HAGFISHES: Myxini

PHYSICAL CHARACTERISTICS

Hagfishes look like eels and are about 18–30 inches (46–76 centimeters) long. The skeleton is made up of cartilage (KAR-teh-lej), or tough, bendable tissue, rather than bone. Hagfishes have no fins or scales—flat, rigid plates that act as body covering. They do not have jaws but have two raspy, or rough, biting plates. The mouth is an oval slit surrounded by four barbels (BAR-buhls), which are long, thin feelers used for finding food. The single nostril is surrounded by another set of barbels. The eyes are two dents on the top of the head that are covered by skin, and the fishes probably cannot see with them. Hagfishes have six to ten pairs of gills, or breathing organs, which may open directly to the outside or join to form one gill opening. The color of hagfishes ranges from reddish brown to grayish pink. Hagfishes have about 100 to 150 slime glands along the sides of their bodies.

GEOGRAPHIC RANGE

Hagfishes live in the Atlantic, Pacific, Indian, Arctic, and Antarctic Oceans and in the Bering, Mediterranean, and Caribbean Seas.

HABITAT

Most hagfishes live at the bottom of the ocean. Atlantic hagfishes live on soft, muddy bottoms, where they form burrows. Pacific hagfishes live on surfaces ranging from soft, muddy bottoms to boulders and sand, where they coil up and nestle among rocks.

DIET

Hagfishes eat dead and dying fish, small worms, and crustaceans (krus-TAY-shuns), which are animals that live in water and have a soft, segmented body covered by a hard shell, such as hermit crabs and shrimps. Using its biting plate, a hagfish pierces the food animal and bores into it, eating the soft insides and leaving only the bones and skin or shell.

BEHAVIOR AND REPRODUCTION

Hagfishes live in large groups on the ocean floor. They defend themselves by producing slime. Their reproductive patterns are unknown. Fertilization (FUR-teh-lih-zay-shun), or the joining of sperm and eggs to begin development, is probably external, or outside the body. Male reproductive cells are called sperm and female's are called eggs. The fishes release eggs and sperm into the water, and eggs that come into contact with sperm are fertilized. Each clutch, or group of eggs, contains twenty to thirty yolky eggs that are 0.8–1 inch (2–2.5 centimeters) long. The eggs are enclosed in a tough shell with threads at each end, which anchor the eggs in the mud.

HAGFISHES AND PEOPLE

Hagfishes help the environment by cleaning the ocean floor. They also are caught for meat and their skins. People who buy leather goods made out of "eel skin" are actually buying products made with hagfish skin.

SLIME AND KNOTS

Hagfishes make slime in glands along the sides of their bodies. When attacked or handled, the fish forms a small amount of slime, which expands to a gallon or so when it comes in contact with the surrounding water. The hagfish then slips away. The hagfish rids itself of the slime by tying itself in a knot and scraping itself clean by moving the knot down its body.

CONSERVATION STATUS

Hagfishes are not threatened with extinction.

ATLANTIC HAGFISH (Myxine glutinosa): SPECIES ACCOUNT

Physical characteristics: Atlantic hagfishes are 18–31 inches (45–78 centimeters) long and grayish or reddish brown tubes. They are jawless and have four barbels around the mouth. The nose also is surrounded by four barbels. The eyespots are on top of the head and are covered with thick skin. Atlantic hagfishes have a single pair of gill openings. There are slime glands along the sides of the body.

Geographic range: Atlantic hagfishes are found on both sides of the North Atlantic Ocean, in the Arctic Ocean, and in the seas of Europe, except for the eastern Mediterranean Sea and the Black Sea.

Habitat: Atlantic hagfishes live in deep waters of 328–984 feet (100–300 meters) on soft, muddy bottoms, in which they form burrows.

Diet: Atlantic hagfishes feed on dead and dying fishes; crustaceans, such as hermit crabs and shrimps; and other small invertebrates (in-VER-teh-brehts), that is, animals that lack backbones.

Behavior and reproduction: Atlantic hagfishes use slime to protect themselves from predators (PREH-duh-ters), or animals that hunt them for food. Atlantic hagfishes may make both eggs and sperm for part of their life cycle, reproducing as either male or female at other times. Females produce twenty to thirty eggs.

Atlantic hagfishes and people: The skin of Atlantic hagfishes is processed into leather goods and sold as "eel" skin.

Conservation status: Atlantic hagfishes 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.

Schultz, Ken. Ken Schultz's Field Guide to Saltwater Fish. New York: Wiley, 2004.

Web sites:

Bigelow, Henry B., and William C. Schroeder. "Hagfish." Fishes of the Gulf of Maine.http://www.gma.org/fogm/Myxine_glutinosa.htm (accessed on August 28, 2004).

"Hagfish." OceanLink. http://oceanlink.island.net/oinfo/hagfish/hagfish.html (accessed on August 26, 2004).

"The Lowly Hag." Safari Splash.http://7thfloormedia.com/projects/safari/newsletter/wednesday/hagfish.html (accessed on August 26, 2004).