Definition: Gravel is an environmental material which is composed of pieces of rock that are at least two millimeters (2mm) in its largest dimension and no more than 75 millimeters.
Definition: (Bipedal jumping.) Behavior related to the upward thrust produced by the rapid, simultaneous extension of the hind legs with the intend to rise in the air
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.
