Hexapods shift to increasingly stable gaits when climbing on inclined substrates

When terrestrial organisms locomote in natural settings, they must navigate complex surfaces that vary in incline angles and substrate roughness. Variable surface structures are common in arboreal environments and can be challenging to traverse. This study examines the walking gait of katydids (Tettigoniidae) as they traverse a custom-built platform with varying incline angles (30{whitebullet}, 45{whitebullet}, 60{whitebullet}, 75{whitebullet}, 90{whitebullet}) and substrate roughness (40, 120, and 320 grit sandpaper). Our results show that katydids walk more slowly as the incline angle increases, with a decrease of around 0.39 BL/s for every 23{whitebullet} increase in incline, while substrate roughness has no effect on walking speed, even across different inclines. At steeper inclines, katydids are less likely to use an alternating tripod gait, opting instead to maintain more limbs in contact with the substrate during walking. However, rougher substrates reduce this effect, increasing the likelihood that katydids will employ a tripod gait even on steeper inclines. These findings provide insights into how environmental factors influence locomotor strategies in katydids and enhance our understanding of effective locomotor strategies in hexapods.