The sea lamprey is a snake-like fish with suction cup mouth, horny teeth, and sharp rasping tongue. It attaches to other fish, penetrates their skin, and feeds on the blood of its victim. The irruption of the sea lamprey in the Upper Great Lakes occurred at a time when both cultural and natural aspects of the Basin ecosystem were experiencing other increasing stresses.  First record of the sea lamprey in Lake Erie was 1921, in Lake Huron 1934, Lake Michigan 1936, and Lake Superior in 1946.  The commercial demise of upper predator fish stocks, especially lake trout and whitefish, followed soon after.