German biologist Jakob von Uexküll focused on how an animal, through its behavioral relations, both impacts and is impacted by its own unique environment. Onto-Ethologies traces the influence of Uexküll's ideas on the thought of Martin Heidegger, Maurice Merleau-Ponty, and Gilles Deleuze, as they explore how animal behavior might be said to approximate, but also differ from, human behavior. It is the relation between animal and environment that interests Heidegger, Merleau-Ponty, and Deleuze, and yet it is the differences in their approach to Uexküll (and to concepts such as world, body, and affect) that prove so fascinating. This book explores the ramifications of these encounters, including how animal life both broadens and deepens the ontological significance of their respective philosophies.