— The spiders’ ability of walking and climbing on different surfaces and in different conditions is taken into account in this paper in order to define and study a suitable spider-model for a future climbing-robot prototype that can autonomously explore dangerous and extra-terrestrial surfaces. Indeed, the spider shows all of the requisites for the exploration in these non-structured environments: low mass, high motion capabilities, climbing abilities and embedded decision elements. In order to understand how the spiders can walk and climb, the attaching mechanisms, the dynamics of the adhesion and the legs’ movements are evaluated. Thanks to this approach structural and dynamic directives for the model are found and the mobility of the real spider can be studied in order to define a suitable bio-mimetic model. The found simplified model is analyzed from a kinematic point of view considering the different conditions of contact and flight for the eight available legs. A kinema...