ChaetodontidaeButterflyfishes

Diversity

Chaetodontidae, or butterflyfishes, are among the most widely recognized coral reef fishes. Their vivid coloration and striking patterns make them popular in the aquarium trade, although some species are difficult to maintain in aquaria (see Economic Importance). The family contains 10 genera with 114 species, the majority in the genus Chaetodon. They occur mainly in tropical waters, most densely distributed in the Indo-West Pacific, but some occupy warm temperate waters (see Habitat). Members of this family vary considerably in terms of color, but all butterflyfishes share certain morphological traits such as a deep, laterally compressed body, ctenoid scales that extend onto the soft-rayed portions of the dorsal and anal fins, and jaws that may be slightly or extremely elongated (see Physical Description). Jaw shape and size correlates with the type of prey consumed; some butterflyfishes feed upon small invertebrates or algae, others solely on coral polyps (known as obligate corallivores), and still others upon zooplankton (see Food Habits). Butterflyfish are largely pair-forming, pelagic (in the water column) spawners (see Reproduction), and are unique among reef fishes in that the larvae pass through a stage termed tholychthys during which a bony sheath encases the head (see Development). As of 1994, five chaetodontid species were listed as vulnerable to extinction (see Conservation Status). (Bellwood and Wainwright, 2002; Helfman, et al., 1997; Johnson and Gill, 2002; Kuiter, 1993; Moyle and Cech, 2000; Nelson, 1994; The World Conservation Union, 2002; Thresher, 1984)

Geographic Range

Butterflyfishes are primarily tropical, although some species can be found in temperate regions. Most species occur in the Indo- West Pacific, from Australia to Taiwan. Only four species occur in the eastern Pacific, and 13 species in the Atlantic. (Helfman, et al., 1997; Johnson and Gill, 2002; Kuiter, 1993; Nelson, 1994)

Habitat

Butterflyfishes are a marine family occupying tropical to warm temperate waters. Some occur in the brackish water of estuaries and protected bays, commonly along steep parts of rocky reefs. They are most often found in shallow (less than 20 m) water near coral reefs, but some are deepwater dwellers descending to 200 m. Some occur in seagrass habitats, deep mudflats, or shallow lagoons. Juveniles of many species occupy different areas than adults, such as tidal pools, boulder reefs and shallow areas without coral. Some investigators hypothesize that butterflyfishes may have originally been pelagic, non-reef fishes that colonized coral reefs on two or more separate occasions. (Bellwood and Wainwright, 2002; Kuiter, 1993; Nelson, 1994; Thresher, 1984)

Physical Description

Butterflyfishes are brightly-colored, often yellow or white, with darker contrasting markings that may conceal the eye. They, like some other reef fishes, are sometimes described as “poster-colored” due to their vivid coloration. They typically have a false eye spot near the back of the body, which may be an anti-predator adaptation (see Predation). These fishes are laterally compressed (very thin when viewed from the front) but deep-bodied, appearing almost circular from the side. Strongly sheathed dorsal, pelvic, and anal fin spines accentuate the disk-like body shape. The continuous or slightly notched dorsal fin contains six to 16 spines and 15 to 30 soft rays. The caudal fin is rounded and has 15 branched rays. The body is covered with small ctenoid scales that extend well onto the dorsal and anal fins. Butterflyfishes have small mouths filled with brushlike, close-set teeth. Their snouts are pointed, with the degree of elongation depending on the species and the type of food it consumes. Some, such as Forcipiger flavissimus, have extremely long jaws like tweezers that can grasp invertebrates from narrow crevices. Others, such as Chaetodon ornatissimus, have short jaws for nipping off live coral polyps. The jaws of some butterflyfishes can measure more than 25% of their body length. Butterflyfishes are, in general, sexually monomorphic (males and females look alike), although occasionally males have been found to be larger than females. Depending on the species, butterflyfishes range from nine to 30 cm in length. (Click here to see a fish diagram). (Helfman, et al., 1997; Johnson and Gill, 2002; Kuiter, 1993; Moyle and Cech, 2000; Nelson, 1994; Thresher, 1984)

