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Coris aygularedthroated rainbowfish

By Joshua Lehto-Jacobs

Geographic Range

Coris aygula, the clown wrasse, is found primarily near Eastern Africa and Southern Asia. More specifically, they occupy areas near Comores, Madagascar, Cargados Carajos/St. Brandon’s Shoals, Aldabra, Sychelles, Maldives, as well as from the Chagos Archipelago to the Ducie Islands. They are also found in the area up to and including Southern Japan, Ryukyu, the Bonin and Ogawawara Islands, and South to the Lord Howe and Rapa Islands.

(Fricke, 1999; Shirai, 1986)

Habitat

C. aygula is a marine reef-associated fish, inhabiting rocky reef and coral areas. It lives in depth from 2 to 30 meters. It is tropical fish requiring a temperature between 24 and 28 degrees Celsius.

(Westneat, 2002; Randall, 1990)

  • Aquatic Biomes
  • reef
  • Range depth
    2 to 30 m
    6.56 to 98.43 ft

Physical Description

C. aygula has 9 dorsal spines, between 12 and 13 dorsal soft rays, 3 anal spines, 14 pectoral rays, and 12 anal soft rays. The first two spines lie closer together than others. They also have between 59 and 67 lateral line scales. Males and females are slightly different. Males develop a hump on the forehead. The caudal fin of the famale is slightly more rounded than that of the male. Also, males have very long pelvic fins. Females have a white-colored streak in front of the anal fin. They also have light yellow or green coloring on the body with small, maroon spots and scales with dark edges, while males are blue-green in color. Onmales there are often broad, pale, green bars along the middle of the body. Juveniles have an extremely different appearance than adults. They are white and have black spots on each dorsal fin. They also have 2 circular orange/red spots on their back.

(Westneat, 2002; Shirai, 1986; Randall, 1990)

  • Range length
    120 (high) cm
    47.24 (high) in

Development

Large C. aygula males change color and form as they develop. Juveniles start out with white coloration. There are orange or red colored spots on the back. Each dorsal fin has a large black spot. They eventually become a dark-green color, with less variation in color over the body. The first dorsal spine becomes elongated and a hump on the forehead becomes apparent.

(Westneat, 2002; Randall, 1990)

Reproduction

When spawning, wrasses gather in loose aggregations where one dominant male oversees many females within a general territory. If the dominant male dies then usually the largest female will transform into the resident male.

(Thresher 1984)

C. aygula is a member of the wrasse family. Members of this family are protogynous hermaphrodites. This means that most members of the population begin life as females and some transform and function as males later. The differences between the primary males (born male) and secondary males (born female) are evident in the structure of the gonads, which are located in the upper sides of the abdominal cavity between the viscera and the coelomic wall. In primary males, the gonads are elongate, white, and solid with a small, tubular sperm duct extending posteriorly. This sperm duct extends to the urogenital opening. In secondary males, the gonads are hollow, short, thick, and yellowish because the gonads began as ovaries and later developed into testes. The secondary male testes have a large central space referred to as the lumen. The lumen has a ring of lobe-like projections around it. These are the ovarian lamellae. In females, when the eggs are ripe, they burst free from the lamellae and enter the lumen. They are then expelled through the urogenital opening.

Members of the wrasse family spawn along the outer edge of a reef patch. In more extensive reef complexes, fish will spawn along the outer slope.

(Thresher 1984)

  • Parental Investment
  • no parental involvement

Behavior

C. aygula adults are solitary except when spawning. They find and capture their prey by turning over rocks.

(Randall 1990)

Communication and Perception

C. aygula uses body coloration to signal either members of their own species or other species. This would not be possible without the extreme clarity of reef water. This subject is somewhat controversial, but the colors may be a warning signal or camouflauge against the reef.

