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.
Non-native species can be added to a community either by natural range extensions or because they are introduced as a result of human activity. Most non-native species have harmful ecological effects; these are referred to as invasive species.Virtually all ecosystems are at risk from the harmful effects of introduced invasive species (also see exotic species, marine invasive species, and aquatic invasive species).n invasive species is defined legally in the USA as âAn alien species whose introduction does or is likely to cause economic or environmental harm or harm to human healthâ¦âAlien speciesâ means, with respect to a particular ecosystem, any speciesâ¦that is not native to that ecosystem.â.