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.
Background. The northern snakehead fish (Channa argus) has been identified as an invasive aquatic fish across the country. Snakehead fish got their name because of their long, cylindrical body plan and large scales on their head that give them a snake-like appearance.
California Fish Species. Freshwater native and non-native fish species present currently and/or historically, determined from the PISCES database (Feb. 26, 2014). Some species, such as salmon or steelhead, may no longer be present upstream of dams that lack fish passage.