  • Sexual Dimorphism
  • sexes alike

Development

Butterflyfish eggs are spherical, buoyant, and transparent, and, for those species observed, hatch in 28 to 30 hours. A drop of oil behind the yolk suspends the newly-hatched fish upside down just beneath the surface. By the time an individual reaches 5.5 mm, it enters the tholichthys larval stage, unique among reef fishes, in which bony armor covers the head. The sheath of thin bony plates extends beyond the head to form spines dorsally and ventrally. The shape and form of the plates and spines varies from species to species, but in general tholichthys larvae are silver-colored, deep bodied, and laterally compressed. These pelagic larvae may be planktonic for two or more months. The bony plates are absorbed within a few weeks after the fish settle to the bottom. The larvae settle at night and transform quickly into juveniles. In many species of butterflyfish, juveniles have a color pattern that is quite distinct from their adult form. Butterflyfishes most likely reach sexual maturity when they are about a year old. (Johnson and Gill, 2002; Kuiter, 1993; Thresher, 1984)

Reproduction

Butterflyfishes, according to existing research, are characteristically monogamous and pair-forming. Occasionally pairs have been observed accompanied by a juvenile, which allows for the possibility that juveniles may be ambisexual, or able to mature into male or female depending on which sexually mature fish in a pair dies and needs to be replaced. However, there is no definitive research indicating whether this actually occurs or not. In many species pairs are stable for at least three years, and some butterflyfishes may pair for life. (Thresher, 1984)

Research on butterflyfish reproductive behavior has been limited to a few species, but available information suggests that tropical spawning activity peaks in winter and early spring, while species in more temperate areas spawn in midsummer. Some groups spawn throughout the year. Spawning usually occurs at dusk. Females are often visibly distended with eggs when they are ready to spawn. The male swims behind and below the female, and here he uses his snout to nudge her abdomen. Spawning pairs in Prognathodes aculeatus have been observed chasing each other around a large sponge. A common element among species seems to be an ascent into the water column to release gametes (eggs and sperm). After a few “false starts” the pair rises up into the water, the male’s snout against the female’s abdomen. They release a white cloud of gametes and rush back toward the bottom. In some species other males have been seen dashing over to a spawning pair to add their own sperm to the cloud. (Thresher, 1984)

No specific information on parental care in Chaetodontidae was found. However, it is unlikely that butterflyfishes care for their eggs or young, because eggs are released and fertilized in the water column 10 or 15 m above the fishes’ normal habitat, and the pelagic tholichthys larvae are well-equipped with their own protective armor. (Thresher, 1984)

  • Parental Investment
  • no parental involvement

Lifespan/Longevity

No specific information was found on butterflyfish longevity, but it can be surmised that most species live at least three years and probably longer, since they reach sexual maturity after about a year and many pairs are reported to be stable for at least three years. (Thresher, 1984)

Behavior

Butterflyfishes are usually seen in stable heterosexual pairs, although some species move in schools or foraging groups. Sometimes a single species will school in one geographic region, and only occur in pairs elsewhere. Juveniles are typically solitary, and some act as cleaner fishes. Butterflyfishes are active during the day and move conspicuously around the reef. (Helfman, et al., 1997; Johnson and Gill, 2002; Kuiter, 1993; Moyle and Cech, 2000; Thresher, 1984)

Communication and Perception

Daytime feeders, butterflyfishes use vision to find their prey. Pairs also communicate visually; if a pair becomes separated, one may swim upwards in a display that helps the two locate each other. During agonistic encounters between members of Chaetodon lunula, the fishes’ yellow colors intensify and their countershading fades, a visual signal of aggressive interaction. (Helfman, et al., 1997; Moyle and Cech, 2000)

  • Communication Channels
  • visual

Food Habits

Generally benthic feeders, many butterflyfishes eat small invertebrates, sponges or polychaete worms. Some feed on zooplankton, and others exist exclusively on coral polyps. Another feeding method is scraping the surface of live coral to obtain algae, attached invertebrates, and mucus from the coral. Some are herbivores, grazing on the filamentous algae covering coral reefs, and a few eat seagrasses and algae on reef flats. Butterflyfishes have long snouts, with the degree of elongation depending on the species and the type of food it consumes. Some, such as Forcipiger flavissimus, have extremely long jaws like tweezers that can grasp invertebrates from narrow crevices. Others, such as Chaetodon ornatissimus, have short jaws for nipping off live coral polyps. The jaws of some butterflyfishes can measure more than 25% of their body length. (Helfman, et al., 1997; Johnson and Gill, 2002; Kuiter, 1993; Moyle and Cech, 2000; Nelson, 1994; Thresher, 1984)

Predation

Most butterflyfishes have a dark band obscuring the eye, and often have a false eye spot in contrasting colors near the tail. These two attributes may confuse predators. The ocelli, or eye spots, may reduce damage from fin-biting predators by mimicking the head. Another possibility is that the ocelli are a signal to help maintain cohesion in shoaling groups. (Helfman, et al., 1997; Johnson and Gill, 2002)

