Authors: Philipp Bußhardt Stanislav N Gorb
Publish Date: 2014/03/19
Volume: 200, Issue: 5, Pages: 385-398
Abstract
We measured ground reaction forces in fore–aft and normal directions of single hind and front legs in vertically ascending Sagra femorata beetles Coleoptera Chrysomelidae on a smooth and a rough substrate Simultaneously we performed electromyographic recordings EMGs of the hind leg claw retractor muscle that partly controls the attachment structures On both substrates hind legs produced upward as well as downwarddirected forces during one stance phase Forces were equivalent in both directions Front legs generated only upwarddirected forces The main function of hind legs in ascending beetles in the second half of the stance thus probably prevented the animals from tilting away from the substrate The EMGs of hind legs showed an early spike during stance with large amplitude It was mostly followed by few additional spikes with large amplitude and in some cases of spikes with smaller amplitude distributed throughout the stance phase We found significantly more spikes on the rough substrate than on the smooth one This is probably due to the more important role of pretarsal claws than tarsal hairy attachment pads on the rough substrate or to the reduced adhesive forces on the rough substrate that have to be compensated by additional muscle activity
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