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Energetics of foraging and locomotion in the platypus Ornithorhynchus anatinus

journal contribution
posted on 2023-05-16, 13:09 authored by Bethge, P, Sarah MunksSarah Munks, Stewart NicolStewart Nicol
We measured the energy requirements of platypuses foraging, diving and resting in a swim tank using flow-through respirometry. Also, walking metabolic rates were obtained from platypuses walking on a conventional treadmill. Energy requirements while foraging were found to depend on water temperature, body weight and dive duration and averaged 8.48 W kg-1. Rates for subsurface swimming averaged 6.71 W kg-1. Minimal cost of transport for subsurface swimming platypuses was 1.85 J N-1m-1 at a speed of 0.4 m s-1. Aerobic dive limit of the platypus amounted to 59 s. Metabolic rate of platypuses resting on the water surface was minimal with 3.91 W kg-1 while minimal RMR on land was 2.08 W kg-1. The metabolic rate for walking was 8.80 W kg-1 and 10.56 W kg-1 at speeds of 0.2 m s-1 and 0.3 m s-1, respectively. A formula was derived, which allows prediction of power requirements of platypuses in the wild from measurements of body weight, dive duration and water temperature. Platypuses were found to expend energy at only half the rate of semiaquatic eutherians of comparable body sizes during both walking and diving. However, costs of transport at optimal speed were in line with findings for eutherians. These patterns suggest that underwater locomotion of semiaquatic mammals have converged on very similar efficiencies despite differences in phylogeny and locomotor mode.

History

Publication title

Journal of Comparative Physiology B-Biochemical Systemic and Environmental Physiology

Volume

171

Issue

6

Pagination

497-506

ISSN

0174-1578

Department/School

Tasmanian School of Medicine

Publisher

Springer-Verlag

Place of publication

New York

Repository Status

  • Restricted

Socio-economic Objectives

Expanding knowledge in the environmental sciences

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