定義： The largest scale biogeographic division of the earth's surface based on the historic and evolutionary distribution patterns of plants and animals.
定義： A habitat of rolling or flat terrain where grasses predominate. Typically, what is called a meadow has more biodiversity than a grassland as the former contains not only grasses but a significant variety of annual, biennial and perennial plants.
定義： A group of species that exploit the same food resources, and/or use the same feeding or foraging methods. http://en.wikipedia.org/wiki/Guild_(ecology)
定義： Because of the difference in refractive index between air and water (or corneal tissue), a curved cornea is an image-forming lens in its own right. Its focal length is determined by the radius of curvature of the cornea. Many corneal eyes (eg: in land vertebrates) also have lenses, but the lens is flattened and weakened compared with an aquatic lens; most of the refractive power is provided by the cornea. Corneal eyes cannot focus in aquatic habitat.
