The epidermis, the outermost cell layer of animals and plants totally covering the organism, reacts on its whole surface with voltage responses of pyroelectric (PE) nature to rapid changes of distinct physical influences of the environment (e.g. temperature, pressure). The voltage/time-course of the PE responses depends on dX/dt (X, external influences, e.g. temperature). The PE responses of animal and plant epidermis are corresponding and analogous to the PE responses of the cell wall of the unicellular organism, green alga Valonia utricularis. The epidermis of living animals and plants thus functions as PE detector and transducer. Analogous properties are supposed to exist in the cell walls of other unicellular organisms, too.