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： Number of individuals in a group that spends the majority of their time in a 24 hour cycle together where there is some indication that these individuals form a social cohesive unit.
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.
