In the semiotic theories of Jakob von Uexküll and Thomas A. Sebeok, umwelt (plural: umwelten; from the German Umwelt meaning "environment" or "surroundings") is the "biological foundations that lie at the very center of the study of both communication and signification in the human [and non-human] animal". The term is usually translated as "self-centered world". Uexküll theorised that organisms can have different umwelten, even though they share the same environment. The term umwelt, together with companion terms Umgebung (an Umwelt as seen by another observer) and Innenwelt (the mapping of the self to the world of objects), have special relevance for cognitive philosophers, roboticists and cyberneticians because they offer a potential solution to the conundrum of the infinite regress of the Cartesian Theater. Discussion Each functional component of an umwelt has a meaning that represents the organism's model of the world. These functional components correspond approximately to perceptual features, as described by Anne Treisman. It is also the semiotic world of the organism, including all the meaningful aspects of the world for any particular organism. It can be water, food, shelter, potential threats or points of reference for navigation. An organism creates and reshapes its own umwelt when it interacts with the world. This is termed a 'functional circle'. The umwelt theory states that the mind and the world are inseparable because it is the mind that interprets the world for the organism. Because of the individuality and uniqueness of the history of every single organism, the umwelten of different organisms differ. When two umwelten interact, this creates a semiosphere. As a term, umwelt also unites all the semiotic processes of an organism into a whole. Internally, an organism is the sum of its parts operating in functional circles and, to survive, all the parts must work cooperatively. This is termed the "collective umwelt" which models the organism as a centralised system from the cellular level upward. This requires the semiosis of any one part to be continuously connected to any other semiosis operating within the same organism. If anything disrupts this process, the organism will not operate efficiently. Uexküll's writings show a specific interest in the various worlds that he believed to exist ('conceptually') from the point of view of the umwelt of different creatures such as ticks, sea urchins, amoebae, jellyfish, and sea worms. The biosemiotic turn in Jakob von Uexküll's analysis occurs in his discussion of the