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.
Bowfin and Snakeheads: Distinguishing Features. Snakeheads (family Channidae) from Africa and Asia are occasionally imported illegally into Texas. They closely resemble native bowfin (Family Amiidae) but are unrelated. This page depicts one species of snakehead. About 27 others have been identified, some with different color patterns.