''Acanthurus coeruleus'' is a

surgeonfish Acanthuridae are the family of surgeonfishes, tangs, and unicornfishes. The family includes about 86 extant species of marine fish living in tropical seas, usually around coral reefs. Many of the species are brightly colored and popular in a ...

found commonly in the

Atlantic Ocean The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about . It covers approximately 20% of Earth's surface and about 29% of its water surface area. It is known to separate the " Old World" of Africa, Europe ...

. It can grow up to long.Figueiredo, J.L. and N.A. Menezes, (2000). ''Manual de peixes marinhos do sudeste do Brasil. VI. Teleostei (5)''. Museu de Zoologia, Universidade de São Paulo. Brazil. Common names include Atlantic blue tang, blue barber, blue doctor, blue doctorfish, blue tang, blue tang surgeonfish, yellow barber, and yellow doctorfish.

Distribution

''Acanthurus coeruleus'' is present in the western Atlantic Ocean from New York to Florida, Mexico and Brazil, and Ascension Island in the Mid-Atlantic. Also found in the Mediterranean Sea since 2011.

Description

Although the body of the reef fish can vary in shade from light to dark blue, the

dorsal Dorsal (from Latin ''dorsum'' ‘back’) may refer to: * Dorsal (anatomy), an anatomical term of location referring to the back or upper side of an organism or parts of an organism * Dorsal, positioned on top of an aircraft's fuselage * Dorsal c ...

, anal and

caudal fin Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as se ...

s are golden blue. As juveniles, the edges on their dorsal and anal fins and the rings around their eyes are purple-blue, blue or blue-green. Their colors change during growth from a yellow juvenile, yellow tailed blue subadult and the blue adult phase. ''Acanthurus coeruleus'' exhibits

biofluorescence Fluorescence is the emission of light by a substance that has absorbed light or other electromagnetic radiation. It is a form of luminescence. In most cases, the emitted light has a longer wavelength, and therefore a lower photon energy, tha ...

, that is, when illuminated by blue or ultraviolet light, it re-emits it as green, and appears differently than under white light illumination (see image to the right). Biofluorescence may assist in intraspecific communication and camouflage.

Ecology

Feeding

Atlantic blue tangs inhabit coral reefs and inshore grassy and rocky areas, where there is a high prevalence of algae. They are

herbivorous A herbivore is an animal anatomically and physiologically adapted to eating plant material, for example foliage or marine algae, for the main component of its diet. As a result of their plant diet, herbivorous animals typically have mouthpar ...

, and their diet consists only of filamentous

algae Algae (; singular alga ) is an informal term for a large and diverse group of photosynthetic eukaryotic organisms. It is a polyphyletic grouping that includes species from multiple distinct clades. Included organisms range from unicellular micr ...

detritus In biology, detritus () is dead particulate organic material, as distinguished from dissolved organic material. Detritus typically includes the bodies or fragments of bodies of dead organisms, and fecal material. Detritus typically hosts comm ...

and

plankton Plankton are the diverse collection of organisms found in water (or air) that are unable to propel themselves against a current (or wind). The individual organisms constituting plankton are called plankters. In the ocean, they provide a cruc ...

. They eat the algae from the reefs in which they reside, as well as off the bodies of surrounding fish. By eating the algae off of other fish, the blue tang serve as cleaners for them. With the decline in the '' Diadema antillarum'' (

sea urchin Sea urchins () are spiny, globular echinoderms in the class Echinoidea. About 950 species of sea urchin live on the seabed of every ocean and inhabit every depth zone from the intertidal seashore down to . The spherical, hard shells (tests) o ...

) population, the blue tang population increased since the algal resources that the two animals usually competed for were more abundant. Juvenile blue tangs eat continuously and feed heavily. This heavy feeding requirement is due to their poor utilization of food resources. The blue tang's stomach and intestinal lining are proficient at absorbing crushed cellular content, but are not very effective at processing

cellulose Cellulose is an organic compound with the formula , a polysaccharide consisting of a linear chain of several hundred to many thousands of β(1→4) linked D-glucose units. Cellulose is an important structural component of the primary cell wa ...

