PUFFERFISHES, TRIGGERFISHES, AND RELATIVES: Tetraodontiformes

PHYSICAL CHARACTERISTICS

Pufferfishes, triggerfishes, and their relatives have teeth that are fused together. If present, the pelvic fins, the pair that corresponds to the rear legs of four-footed animals, are only spines on the belly. Other than that, these fishes are amazingly different from one another. The body shape ranges from long and thick to tall and narrow. The colors range from bright to dull and from solid to wild patterns. Some of these fishes have rounded foreheads and beaks, and others have a tubelike snout. Some of these fishes have body armor, some have spines covering their bodies, some produce poison, and some can blow themselves up like a balloon.

GEOGRAPHIC RANGE

Pufferfishes, triggerfishes, and their relatives live all over the world.

HABITAT

Most pufferfishes, triggerfishes, and their relatives live in the sea, but at least twenty species live in freshwater. Some of these fishes are bottom dwellers in deep and others in shallow water. Some of these fishes live in open water, and others enter estuaries (EHS-chew-air-eez), or the areas where rivers meet the sea. Some live on coral or rocky reefs. Most freshwater species are bottom dwellers.

DIET

Pufferfishes, triggerfishes, and their relatives eat plankton, algae, and invertebrates (in-VER-teh-brehts), or animals without backbones. Plankton is microscopic plants and animals drifting in water. Algae (AL-jee) are plantlike growths that live in water and have no true roots, stems, or leaves.

BEHAVIOR AND REPRODUCTION

To defend themselves, pufferfishes, triggerfishes, and their relatives use their body armor, ability to inflate, and ability to produce poison. The color patterns show attackers that these fishes are poisonous and help the fishes hide themselves in seaweed or coral. Some of these fishes live alone and are aggressive in defending their territory. Others gather in groups of hundreds in open water to look for food. Some species form mating pairs that patrol a home territory. Scientists know little about the reproduction of pufferfishes, triggerfishes, and their relatives. Some release eggs that sink to the bottom, and others release eggs that drift in open water. Some lay eggs in nests on the bottom and guard them. The eggs of most of these fishes hatch into free-floating larvae (LAR-vee), or the early stage that must change form before becoming adults.

PUFFERFISHES, TRIGGERFISHES, THEIR RELATIVES, AND PEOPLE

Many pufferfishes, triggerfishes, and their relatives are eaten by the people who live near where the fish live. Some of these fishes are caught for sport. Some are caught and sold for food but must be prepared very carefully because they are poisonous. Many species are collected for aquariums.

CONSERVATION STATUS

The World Conservation Union (IUCN) lists three species of pufferfishes, triggerfishes, and their relatives as Vulnerable, or facing a high risk of extinction in the wild.

CLOWN TRIGGERFISH (Balistoides conspicillum): SPECIES ACCOUNTS

Physical characteristics: Clown triggerfish have an oval body that is narrow from side to side. The pelvic fins are fused into a single spine. There are three spines in the front dorsal fin. The second spine is the trigger for locking the first spine into an upright position. Clown triggerfish grow to a length of about 20 inches (50 centimeters). The bright color pattern of clown triggerfish gives the fish their name. The black background is covered by large white ovals on the bottom half and yellow rings on the upper half of the fish. The breast is white, and there is a white band below the eyes. The tail is white, and there is a pattern of black, white, black on the tail fin. Starting at the tip, the mouth colors are a wide band of yellow or orangish yellow, a narrow band of black, and a thin yellow stripe. The bases of the anal fin and the rear dorsal fin are light yellow. The anal (AY-nuhl) fin is the one along the midline of the belly. The dorsal (DOOR-suhl) fin is the one along the midline of the back. The pectoral (PECK-ter-uhl) fins correspond to the front legs and the pelvic fins to the rear legs of four-footed animals.

Geographic range: Clown triggerfish live in the Indian Ocean and the western part of the Pacific Ocean.