Ecosystem Roles

Butterflyfishes, like many other reef fishes, have coevolved with other organisms in their environment. Benthic invertebrates on the reef have developed heavy armor, spines, toxins, and adherence to the substrate, and butterflyfishes have evolved a variety of jaw forms that allow them to penetrate narrow crevices, reach exposed parts of invertebrates, or nip off coral polyps. The herbivorous members of the family have an impact as well, for their grazing of algae is important for the well-being of the reef. They, and other herbivorous reef fishes, keep algae that might otherwise smother the coral cropped to a mat one to two mm thick. (Moyle and Cech, 2000)

Economic Importance for Humans: Positive

Butterflyfishes are one of the most popular tropical fishes with divers and aquarists. Some do well in aquaria but those that eat only coral are almost impossible to keep successfully. (Kuiter, 1993; Thresher, 1984)

Economic Importance for Humans: Negative

No specific information was found concerning any negative impacts to humans.

Conservation Status

As of 1994 there were five species of butterflyfish listed as vulnerable to extinction, all in the genus Chaetodon. Their vulnerability is based on the limited spaces in which they are found, making them extremely susceptible to human activities in those areas. (The World Conservation Union, 2002)

  • IUCN Red List [Link]
    Not Evaluated

Other Comments

The fossil record for butterflyfishes dates back to the lower Tertiary and lower Eocene. (Berg, 1958)

Contributors

Monica Weinheimer (author), Animal Diversity Web.

R. Jamil Jonna (author), Animal Diversity Web.

Glossary

Australian

Living in Australia, New Zealand, Tasmania, New Guinea and associated islands.

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Ethiopian

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

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Neotropical

living in the southern part of the New World. In other words, Central and South America.

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Palearctic

living in the northern part of the Old World. In otherwords, Europe and Asia and northern Africa.

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benthic

Referring to an animal that lives on or near the bottom of a body of water. Also an aquatic biome consisting of the ocean bottom below the pelagic and coastal zones. Bottom habitats in the very deepest oceans (below 9000 m) are sometimes referred to as the abyssal zone. see also oceanic vent.

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

coastal

the nearshore aquatic habitats near a coast, or shoreline.

diurnal
  1. active during the day, 2. lasting for one day.
ectothermic

animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature

estuarine

an area where a freshwater river meets the ocean and tidal influences result in fluctuations in salinity.

external fertilization

fertilization takes place outside the female's body

fertilization

union of egg and spermatozoan

herbivore

An animal that eats mainly plants or parts of plants.

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).

monogamous

Having one mate at a time.

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.

oceanic islands

islands that are not part of continental shelf areas, they are not, and have never been, connected to a continental land mass, most typically these are volcanic islands.

omnivore

an animal that mainly eats all kinds of things, including plants and animals

oriental

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

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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.

planktivore

an animal that mainly eats plankton

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

social

associates with others of its species; forms social groups.

tactile

uses touch to communicate

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

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

year-round breeding

breeding takes place throughout the year

References

Bellwood, D., P. Wainwright. 2002. The History and Biogeography of Fishes on Coral Reefs. Pp. 25 in P Sale, ed. Coral Reef Fishes: Dynamics and Diversity in a Complex Ecosystem. San Diego, CA: Academic Press.

Berg, L. 1958. System Der Rezenten und Fossilen Fischartigen und Fische. Berlin: VEB Deutscher Verlag der Wissenschaften.

Helfman, G., B. Collete, D. Facey. 1997. The Diversity of Fishes. Malden, MA: Blackwell.

Johnson, G., A. Gill. 2002. Perches and Their Allies. Pp. 184 in W Eschmeyer, J Paxton, eds. Encyclopedia of Fishes – second edition. San Diego, CA: Academic Press.

Kuiter, R. 1993. Coastal Fishes of South-Eastern Australia. Honolulu, HI: University of Hawaii Press.

Moyle, P., J. Cech. 2000. Fishes: An introduction to ichthyology – fourth edition. Upper Saddle River, NJ: Prentice-Hall.

Nelson, J. 1994. Fishes of the World – third edition. New York, NY: John Wiley and Sons.

The World Conservation Union, 2002. "IUCN 2002" (On-line). 2002 IUCN Red List of Threatened Species. Accessed October 01, 2003 at http://www.iucnredlist.org/.

Thresher, R. 1984. Reproduction in reef fishes. Neptune City, NJ: T.F.H. Publications.