Yellow tangs, Zebrasoma flavescens, are reef fish found in the waters west of Hawaii and east of Japan in the Pacific Ocean. They mainly live off the coast of Hawaii, but are also found in the more western ranges of their habitat, including the islands Ryukyu, Mariana, Marshall, Marcus, and Wake. They prefer subtropical waters. (Agbayani, 2008; Waikïkï Aquarium, 1999)
Yellow tangs are reef-associated fish. Their preferred water temperature is around 21 degrees Celsius. They inhabit coral reefs in subtropical waters, but generally do not live in tropical seas. Yellow tangs mainly live in the sub-surge zone of a coral reef, this is the area with the least wave action. Zebrasoma flavescens live at depths of 2 to 46 meters. The clear larva of yellow tangs develop into marine plankton, in this stage they are carried close to reefs where they settle in coral crevices. (Agbayani, 2008; Ogawa and Brown, 2001; Reynolds and Casterlin, 1980; Waikïkï Aquarium, 1999)
Yellow tangs have a clear larval stage before developing into juveniles. Juveniles and adults have a narrow, oval body. They have an average length-weight ratio between 2.93 and 3.16. They have a long snout for eating algae, a large dorsal fin with four to five spines, and an anal fin with three spines. Like other surgeonfish and tangs (Acanthuridae), yellow tangs have a white, scalpel-like spine on both sides of the tail that can be used for defense or aggression. Yellow tangs are named for their bright yellow coloring; the only area that is not yellow is the white spine. At night, this bright yellow color changes to a darker, grayer yellow with a white lateral line. (Agbayani, 2008; Froese, 1998; Guiasu and Winterbottom, 1998; Waikïkï Aquarium, 1999; Wood, 2008)
Yellow tangs begin their lives as fertilized eggs floating in open water. After hatching, the clear, pelagic larvae develop in the plankton. They enter the acronurus larva stage where they develop an oval body, dorsal and ventral fins, and spines. After about ten weeks, they enter a planktonic stage. Here, waves carry them to a coral reef where they take refuge and continue to develop and grow. (Brough and Brough, 2008; Sale, et al., 1984; Waikïkï Aquarium, 1999; Wood, 2008)
Zebrasoma flavescens can spawn in groups or in pairs. When in groups, females release eggs and males release sperm into open water where fertilization occurs. When in pairs, the male courts a female by changing colors and exhibiting a shimmering movement. The two fish then swim upward and simultaneously release their eggs or sperm into the water. Males may spawn with multiple females in one session, while females typically spawn only once a month. (Brough and Brough, 2008; Waikïkï Aquarium, 1999; Wood, 2008)
Yellow tangs reproduce externally. Their spawning peaks from March to September, but some fish spawn at all times throughout the year. An average female can release about 40,000 eggs. (Agbayani, 2008; Detroit Zoological Society, 2008; Lobel, 1989)
There is no parental investment in yellow tangs beyond the fertilization of eggs.
Juvenile yellow tangs are often territorial. This trait usually diminishes as the fish mature and start to roam wider areas of the reef. Adult tangs live singly or in small, loose groups. These groups sometimes contain other species of fish, like sailfin tang (Zebrasoma veliferum). Yellow tangs are diurnal. During the day, tangs move from place to place, grazing on algae; at night, they generally rest alone in coral reef crevices. (Agbayani, 2008; Atkins, 1981; Brough and Brough, 2008; Wood, 2008)
When they are juveniles, yellow tangs have small home ranges that they defend, often staying within a few meters of one area. Not much is known about the home ranges of adult yellow tangs. (Parrish and Claisse, 2005)
When mating, males change colors and exhibit a shimmering movement to attract females. In defense or aggression, yellow tangs extend their fins to full length, greatly increasing their size. They also expose their scalpel-like scales on their fins as a warning sign. They use these not only to defend themselves from predators, but also to scare away competitors for food or territory. (Brough and Brough, 2008; Waikïkï Aquarium, 1999)
Yellow tangs have a long, down-turned mouth with small teeth that are specialized for grazing on algae. Because they are mainly herbivores, they spend a large amount of their time grazing either alone or in groups. A large portion of their diet consists of uncalcified and filamentous algae that grows on coral reefs. In addition to smaller types of algae, yellow tangs feed on macroalgae, such as seaweed. Yellow tangs will also eat some types of zooplankton. (Guiasu and Winterbottom, 1998; Waikïkï Aquarium, 1999; Wylie and Paul, 1988)
