ROUGHIES, FLASHLIGHTFISHES, AND SQUIRRELFISHES: Beryciformes

PHYSICAL CHARACTERISTICS

Roughies, flashlightfishes, and squirrelfishes are spiny-rayed fishes 3 to 24 inches (8 to 61 centimeters) long. Some have colorful scales. Squirrelfishes and soldierfishes are reddish orange from head to forked tail. Flashlightfishes have a glowing organ under each eye. Pineapplefishes and pineconefishes have large, beautiful scales. Usually yellow, each scale has its own dark outline, which makes the fish look armored. These fishes also have spines poking backward from each scale. Orange roughies have mucus cavities just beneath the skin of the head. Sometimes they are called slimeheads.

GEOGRAPHIC RANGE

Roughies, flashlightfishes, and squirrelfishes live all over the world.

HABITAT

Squirrelfishes live in shallow, tropical reefs. Roughies live in dark ocean waters 1 mile (1,600 meters) deep. The fishes that live in shallow waters usually hide under a coral overhang, in a cave, or under another structure during the day.

DIET

Roughies, flashlightfishes, and squirrelfishes eat small fish and various invertebrates (in-VER-teh-brehts), which are animals without a backbone. The shallows dwellers feed mainly at night, although some feed on invertebrates passing through their daytime retreats.

BEHAVIOR AND REPRODUCTION

Perhaps the most notable characteristic of flashlightfishes, pineapplefishes, pineconefishes, and a few other fishes in this group is their ability to produce light and in some cases control it. The light is produced by glowing bacteria that live in pockets just below the skin of the fish. These fishes use the light to find and attract prey, or animals hunted and killed for food, during their nightly feeding. Some of these fishes alter the blinking pattern of the light to communicate with other fish in their species and as a method of confusing predators (PREH-duh-ters), or animals that hunt and kill other animals for food.

Little is known about the reproduction of roughies and flashlightfishes. Scientists believe that all these fishes use external fertilization (FUR-teh-lih-zay-shun), meaning egg and sperm are united outside the body. More is known about the reproduction of squirrelfishes and soldierfishes because these fishes are common in reefs, where they are frequently observed by divers. During mating male and female squirrelfish grunt and click, align themselves side by side, and place their tails together while fanning out their heads to the left and right.

ROUGHIES, FLASHLIGHTFISHES, AND SQUIRRELFISHES AND PEOPLE

Roughies, flashlightfishes, and squirrelfishes are important in the pet business. Orange roughy is fished commercially for food.

THAT'S OLD!

Orange roughies live as long as 149 years. They are the longest-living fish.

CONSERVATION STATUS

Roughies, flashlightfishes, and squirrelfishes are not threatened or endangered.

SPLITFIN FLASHLIGHTFISH (Anomalops katoptron): SPECIES ACCOUNTS

Physical characteristics: Splitfin flashlightfish are 4 to 12 inches (10 to 30 centimeters) long. These fish have large eyes with light-producing organs below them. They have two dorsal (DOOR-suhl) fins, which are the fins along the midline of the back. The rear dorsal fin is triangular and much larger than the front one.

Geographic range: Splitfin flashlightfish live in the western part of the Pacific Ocean from the Great Barrier Reef to southern Japan.

Habitat: Splitfin flashlightfish live in reef areas 66 to 1,300 feet (20 to 400 meters) deep. During the day these fish remain hidden from sunlight, either in deep water or in dark caves. In winter, the fish gather in the warm, shallow waters of the Philippines.

Diet: Splitfin flashlightfish use their large light organ during feeding, which is done primarily at night. These fish shun even dim light, searching for food before or after the moon has risen and set or on nights of a new moon. Their diet is mainly animal plankton. Plankton are microscopic plants and animals drifting in water.

Behavior and reproduction: Splitfin flashlightfish have a light-producing organ and control it with muscles that rotate the organ either to allow the glowing bacteria to shine forth or to hide the glow from view. The fish use the light to communicate with one another. Splitfin flashlightfish often travel in schools of twenty-four to forty-eight fish. Little is known about the reproduction of these fish except that they probably do not guard eggs.

Splitfin flashlightfish and people: Splitfin flashlightfish are used in the aquarium business. Sometimes they are used for bait.

Conservation status: Splitfin flashlightfish are not threatened or endangered. ∎

BLACKBAR SOLDIERFISH (Myripristis jacobus): SPECIES ACCOUNTS

Physical characteristics: Blackbar soldierfish grow to 10 inches (25 centimeters) in length. They are red and have large eyes, two dorsal fins, and a forked tail fin. They sport a brownish black, vertical bar behind the gill cover.

Geographic range: Blackbar soldierfish live in the Gulf of Mexico and the eastern Atlantic Ocean from North Carolina to Brazil.

Habitat: Blackbar soldierfish live in reefs and around structures such as piers. They are commonly seen by divers in very shallow waters but also are found at depths to 330 feet (100 meters).

Diet: Blackbar soldierfish feed at night on shrimp and animal plankton.

Behavior and reproduction: Blackbar soldierfish usually live alone but sometimes form schools of as many as thirty-six fish. Under stress, blackbar soldierfish make clicking and grunting noises with their swim bladder, an internal sac that fishes use to control their position in the water. Blackbar soldierfish often swim upside down. These fish use external fertilization on the days that follow a full moon. Although the adults prefer shallower reefs, the larvae (LAR-vee) may travel well out to sea. Larvae are animals in an early stage and must change form before becoming adults.

Blackbar soldierfish and people: Blackbar soldierfish are used as pets. They are sometimes sold for food.

Conservation status: Blackbar soldierfish are not threatened or endangered. ∎

FOR MORE INFORMATION

Books:

Ferrari, Andrea, and Antonella Ferrari. Reef Life. Buffalo, NY: Firefly, 2002.

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

Web sites:

"Flashlightfish." Shedd Aquarium. http://www.sheddaquarium.org/sea/fact_sheets.cfm?id=99 (accessed on October 12, 2004).

"Myripristis jacobus." New Jersey State Aquarium. http://www.njaquarium.org/species/index3.php3?exhibit=2&tank=35&animal=96 (accessed on October 12, 2004).

"Orange Roughy (Hoplostethus atlanticus)." Oceans Alive. http://www.oceansalive.org/eat.cfm?subnav=fishpage&fish=70 (accessed on October 12, 2004).