Ecology:...

 beds, and play a significant role in bioerosion
Bioerosion
Bioerosion describes the erosion of hard ocean substrates – and less often terrestrial substrates – by living organisms. Marine bioerosion can be caused by mollusks, polychaete worms, phoronids, sponges, crustaceans, echinoids, and fish; it can occur on coastlines, on coral reefs, and...

.

Taxonomy

Traditionally, the parrotfish have been considered a family level taxon
Taxon
|thumb|270px|[[African elephants]] form a widely-accepted taxon, the [[genus]] LoxodontaA taxon is a group of organisms, which a taxonomist adjudges to be a unit. Usually a taxon is given a name and a rank, although neither is a requirement...

, Scaridae. Although phylogenetic and evolutionary analysis of parrotfishes is still ongoing, it is now accepted that they are a clade
Clade
A clade is a group consisting of a species and all its descendants. In the terms of biological systematics, a clade is a single "branch" on the "tree of life". The idea that such a "natural group" of organisms should be grouped together and given a taxonomic name is central to biological...

 in the tribe
Tribe (biology)
In biology, a tribe is a taxonomic rank between family and genus. It is sometimes subdivided into subtribes.Some examples include the tribes: Canini, Acalypheae, Hominini, Bombini, and Antidesmeae.-See also:* Biological classification* Rank...

 Cheilini, and are now commonly referred to as scarine labrids (subfamily Scarinae, family Labridae). Some authorities have preferred to maintain the parrotfishes as a family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...

 level taxon
Taxon
|thumb|270px|[[African elephants]] form a widely-accepted taxon, the [[genus]] LoxodontaA taxon is a group of organisms, which a taxonomist adjudges to be a unit. Usually a taxon is given a name and a rank, although neither is a requirement...

, resulting in Labridae not being monophyletic.

Characteristics

Parrotfish are named for their dentition
Dentition
Dentition pertains to the development of teeth and their arrangement in the mouth. In particular, the characteristic arrangement, kind, and number of teeth in a given species at a given age...

, which also is distinct from that of other labrids. Their numerous teeth are arranged in a tightly packed mosaic on the external surface of the jaw bones, forming a parrot
Parrot
Parrots, also known as psittacines , are birds of the roughly 372 species in 86 genera that make up the order Psittaciformes, found in most tropical and subtropical regions. The order is subdivided into three families: the Psittacidae , the Cacatuidae and the Strigopidae...

-like beak with which they rasp algae
Algae
Algae are a large and diverse group of simple, typically autotrophic organisms, ranging from unicellular to multicellular forms, such as the giant kelps that grow to 65 meters in length. They are photosynthetic like plants, and "simple" because their tissues are not organized into the many...

 from coral and other rocky substrates (which contributes to the process of bioerosion
Bioerosion
Bioerosion describes the erosion of hard ocean substrates – and less often terrestrial substrates – by living organisms. Marine bioerosion can be caused by mollusks, polychaete worms, phoronids, sponges, crustaceans, echinoids, and fish; it can occur on coastlines, on coral reefs, and...

).

Although they are considered to be herbivore
Herbivore
Herbivores are organisms that are anatomically and physiologically adapted to eat plant-based foods. Herbivory is a form of consumption in which an organism principally eats autotrophs such as plants, algae and photosynthesizing bacteria. More generally, organisms that feed on autotrophs in...

s, parrotfish eat a wide variety of reef organisms, and they are not necessarily vegetarian. Species such as the green humphead parrotfish
Green humphead parrotfish
The green humphead parrotfish, Bolbometopon muricatum, is the largest species of parrotfish growing to lengths of and weighing up to . It is found on reefs in the Indian and Pacific Oceans, from the Red Sea in the west to Samoa in the east, and from the Yaeyama Islands in the north to the Great...

 (Bolbometopon muricatum) include coral
Coral
Corals are marine animals in class Anthozoa of phylum Cnidaria typically living in compact colonies of many identical individual "polyps". The group includes the important reef builders that inhabit tropical oceans and secrete calcium carbonate to form a hard skeleton.A coral "head" is a colony of...

 (polyp
Polyp
A polyp in zoology is one of two forms found in the phylum Cnidaria, the other being the medusa. Polyps are approximately cylindrical in shape and elongated at the axis of the body...

s) in their diet. Their feeding activity is important for the production and distribution of coral sands in the reef biome
Biome
Biomes are climatically and geographically defined as similar climatic conditions on the Earth, such as communities of plants, animals, and soil organisms, and are often referred to as ecosystems. Some parts of the earth have more or less the same kind of abiotic and biotic factors spread over a...