. This digestive system inefficiency leads blue tangs to spend more time and resources on foraging on a very abundant and fast-growing food source in close proximity. This close proximity to an abundant food source allows for continuous foraging.

Food competition

Food distribution, density, and accessibility can determine population density and territory size in blue tangs. Territories with low

biogenic A biogenic substance is a product made by or of life forms. While the term originally was specific to metabolite compounds that had toxic effects on other organisms, it has developed to encompass any constituents, secretions, and metabolites of p ...

structure are larger than those of higher biogenic structure. Since the algal food resources are less dense in low-biogenic structured areas, these territories would have to be larger in order to include the necessary amount of food. This is in accordance with the

Ideal free distribution In ecology, an ideal free distribution (IFD) is a theoretical way in which a populations individuals distribute themselves among several patches of resources within their environment, in order to minimize resource competition and maximize fitness ...

model. This model states that competitors should adjust their distribution in accordance with habitat quality such that each individual will gain the same amount of resources. According to this model, there should be a lower density of blue tangs on low-biogenic structured territories compared to higher-biogenic structured territories where there is a higher abundance of food. In both territories, each individual will receive similar amounts of resources due to competition. There is no significant difference in feeding rates of blue tangs on each type of territory, meaning that those in larger, uncolonized, and low density territories can match the resources of those in smaller high density territories.

Cleaning behavior

Atlantic blue tangs engage in

cleaning Cleaning is the process of removing unwanted substances, such as dirt, infectious agents, and other impurities, from an object or environment. Cleaning is often performed for aesthetic, hygienic, functional, environmental, or safety purposes. ...

behaviors with other fish as both cleaners and clients. In these interactions, cleaners remove parasites and other materials from the surface of the client. Clients benefit by having ectoparasites and damaged tissue removed from the outside of their body. Removal of unwanted organisms and tissue can lead to improved health maintenance.

Cleaner interactions

Atlantic blue tangs act as cleaners by grazing algae as well as eating molted skin and parasites off of the client's flesh once the client comes to the cleaning station. The most common client in these interactions is the

green turtle The green sea turtle (''Chelonia mydas''), also known as the green turtle, black (sea) turtle or Pacific green turtle, is a species of large sea turtle of the family Cheloniidae. It is the only species in the genus ''Chelonia''. Its range exten ...

, in which the blue tang inspects the green turtle by nipping its head, limbs, tail, and

carapace A carapace is a dorsal (upper) section of the exoskeleton or shell in a number of animal groups, including arthropods, such as crustaceans and arachnids, as well as vertebrates, such as turtles and tortoises. In turtles and tortoises, the unde ...

Client interactions

When acting as clients, blue tangs normally approach cleaning stations inhabited by cleaner gobies. The blue tang's flippers are the most inspected area. Cleaners must be careful because the spine on both sides of the

caudal peduncle Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as see ...

are sharp and can inflict painful wounds. When in the client role, blue tangs will pose as they enter the cleaning station. Posing occurs before the cleaners inspect the incoming client fish. Fish who pose while in cleaning stations have a higher chance of getting cleaned. Blue tangs almost exclusively pose through head stands.

Wound healing

Clients who are cleaned by blue tang benefit after suffering an injury. Blue tangs incur many minor injuries, but infection as a result of injuries rarely leads to death. Recovery rates from both minor and major injuries are very high in blue tangs. Injured blue tangs are found to spend more time in cleaning stations compared to those further along in the healing process. This indicates that cleaning plays an important role in the wound healing process. Cleaners pick at the wound and eat the dead tissue in the

peripheral A peripheral or peripheral device is an auxiliary device used to put information into and get information out of a computer. The term ''peripheral device'' refers to all hardware components that are attached to a computer and are controlled by the ...

area.

Social modes

Blue tangs experience three different social modes:

territorial A territory is an area of land, sea, or space, particularly belonging or connected to a country, person, or animal. In international politics, a territory is usually either the total area from which a state may extract power resources or an ...

