定義： Capable of the biological process in which new individuals are produced by either a single cell or a group of cells, in the absence of any sexual process.
定義： Eye-spots which may be set into a pit to reduce the angles of light that enters, to allow the organism to deduce the angle of incoming light. Lens-like structures may be present, but stemmata, unlike lens eyes, cannot form an image, either for lack of refractive power or retinal resolution.