Habitat: Clown triggerfish live mainly on reefs.

Diet: Clown triggerfish eat bottom-dwelling invertebrates.

Behavior and reproduction: Clown triggerfish use their locking first dorsal spine as a defense against predators (PREH-duh-ters), or animals that hunt and kill other animals for food. These fish live alone and aggressively defend their territory. They spawn in pairs, laying eggs in a nest on the bottom and defending it. The larvae drift in the water.

Clown triggerfish and people: Clown triggerfish are used in aquariums.

Conservation status: Clown triggerfish are not threatened or endangered. ∎

WHITE-SPOTTED PUFFER (Arothron hispidus): SPECIES ACCOUNTS

Physical characteristics: White-spotted puffers have a long thick body. Except for the snout and tail, the body is covered with small spines. The teeth are fused to one another. The dorsal and anal fins are short. The tail fin is rounded. Two fleshy tentacles emerge from each nostril. The color is greenish brown with small white spots on the back, sides, and tail fin. The belly has white bars. White-spotted puffers grow to a length of about 20 inches (50 centimeters).

Geographic range: White-spotted puffers live in the Indian Ocean and on both sides of the Pacific Ocean.

Habitat: White-spotted puffers live on reefs.

Diet: White-spotted puffers eat algae, waste material, and invertebrates.

Behavior and reproduction: To protect themselves from predators, white-spotted puffers rapidly fill themselves up like a water balloon. These fish live alone and are territorial. They may bury themselves partially in the sand. Scientists know little about how white-spotted puffers reproduce. The fish probably lay eggs on the bottom. The larvae drift in open water.

White-spotted puffers and people: White-spotted puffers are collected for aquariums.

Conservation status: White-spotted puffers are not threatened or endangered. ∎

SPOTTED TOBY (Canthigaster solandri): SPECIES ACCOUNTS

Physical characteristics: Spotted tobies have a thick oval body, a long snout, prickles on the belly, and a rounded tail fin. They are orangish red with blue spots. The belly is white. There is a black spot ringed in pale blue directly below the base of the dorsal fin. The dorsal fin is short and white with a black base. The anal fin also is short. The skin contains a poison. Spotted tobies grow to a length of about 4 inches (10 centimeters).

Geographic range: Spotted tobies live in the western parts of the Indian and Pacific oceans.

Habitat: Spotted tobies live mainly in reefs.

Diet: Spotted tobies eat invertebrates and algae.

Behavior and reproduction: To protect themselves from predators, spotted tobies rapidly fill themselves up like a water balloon. They usually pair up but also live alone or in groups. They swim over a home range looking for food. They also swim up into open water. Pairs of spotted tobies lay eggs on algae growing on dead coral and rocks. The eggs are poisonous, and the fish do not take care of them. The larvae float in open water.

Spotted tobies and people: Spotted tobies are collected for aquariums.

Conservation status: Spotted tobies are not threatened or endangered. ∎

FOR MORE INFORMATION

Books:

Allen, Missy, and Michel Peissel. Dangerous Water Creatures. New York: Chelsea House, 1992.

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

Niesen, Thomas M. The Marine Biology Coloring Book. 2nd ed. New York: HarperResource, 2000.

Ricciuti, Edward R. Fish. Woodbridge, CT: Blackbirch, 1993.

Web sites:

"Marine Life Profile: Clown Triggerfish." Waikiki Aquarium Education Department. http://waquarium.mic.hawaii.edu/MLP/root/pdf/MarineLife/Vertebrates/ClownTriggerfish.pdf (accessed on November 9, 2004).

"Pufferfish." All Science Fair Projects. http://www.all-science-fair-projects.com/science_fair_projects_encyclopedia/Pufferfish (accessed on November 9, 2004).

"Pufferfish Found to Contain Saxitoxin." Neuroscience for Kids.http://faculty.washington.edu/chudler/puffer.html (accessed on November 9, 2004).