When an object rests on a surface, such as a table, for example, the downward force it applies to the surface is counteracted by an equal but upwards force, or reaction, applied by the surface. See more at Newton's laws of motion. A response to a stimulus, such as a reflex.
State. Aquatic Invasive Species: Snakehead (PDF | 201 KB). Indiana Department of Natural Resources. Northern Snakehead. Maryland Department of Natural Resources. Northern Snakehead Fish (Channa argus). New York Department of Environmental Conservation.
The northern snakehead is a fish that is traditionally indigenous to China, Russia, North Korea and South Korea. The earliest detection of a nontraditional niche was when the snakehead was found in a freshwater lake in Crofton, Maryland. This occured in 2002.