Definition: the stirrup-shaped small bone or ossicle in the middle ear which is attached to the incus laterally and to the fenestra ovalis, the 'oval window' medially. The oval window is adjacent to the vestibule of the inner ear. The stapes transmits the sound vibrations from the incus to the membrane of the inner ear inside the fenestra ovalis.
Definition: Capable of creating a new organism by combining the genetic material of two gametes, which may come from two parent organisms or from a single organism, in the case of self-fertilizing hermaphrodites.
Definition: 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.