High-speed locomotion in the Saharan silver ant, Cataglyphis bombycina

Abstract

The diurnal thermophilic Saharan silver ant, Cataglyphis bombycina, is the fastest of the North African Cataglyphis desert ant species. These highly mobile ants endure the extreme temperatures of their sand dune environment with outstanding behavioural, physiological and morphological adaptations. Surprisingly, C. bombycina has comparatively shorter legs than its well-studied sister species Cataglyphis fortis from salt pan habitats. This holds despite the somewhat hotter surface temperatures and the more yielding sand substrate. Here, we report that C. bombycina employs a different strategy in reaching high running speeds, outperforming the fastest known runs of the longer-legged C. fortis ants. Video analysis across a broad range of locomotor speeds revealed several differences to C. fortis. Shorter leg lengths are compensated for by high stride frequencies, ranging beyond 40 Hz. This is mainly achieved by a combination of short stance phases (down to 7 ms) and fast leg swing movements (up to 1400 mm s−1). The legs of one tripod group exhibit almost perfect synchrony in the timings of their lift-offs and touch-downs, and good tripod coordination is present over the entire walking speed range (tripod coordination strength values around 0.8). This near synchrony in leg movement may facilitate locomotion across the yielding sand dune substrate.

Uneven substrates constrain walking speed in ants through modulation of stride frequency more than stride length

“…According to allometric scaling equations [45], this transition should occur in Argentine ants The stride lengths of ants walking on flat ground primarily range from 1.8 to 2.6 mm, but large relative variations obscure a tight correlation with speed (figure 4b). The slope of the relationship between stride length versus speed is 0.03 s, which falls within the range of published values for ants [25,46], cockroaches [47] and fruit flies [48][49][50]. Given our large sample size, we rely more on effect size and the coefficient of determination (R 2 ) instead of p-values to represent the regression [51,52].…”

Adaptations to thermal stress in social insects: recent advances and future directions

“…As a result, foragers can hold their bodies up off the hot ground; an increase of just a few millimetres in leg length can reduce the air temperature surrounding the body by as much as 4°C (Sommer & Wehner, 2012; Centorame et al ., 2019). In addition, longer legs allow foragers to run faster, thereby maximising convective cooling and reducing the time spent outside the nest (Hurlbert, Ballantyne, & Powell, 2008; Sommer & Wehner, 2012; Pfeffer et al ., 2019). Valley carpenter bees ( Xylocopa varipuncta ) also use active convective cooling to fly at very high temperatures without overheating (Heinrich & Esch, 2018).…”

How Can Interfacial Phenomena in Nature Inspire Smaller Robots

“…[ 151 ] The Saharan silver ant ( Cataglyphis bombycina ) exhibits a maximum walking speed of ≈1 m s −1 which is around 108 BL s −1 . [ 152 ] Among other fast running insects, the American cockroach ( Periplaneta americana ) is capable of achieving a running speed of 1–1.5 m s −1 or 50 BL s −1 through changing the stepping pattern. [ 153 ] Fast release of potential energy is a key mechanism in order to induce fast locomotion, including running, jumping and flying.…”