STEPPING PATTERNS IN ANTS .2. INFLUENCE OF BODY MORPHOLOGY

The locomotory behaviour of 12 ant species belonging to four different genera (Formicinae: Cataglyphis, Formica, Lasius; Myrmicinae: Myrmica ) was studied by filming individuals during walking on smoked-glass pl ates. Subsequent multivariate analyses of walking kinematics and footf all positions showed marked species-specific as well as size-dependent differences in the locomotory behaviour. The geometric properties of the footfall patterns resulting from the alternating tripod gait scale to leg dimensions in a geometric manner. At high speed, footprint dis tances between succeeding tripods exceed maximum leg extension, indica ting that ants are 'trotting' from one tripod to the next one with int ermittent aerial phases. In at least one species (Cataglyphis bombycin a), there is evidence for quadrupedal locomotion at the highest speed. The functional relationship between stride length (s, the distance be tween successive footprints of the same foot) and speed (v) was best d escribed by a curvilinear model, s=av(b). Exponent b ranges from 0.3 t o 0.6 and reveals differences between species. Within species, exponen t b is constant, whereas factor a scales to leg length. Females and ma les show metachronal interleg coordination patterns rather than the al ternating tripod coordination pattern seen in workers of the same spec ies.