Predators of Zebrasoma flavescens include larger fish and predatory invertebrates such as crabs and octopi. Yellow tangs rely on camouflage and their scalpel-like fins to protect themselves. To humans, these fish appear bright yellow, but, to other fish, yellow tangs blend in very well with coral reef backgrounds. According to Marshall et al. (2003) wavelength differences between yellow and average reef color become negligible at the depths where yellow tangs are found. In addition to camouflage, Zebrasoma flavescens use their scalpel-like fins for defense. (Barry and Hawryshyn, 1999; Detroit Zoological Society, 2008; Marshall, et al., 2003; Waikïkï Aquarium, 1999)
Yellow tangs, along with other algae feeders, are crucial parts of coral reef ecosystems. They feed on algae and seaweed that grow on the reefs, preventing them from overgrowing and killing corals. Yellow tangs are also a food source for larger fish and invertebrates. (Detroit Zoological Society, 2008; Waikïkï Aquarium, 1999)
Yellow tangs are important for tourism and the aquarium trade. Their bright yellow color is well recognized by scuba divers and other tourists on Hawaiian reefs. They are also a valuable resource in aquarium trade; they are the number one collected fish for export out of Hawaii. Their coloring, hardiness, and low cost all attribute to their popularity in marine aquariums, making them one of the ten most popular fish. (Brough and Brough, 2008; Ogawa and Brown, 2001; Waikïkï Aquarium, 1999)
Yellow tangs, along with other surgeonfish (Acanthuridae), are not generally dangerous. When they are young, they possess venom glands. As they age into juveniles and adults, they lose these glands. If yellow tangs are provoked, they can inflict deep injuries with the sharp blades on their tails. (Agbayani, 2008; Waikïkï Aquarium, 1999)
Zebrasoma flavescens is not a threatened or endangered species.
Tanya Dewey (editor), Animal Diversity Web.
Kara Zabetakis (author), University of Maryland, Baltimore County, Kevin Omland (editor, instructor), University of Maryland, Baltimore County.
body of water between the southern ocean (above 60 degrees south latitude), Australia, Asia, and the western hemisphere. This is the world's largest ocean, covering about 28% of the world's surface.
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.
uses smells or other chemicals to communicate
having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.
humans benefit economically by promoting tourism that focuses on the appreciation of natural areas or animals. Ecotourism implies that there are existing programs that profit from the appreciation of natural areas or animals.
animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature
fertilization takes place outside the female's body
union of egg and spermatozoan
An animal that eats mainly plants or parts of plants.
having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.
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).
seaweed. Algae that are large and photosynthetic.
A large change in the shape or structure of an animal that happens as the animal grows. In insects, "incomplete metamorphosis" is when young animals are similar to adults and change gradually into the adult form, and "complete metamorphosis" is when there is a profound change between larval and adult forms. Butterflies have complete metamorphosis, grasshoppers have incomplete metamorphosis.
having the capacity to move from one place to another.
specialized for swimming
the area in which the animal is naturally found, the region in which it is endemic.
reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.
the business of buying and selling animals for people to keep in their homes as pets.
the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.
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.
mainly lives in oceans, seas, or other bodies of salt water.
breeding is confined to a particular season
remains in the same area
reproduction that includes combining the genetic contribution of two individuals, a male and a female
associates with others of its species; forms social groups.
uses touch to communicate
defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement
the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.
an animal which has an organ capable of injecting a poisonous substance into a wound (for example, scorpions, jellyfish, and rattlesnakes).
uses sight to communicate
breeding takes place throughout the year
animal constituent of plankton; mainly small crustaceans and fish larvae. (Compare to phytoplankton.)
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Reynolds, W., M. Casterlin. 1980. Thermoregulatory behavior of a tropical reef fish, Zebrasoma flavescens. OIKOS, 34: 356-358.
Sale, P., W. Douglas, P. Doherty. 1984. Choice of Microhabitats by Coral Reef Fishes at Settlement. Coral Reefs, 3: 91-99.
Waikïkï Aquarium, 1999. "Marine Life Profile: Yellow Tang" (On-line pdf). Waikïkï Aquarium Educational Department. Accessed April 07, 2008 at http://www.waquarium.org/MLP/root/pdf/MarineLife/Vertebrates/YellowTang.pdf.
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Wylie, C., V. Paul. 1988. Feeding preferences of the surgeonfish Zebrasoma flavescens in relation to chemical defenses of tropical algae. Marine Ecology, 45: 23-32.