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Garpike

Garpike (gar) are bony fish classified in the family Lepisosteidae. These fish are differentiated from garfish which belong to the family Belonidae. Garpike were once Longnose gar (Lepisosteus osseus). Photograph by Robert J. Huffman. Field Mark Publications. Reproduced by permission.
abundant and widely distributed, but are now rare. Some species of garpike are found in Mexico, Central America, and the West Indies, and in eastern North America. Garpike are found in shallow waters with dense weeds.

Garpike have a gas bladder, which is well supplied with blood and which is obtaining oxygen. At intervals, garpike rise to the surface to dispel waste air from the bladder and to refill its contents with fresh air. This source of fresh air helps garpike survive in polluted anoxic water, which would be intolerable for other fish. Garpike actually drown if caught in a net that denied access to the surface. It has been postulated that the capability of these fishes to breathe air may have been a factor in their survival to modern times. Gar spend their time either near the bottom or rising to the surface. Gar can develop considerable speed for a short period to obtain food. Garpike are cylindrical in shape like a cigar, have a long jaw equipped with many sharp teeth, and a long, flat snout. Garpike have ganoid scales, which fit together to form a hard armor or shell, rendering the fish difficult to catch. The scale surface is covered with ganoin, a substance that could be polished to a high luster, and is hard enough to protect against a fish spear. The scales of the large gars were used by native Americans for arrowheads. In pre-Columbian cultures, the shells were used for breastplates. Early farmers would at times use gar hides to cover wooden plowshares to make a hard surface.

The longnose gar (Lepisosteus osseus) is cylindrically shaped, and covered with small ganoid scales arranged in regular rows over its body. Its long and slender jaws are equipped with sharp teeth.

The longnose gar is found over a wide expanse of territory eastward from Montana, the Great Lakes to the St. Lawrence River, to Florida, Alabama, Texas, Mexico, and the Mississippi River drainage system. In the southern part of its range, the longnose gar prefers quiet waters with heavy vegetation, while further north these fish are found in less turbid lakes and streams.

Spawning takes place in the spring in shallow waters. Females bulging with eggs are accompanied by several males waiting to fertilize the eggs as they are laid. It is estimated that an excess of 35,000 eggs may be laid by a 3-ft (1 m) female.

The diet of the longnose gar consists mainly of live and dead fish. Gliding near their prey they capture it with a sudden movement. At other times the fish will lie motionless near the surface and suddenly seize an unwary fish swimming by.

Garfish have no commercial value. In some areas these fish are used for human consumption, but not considered a prized sport fish.

The shortnose gar (L. platostomus) resembles the longnose gar but has shorter jaws, and a short, broad snout. It is the smallest of the gars, rarely more than 2.5 ft (76 cm) long, and is found in the Mississippi River drainage basin.

The largest of the gars in North America is the alligator gar (L. spatula) found in the streams entering the Gulf of Mexico. This species may reach a length of 10 ft (3 m) and 300 lb (136 kg) in weight, and is highly voracious and is considered especially dangerous to human beings.

Resources

Books

Dickson Hoese, H., and R.H. Moore. Fishes of the Gulf of Mexico, Texas, Louisiana and Adjacent Waters. College Station: Texas A&M University Press, 1977.

Migdalski, E.C., and G.S. Fichter. The Fresh and Salt Water Fishes of the World. New York: Greenwich House, 1983.

Moyle, Peter B., Joseph Cech. Fishes: An Introduction to Ichthyology. 4th ed. New York: Prentice Hall, 1999.

Whiteman, Kate. World Encyclopedia of Fish & Shellfish. New York: Lorenz Books, 2000.


Nathan Lavenda

KEY TERMS

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Ganoid scales

—Thick scale composed of rhomboid bony plates covered with an enamel-like substance called ganoin, which is characteristically found in some primitive fishes. Its hard surface provides an excellent protective mechanism.

Gas bladder

—A pouch connected to the throat provided with a blood supply. It helps the fish obtain a better supply of oxygen.

Lateral line

—A row of pores on the side of the tail and trunk, enabling the fish to detect low-intensity vibrations, movement, and possibly pressure changes.

Additional topics

Science EncyclopediaScience & Philosophy: Formate to Gastropoda