An "enactive" approach to integrative and comparative biology: thoughts on the table.

We discuss the concept of Enaction as originally proposed by Varela. We attempt to exemplify through two specific topics, sensory ecology and behavior, as well as physiological and behavioral ecology, on which the enactive approach is based. We argue that sensory physiology allows us to explore the biological and cognitive meaning of animal 'private' sensory channels, beyond the scope of our own sensory capacity. Furthermore, after analyzing the interplay between factors that may impose limits upon an animal's use of time and energy, we call for a program of research in integrative and comparative biology that simultaneously considers evolutionary ecology (including physiological and behavioral ecology) and neurobiology (including cognitive mechanisms as well structural design). We believe that this approach represents a shift in scientific attitude among biologists concerning the place of biological and ecological topics in studies of integrative and comparative biology and biological diversity and vice versa.