Giant Galápagos tortoises walk without inverted pendulum mechanical-energy exchange

Abstract

mechanics during walking do not necessarily correspond to high mechanical work and may not result in a high metabolic cost.

The gait dynamics of the modern broiler chicken: A cautionary tale of selective breeding

“…The capacity for these commercial line birds to therefore recover mechanical energy through pendular mechanics is likely to be low as a direct result of their slow walking speeds. This has also been reported in other slow-walking animals [geckos (Farley and Ko, 1997); alligators (Willey et al, 2004); tortoises (Zani et al, 2005); elephants (Ren and Hutchinson, 2008)]. …”

“…However, our study birds were still walking at substantially slower speeds than other ground-running birds and even slower than waddling birds, such as ducks (Usherwood et al, 2008) and penguins (Griffin and Kram, 2000), which also have relatively short legs and exhibit a comparatively narrower range of speeds than ground-running birds. The average duty factor of the commercial lines studied (0.79±0.05) is still representative of other slow-walking animals including humans (Alexander, 1989;Reilly, 2000;Aerts et al, 2000;Zani et al, 2005).…”

Shoulder girdle rotation, forelimb movement, and the influence of carapace shape on locomotion inTestudo hermanni(Testudinidae)

“…As extremely slow muscles generate force quite economically, the combination of a long tripedal stance with powerful body acceleration during the short bipedal phases appears to constitute a reliable mode of walking, probably less metabolically expensive than a faster walk with higher stride frequencies and lower duty factors (Baudinette et al, 2000). Zani and co-workers (Zani et al, 2005;Zani and Kram, 2008) present a similar argument in their findings on energy recovery mechanisms in the giant Galapagos tortoise and the ornate box turtle Terrapene ornata.…”

“…Deducing resultant forces from kinematics alone is speculative, but studies on substrate reaction forces exerted by turtles during terrestrial locomotion are very rare. Zani et al (2005) illustrated the ground reaction forces for a walking trial in their study on the giant Galápagos tortoise Chelonoides nigra (syn. Geochelone elephantopus).…”

“…It prevents a number of basic terrestrial locomotor principles used by other groups of amniotes, such as the lateral bending of the trunk, extensive limb excursions, and variability in footfall sequences and gaits in order to achieve dynamic stability of the body in motion (Gray, 1944;Zug, 1971;Jayes and Alexander, 1980;Hildebrand, 1985;Zani et al, 2005). On land, turtles are slow walkers and appear rather clumsy in their overall performance.…”