Organisms actively compete for environmental resources. They assess their surroundings, estimate how much energy they need for particular goals, and then realize the optimum variant. They take measures to control certain environmental resources. They perceive themselves and can distinguish between “self” and “non-self.” Current empirical data on all domains of life indicate that unicellular organisms such as bacteria, archaea, giant viruses, and protozoa as well as multicellular organisms such as animals, fungi, and plants coordinate and organize their essential life functions (...) through signaling processes. Signaling allows for real life coordination and organization and is a communicative action in which speciesspecific behavioral patterns and sign repertoires are used. Cells, tissues, organs, and organisms that communicate share several key levels that are essential to all life forms and which serve as a uniform tool for investigating biocommunication. (shrink)