Definition: Hydrofoils, or fins, are used to push against the water to create a normal force to provide thrust, propelling the animal through water. The reduction of fin cross-sectional area helps to minimize drag, and therefore increase efficiency. Regardless of size of the animal, at any particular speed, maximum possible lift is proportional to (wing area) x (speed)<sup>2</sup>. Dolphins and whales have large, horizontal caudal hydrofoils, while many fish and sharks have vertical caudal hydrofoils.
Definition: Component found in mineralized skeletal tissue, (a specialized form of biogenic tissue in which the extracellular matrix is mineralized, and which functions in mechanical and structural support.)
Definition: The organization of the system of organs involved with sexual reproduction, e.g., hermaphroditism, monoecy, dioecy/gonochory, gynodioecy, androdioecy, gynomonoecy, andromonoecy, polygamodioecy, polygamomonoecy, apomixis, etc.