Evidently extremely different locomotions of myriapods, Scolopendra and Pachijulus, are organized by the same principle
A.A. Kharkevich Institute of Information Transmission Problems RAS
Bolshoy Karetniy per. 19, GSP-4, Moscow, 127994, Russia
e-mail: karpovich@iitp.ru
The unified description of locomotions for the differently walking animals is developed. This description is based on a simplified picture of one row of the ipsilateral legs and is called "the locomotor system configuration". A comparative analysis of kinematic characteristics of the leg movements in the locomotion process of two species of the Crimean millipedes, Pachijulus flavipes (Diplopoda) and Scolopendra cingulata (Chilopoda), is made using this picture. Although visible manifestations of locomotor coordinations in these millipedes are much different, their locomotions are shown to be organized quite similarly at the functional level. The Scolopendra always walks on the ground "footprint into footprint", which means that the footprint "typed" on the ground by the first (or one of the first from the head) leg is consecutively stepped by all subsequent ipsilateral legs one after another through intervals of phase delay. The same kinematic principle of "walking footprint into footprint" is used by the Pachijulus, though not in support phases (on the ground) but in the return phases of legs (in the air). If one represents these millipedes as the schemes corresponding to their locomotor configurations, then it is sufficient to turn the Scolopendra's locomotor configuration "on the back" to receive the Pachijulus locomotor configuration, and vice versa. Such kinematic identity of the locomotor organizations in taxonomically distant animals raises new questions about the evolution of the locomotor programs.
