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Quigley, age 13, of Williamsport, Penn., for her question:

WHAT IS A LAMPREY?

Lampreys spawn in clear water streams. The male and female together dig a shallow nest in the stream's bottom where the female deposits the eggs. The adults die after spawning. Larval lampreys called ammocoetes are born blind and toothless, looking very much like worms. They live in the sand and mud for several years before turning into adults with eyes and teeth.

A lamprey is an eel like fish considered by scientists to be one of the least developed vertebrates in the world. A vertebrate is an animal with a backbone.

Unlike most fish, a lamprey doesn't have a bony skeleton. His backbone is actually made of rubbery tissue called cartilage. He has fins on his back but not on his sides. His round mouth has no jaws but can create strong suction. Adults of some species develop horny teeth.

Some lampreys are parasitic and attach themselves to fishes, scraping a hole through the skin and sucking out blood and other body fluids. The adults of the nonparasitic lampreys do not eat. Their digestive organs degenerate, and they live only until the spawning season. Then they spawn and die.

Sea lampreys rank as the most destructive to fishes. They descend to the sea as adults and prey on large fishes.

Some lampreys that spawned in streams flowing into Lake Ontario once entered the upper Great Lakes through the Welland Canal. Later generations of these lampreys no longer descend to the sea, but prey on lake trout, whitefish and other large lake fishes. By the late 1950s, the lampreys had killed most of the lake trout in the Great Lakes. Scientists tried to control them by putting electric fences, called weirs, across streams to prevent the lampreys from spawning. But the weirs were costly and very difficult to maintain.

Researchers then discovered a chemical called TFM that kills lampreys but does not harm other fish in the rivers. The treatment of streams with TFM caused a sharp decline in the number of lampreys by the mid 1960s. Lakes have since been stocked with additional lake trout as well as coho salmon and other fishes.

At one time lampreys were used for food in New England. Smoked "lamper eel,'' as they were called, were considered a delicacy.

A lamprey's skin is smooth, shiny and scaleless. The brook lamprey, which lives in small streams throughout parts of North America, Asia and Europe, grows to be about eight inches long. Larger species can be found in rivers and lakes.

Sea lampreys, which grow to be three feet in length, can be found both in the North Atlantic and North Pacific oceans.

 

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