(Lowe-McConnell 1987)

  • Communication Channels
  • visual

Food Habits

C. aygula eat shelled mollusks, hermit crabs, other crabs, and sea urchins.

(Randall 1990)

  • Animal Foods
  • mollusks
  • aquatic crustaceans

Predation

C. aygula is brightly colored, which may camoflauge it among the bright colors of its natural reef habitat.

(Lowe-McConnell 1987)

Ecosystem Roles

C. aygula is eaten by large piscivores which also eat small fish-feeders, detritus-feeders, coral-feeders, and midwater piscivores. Therefore, C. aygula helps to sustain the large piscivore population inhabiting reefs. C. aygula also help to control the populations of those reef invertebrates at lower trophic levels. In turn, they allow the species that these animals feed on to survive.

(Lowe-McConnell, 1987; Randall, 1990)

Economic Importance for Humans: Positive

C. aygula is a valuable and popular aquarium species. They are also considered to be a game fish.

(Randall, 1990, Westneat, 2002)

Conservation Status

Contributors

William Fink (editor), University of Michigan-Ann Arbor.

Joshua Lehto-Jacobs (author), University of Michigan-Ann Arbor.

Glossary

Ethiopian

living in sub-Saharan Africa (south of 30 degrees north) and Madagascar.

World Map

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

carnivore

an animal that mainly eats meat

chemical

uses smells or other chemicals to communicate

external fertilization

fertilization takes place outside the female's body

fertilization

union of egg and spermatozoan

food

A substance that provides both nutrients and energy to a living thing.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

molluscivore

eats mollusks, members of Phylum Mollusca

motile

having the capacity to move from one place to another.

natatorial

specialized for swimming

native range

the area in which the animal is naturally found, the region in which it is endemic.

oriental

found in the oriental region of the world. In other words, India and southeast Asia.

World Map

oviparous

reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

pet trade

the business of buying and selling animals for people to keep in their homes as pets.

polymorphic

"many forms." A species is polymorphic if its individuals can be divided into two or more easily recognized groups, based on structure, color, or other similar characteristics. The term only applies when the distinct groups can be found in the same area; graded or clinal variation throughout the range of a species (e.g. a north-to-south decrease in size) is not polymorphism. Polymorphic characteristics may be inherited because the differences have a genetic basis, or they may be the result of environmental influences. We do not consider sexual differences (i.e. sexual dimorphism), seasonal changes (e.g. change in fur color), or age-related changes to be polymorphic. Polymorphism in a local population can be an adaptation to prevent density-dependent predation, where predators preferentially prey on the most common morph.

protogynous

condition of hermaphroditic animals (and plants) in which the female organs and their products appear before the male organs and their products

reef

structure produced by the calcium carbonate skeletons of coral polyps (Class Anthozoa). Coral reefs are found in warm, shallow oceans with low nutrient availability. They form the basis for rich communities of other invertebrates, plants, fish, and protists. The polyps live only on the reef surface. Because they depend on symbiotic photosynthetic algae, zooxanthellae, they cannot live where light does not penetrate.

saltwater or marine

mainly lives in oceans, seas, or other bodies of salt water.

seasonal breeding

breeding is confined to a particular season

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

solitary

lives alone

tactile

uses touch to communicate

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

visual

uses sight to communicate

References

Fricke, R. 1999. Fishes of the Macarene Islands (Reunion, Mauritius, Rodriguez). Koenigstein: Koeltz Scientific Books.

Lowe-McConnell, R. 1987. Ecological Studies in Tropical Fish Communities. Cambridge: Cambridge University Press.

Randall, J. 1990. Fishes of the Great Barrier Reef and Coral Sea. Australia: Crawford House Publishing Pty, Ltd..

Shirai, S. 1986. The Marine Animals of the Indo-Pacific. Japan: Shin Nippon Tosho Co., Ltd..

Thresher, R. 1984. Reproduction in Reef Fishes. Neptune City, New Jersey: TFH Publications Inc, Ltd..

Westneat, M. "Coris Aygula Species Summary" (On-line). Accessed November 11, 2002 at http://www.fishbase.org/Summary/SpeciesSummary.cfm?ID=5624%0d%0a%09%09%09%09%09&genusname=Coris%0d%0a%09%09%09%09%09&speciesname=aygula.

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