, schooling, and wandering. Blue tangs in non-territorial modes form schools and wander, while territorial blue tangs do not. Territoriality reduces competition for food resources because one individual claims both a territory and its resources. Additionally, schooling allows fish to better overcome food defense by others, and wandering allows for individual movement to feeding areas, cleaning stations, and other resources. Social behaviors are affected by outside conditions such as damselfish density, conspecific population density, and life history stage. Those in the territorial mode are

aggressive Aggression is overt or covert, often harmful, social interaction with the intention of inflicting damage or other harm upon another individual; although it can be channeled into creative and practical outlets for some. It may occur either reacti ...

and actively chase intruding blue tangs. They swim slower and feed more frequently than non-territorial blue tangs. Schooling fish form compact groups with other blue tangs in addition to other species. Territorial blue tangs are found most often in the reef flat zone (sandy-bottomed with rocks or coral) and are rarely found in the spur zone (low coral ridges) or groove zone (sandy bottom channels). Territoriality prevalence decreases with increasing damselfish population, and the time of day also does not affect territoriality prevalence. Fish in schooling mode swim fast, eat at intermediate rates, and are not aggressive, even though they are often chased by damselfish. Schooling is the most prevalent in areas with high damselfish densities such as the groove zone, spur zone, and crest zone (shallow reef area), while schools are most prevalent near midday. Wandering blue tangs are often chased by other fish, and also visit cleaning stations more often than those in the other modes. Wandering is found most often in the reef back zone (enclosed region with irregular patches of algae, rock and sand) and during the morning. With an increase in conspecific population density, blue tang individuals become more territorial. Small, juvenile blue tangs are territorial, but the incidence of territoriality in the larger classes decreases. However, in these fish, schooling and wandering increases.

Juvenile behavior

Juvenile blue tangs exhibit different behavior than both

conspecific Biological specificity is the tendency of a characteristic such as a behavior or a biochemical variation to occur in a particular species. Biochemist Linus Pauling stated that "Biological specificity is the set of characteristics of living organis ...

and

congeneric Congener may refer to: * A thing or person of the same kind as another, or of the same group. * Congener (biology), organisms within the same genus. * Congener (chemistry), related chemicals, e.g., elements in the same group of the periodic table. ...

adults. Juveniles are prevalent in the reef crest zone, spur zone, and on the fringe of the reef flat zone, but are rare inside of the reef flat zone. Juveniles remain solitary on their home ranges, and home range territory size increases with body size. These territories overlap with those of ''Stegastes'' damselfish. Juvenile blue tangs are aggressive in territory defense. They try to avoid ''stegastes'', and are rarely chased by these damselfish.

Relationship with humans

While not under human threat, the Atlantic blue tang is caught for

commercial fishing Commercial fishing is the activity of catching fish and other seafood for commercial profit, mostly from wild fisheries. It provides a large quantity of food to many countries around the world, but those who practice it as an industry must oft ...

, but maintains little importance to Caribbean industry. It is also used, though rarely, as bait. It is also common in the aquarium trade. The fish is of low commercial value, giving off a pungent stench.

Ciguatera Ciguatera fish poisoning (CFP), also known simply as ciguatera, is a foodborne illness caused by eating reef fish whose flesh is contaminated with certain toxins. Such individual fish are said to be ciguatoxic. Symptoms may include diarrhea, vom ...

poisoning may occur if the flesh is consumed. The adult fish's caudal spine is sharp, and is only out when the fish experiences excitement of some form. These fins can cut very deep into human skin and have been known to result in infections, mainly characterized by swelling and discoloration. Pain from such infections can last for long periods of time, sometimes for hours. Some species of the genus ''Acanthurus'' are even thought to possess poison glands on their caudal spines.

References

External links

* {{Taxonbar , from=Q882618 Acanthurus Fish of the Western Atlantic Fish of the Dominican Republic Fish of the Caribbean Fauna of Ascension Island Fish described in 1801