, and can prevent algae from choking coral. The teeth grow continuously, replacing material worn away by feeding. The pharyngeal teeth
Pharyngeal teeth
Pharyngeal teeth are teeth in the pharyngeal arch of the throat of cyprinids, suckers, and a number of other fish species lacking teeth.Popular aquarium fish such as goldfish and loaches have these structures. Members of the Botia genus such as clown loaches are known to make distinctive clicking...

 grind up coral rock the fish ingest during feeding. After they digest the rock, they excrete it as sand, helping to create small islands and the sandy beaches of the Caribbean
Caribbean
The Caribbean is a crescent-shaped group of islands more than 2,000 miles long separating the Gulf of Mexico and the Caribbean Sea, to the west and south, from the Atlantic Ocean, to the east and north...

. One parrotfish can produce 90 kg of sand each year.

Maximum sizes vary within the family, with the majority of species reaching 30–50 cm (11.8–19.7 in) in length. However, a few species reach lengths in excess of 1 m, and the green humphead parrotfish can reach up to 1.3 metres (4.3 ft).

Life cycle

The development of parrotfish is complex and accompanied by a series of changes in color termed polychromatism. Almost all species are sequential hermaphrodites, starting as females (known as the initial phase) and then changing to males (the terminal phase). However, in many species, for example the stoplight parrotfish
Stoplight parrotfish
The Stoplight parrotfish is a sex-changing fish inhabiting coral reefs in Florida, Bahamas, the Caribbean, eastern Gulf of Mexico, Bermuda, and Brazil. Its typical length is between 30 and 45 cm, but it can reach 60 cm at times...

 (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, for example the Mediterranean parrotfish (S. cretense), are secondary gonochorist, meaning that some females do not change sex, and the ones that do, change from female to male while still immature (i.e., reproductively functioning females do not change to males). The marbled parrotfish
Marbled parrotfish
The marbled parrotfish or seagrass parrotfish is a species of parrotfish, the only member of the genus Leptoscarus. It is found in coastal regions with seagrass, ranging from the Red Sea in west to Easter Island in east, and Japan in north to New Zealand and South Africa in south...

 (Leptoscarus vaigiensis) is the only species of parrotfish known not to change sex. In most species, the initial phase is dull red, brown or grey, while the terminal phase is vividly green or blue with bright pink or yellow patches. The remarkably different terminal and initial phases were first described as separate species in several cases, but there are also some species where the phases are similar.

In most parrotfish species, juveniles have a different color pattern from adults. Juveniles of some tropical species can alter their color temporarily to mimic other species.
Feeding parrotfish of most tropical species form large schools grouped by size. Fights of several females presided over by a single male are normal in most species, the males vigorously defending their position from any challenge.

Parrotfish are pelagic spawners; they release many tiny buoyant eggs into the water, which become part of the plankton
Plankton
Plankton are any drifting organisms that inhabit the pelagic zone of oceans, seas, or bodies of fresh water. That is, plankton are defined by their ecological niche rather than phylogenetic or taxonomic classification...

. The eggs float freely, settling into the coral until hatching.

Economic importance

A commercial fishery
Fishery
Generally, a fishery is an entity engaged in raising or harvesting fish which is determined by some authority to be a fishery. According to the FAO, a fishery is typically defined in terms of the "people involved, species or type of fish, area of water or seabed, method of fishing, class of boats,...

 exists for some of the larger tropical species, particularly in the Indo-Pacific.

Protecting parrotfish is proposed as a way of saving Caribbean coral reefs from being overgrown with seaweed.

Despite their striking colors, their feeding behavior renders them highly unsuitable for most marine aquaria
Aquarium
An aquarium is a vivarium consisting of at least one transparent side in which water-dwelling plants or animals are kept. Fishkeepers use aquaria to keep fish, invertebrates, amphibians, marine mammals, turtles, and aquatic plants...

.

Mucus

A number of parrotfish species, including the queen parrotfish
Queen parrotfish
The queen parrotfish is a species of parrotfish found at reefs in the Caribbean Sea.-References:* Yahoo! Kids. * Beautiful Oceans....

 (Scarus vetula), secrete a mucus cocoon, particularly at night. 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. This mucous envelope may also act as an early warning system, allowing the parrotfish to flee when it detects predators such as moray eel
Moray eel
Moray eels are cosmopolitan eels of the family Muraenidae. The approximately 200 species in 15 genera are almost exclusively marine, but several species are regularly seen in brackish water and a few, for example the freshwater moray can sometimes be found in freshwater...

s disturbing the protective membrane. The skin itself is covered in another mucous substance that may have antioxidant properties that may serve to repair bodily damage, or serve to repel parasites, in addition to providing protection from UV light
Ultraviolet
Ultraviolet light is electromagnetic radiation with a wavelength shorter than that of visible light, but longer than X-rays, in the range 10 nm to 400 nm, and energies from 3 eV to 124 eV...

.

External links

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