Аннотация:The article analyses the influence of Jakob von Uexkull (1864-1944) on biosemiotics. This paper aims to describe the several general features of Uexküll's concept of Umwelt (i.e. worlds around animals as they themselves perceive them) which considered animals as interpreters of their environment. As a philosophical background, Uexküll applied the epistemology of I. Kant to his research of animal behavior and animal subjective worlds. The term of Umwelt in the meaning of the subjective world of an organism has been used by Uexkull since 1909. The conception of Umwelt was one of the first comprehensive systems of notions for semiotic biology.