title: Energetics of terrestrial locomotion of the platypus Ornithorhynchus anatinus.
abstract: The platypus Ornithorhynchus anatinus Shaw displays specializations in its limb structure for swimming that could negatively affect its terrestrial locomotion. Platypuses walked on a treadmill at speeds of 0.19-1.08 m x s(-1). Video recordings were used for gait analysis, and the metabolic rate of terrestrial locomotion was studied by measuring oxygen consumption. Platypuses used walking gaits (duty factor >0.50) with a sprawled stance. To limit any potential interference from the extensive webbing on the forefeet, platypuses walk on their knuckles. Metabolic rate increased linearly over a 2.4-fold range with increasing walking speed in a manner similar to that of terrestrial mammals, but was low as a result of the relatively low standard metabolic rate of this monotreme. The dimensionless cost of transport decreased with increasing speed to a minimum of 0.79. Compared with the cost of transport for swimming, the metabolic cost for terrestrial locomotion was 2.1 times greater. This difference suggests that the platypus may pay a price in terrestrial locomotion by being more aquatically adapted than other semi-aquatic or terrestrial mammals.
authors.affiliation: Department of Biology, West Chester University, West Chester, PA 19383, USA. ffish@wcupa.edu
authors.forename: F E
authors.initials: FE
authors.lastname: Fish
authors.forename: P B
authors.initials: PB
authors.lastname: Frappell
authors.forename: R V
authors.initials: RV
authors.lastname: Baudinette
authors.forename: P M
authors.initials: PM
authors.lastname: MacFarlane
mesh_terms: D000220:Adaptation, Biological / Q000502:physiology; D000818:Animals; D004734:Energy Metabolism / Q000502:physiology*; D005121:Extremities / Q000033:anatomy & histology; D005260:Female; D006801:Humans; D008124:Locomotion / Q000502:physiology*; D008297:Male; D010101:Oxygen Consumption; D010987:Platypus / Q000033:anatomy & histology / Q000502:physiology*; D012044:Regression Analysis