SURGEONFISHES AND RELATIVES: Acanthuroidei

PHYSICAL CHARACTERISTICS

Surgeonfishes and their relatives have small to medium-sized bodies that are narrow from side to side and may be disk-like, oval, or slightly long. Many of these fishes have sharp venomous spines or ridges. Many of these fishes are very colorful.

GEOGRAPHIC RANGE

Surgeonfishes and their relatives live in the Atlantic, Indian, and Pacific oceans.

HABITAT

Most surgeonfishes and their relatives live in shallow coral and rocky reefs. Some species live in estuaries (EHS-chew-air-eez), or the areas where rivers meet the sea, or even farther upstream into freshwater. One species lives in the open sea.

DIET

Most surgeonfishes and their relatives eat bottom-dwelling algae and invertebrates (in-VER-teh-brehts), or animals without backbones. Algae (AL-jee) are plantlike growths that live in water and have no true roots, stems, or leaves. Some species of these fishes can crush shells. One species eats mostly plants, and one species eats jellylike plankton, which is microscopic plants and animals drifting in water.

BEHAVIOR AND REPRODUCTION

Surgeonfishes and their relatives live alone, in pairs, in small groups, in schools of their own species, or in mixed-species schools. Many of these fishes defend their territories. Surgeonfishes and their relatives spawn, or release eggs, in pairs or in groups. Most of these fishes release free-floating eggs. One species deposits eggs on the bottom and takes care of them. The larvae of many surgeonfishes and their relatives live for a long time in the open sea. Larvae (LAR-vee) are animals in an early stage and must change form before becoming adults.

SURGEONFISHES AND THEIR RELATIVES AND PEOPLE

Many surgeonfishes and their relatives are used in aquariums. The larger species are caught and sold for food. Other fishes are caught and eaten by people who live near where the fish live.

Did You Know?

Yellow tangs are the number one aquarium fish export from the Hawaiian Islands.

What's in a Name?

Surgeonfish are called that because their venomous spines resemble scalpels, which are the knives surgeons use to cut into their patients.

CONSERVATION STATUS

Surgeonfishes and their relatives are not threatened or endangered.

LINED SURGEONFISH (Acanthurus lineatus): SPECIES ACCOUNTS

Physical characteristics: Lined surgeonfish have a disk-like body that is narrow from side to side. There is a large, venomous spine on each side of the tail. The tail fin is shaped like a crescent moon. The body color is yellowish green with bright blue stripes that are edged with black on the sides of the fish but not on the head. The belly is bluish white. The tail fin has two up-and-down lines of dark blue against a background of purplish gray. The pelvic fins, the pair that corresponds to the rear legs of four-footed animals, are bright orange. The other fins are purplish gray at the edges and greenish yellow at the base. The dorsal and anal fins are long. The dorsal (DOOR-suhl) fin is the one along the midline of the back. The anal (AY-nuhl) fin is the one along the midline of the belly. Lined surgeonfish grow to a length of about 15 inches (38 centimeters).

Geographic range: Lined surgeonfish live in the Indian and Pacific oceans.

Habitat: Lined surgeonfish live on reefs at a depth of 3 to 10 feet (1 to 3 meters).

Diet: Lined surgeonfish eat algae.

Behavior and reproduction: Lined surgeonfish patrol their territory on reefs and aggressively attack other fishes, using their tail spines as weapons. Their head becomes a darker color during these meetings. Lined surgeonfish travel to spawn in groups at specific sites, although they sometimes spawn in pairs. Eggs and larvae float in open water. Lined surgeonfish live as long as forty-five years.

Lined surgeonfish and people: Lined surgeonfish are collected for aquariums and are caught and eaten by people who live near where the fish live.

Conservation status: Lined surgeonfish are not threatened or endangered. ∎

YELLOW TANG (Zebrasoma flavescens): SPECIES ACCOUNTS

Physical characteristics: Yellow tangs have a disk-like body that is narrow from side to side. The forehead curves in rather than out, and the snout is long. The dorsal fin sticks up high and has four to five spines. The anal fin has three spines. The body is bright yellow. Yellow tangs grow to a length of more than 8 inches (20 centimeters).

Geographic range: Yellow tangs live in the Pacific Ocean.

Habitat: Yellow tangs live in coral and rocky reefs and in bays and lagoons.

Diet: Yellow tangs eat algae.

Behavior and reproduction: Yellow tangs live in small groups or alone. The groups often move from point to point to browse on algae. These fish sometimes live in mixed-species schools. Single males may defend territories, court passing females, and spawn with them in open water. Yellow tangs also sometimes spawn in groups. Eggs and larvae float in open water.

Yellow tangs and people: Yellow tangs are used in aquariums.

Conservation status: Yellow tangs are not threatened or endangered. ∎

MOORISH IDOL (Zanclus cornutus): SPECIES ACCOUNTS

Physical characteristics: Moorish idols have a disk-like body that is narrow from side to side. The third spine in the dorsal fin is very long and whiplike. These fish have three up-and-down bands of white and yellow alternating with two bands of black. The tail fin is black and fringed with white or yellowish white. The snout has a small patch of yellow and a band of white. The snout is tubular. Adult Moorish idols grow to a length of at least 6 inches (15 centimeters).

Geographic range: Moorish idols live in the Indian and Pacific oceans.

Habitat: Moorish idols live in coral and rocky reefs and in lagoons.

Diet: Moorish idols eat bottom-dwelling invertebrates, especially sponges.

Behavior and reproduction: Moorish idols live alone, in pairs, or in small groups, but large groups may gather for spawning. Scientists know little about the reproduction of Moorish idols. These fish spawn in pairs in small or possibly large groups. Eggs and larvae float freely.

Moorish idols and people: Moorish idols are collected for aquariums but do not do well in captivity. They are eaten by people who live near where the fish live.

Conservation status: Moorish idols are not threatened or endangered. ∎

FOR MORE INFORMATION

Books:

Gilbert, Carter Rowell, and James D. Williams. National Audubon Society Field Guide to Fishes: North America. New York: Knopf, 2002.

Web sites:

"Marine Life Profile: Moorish Idol." Waikiki Aquarium Education Department. http://waquarium.mic.hawaii.edu/MLP/root/pdf/MarineLife/Vertebrates/MoorishIdol.pdf (accessed on November 4, 2004).

Wood, Lori. "The Yellow Tang." WhoZoo. http://www.whozoo.org/Anlife99/loriwood/tang3.htm (accessed on November 4, 2004).