Asian small-clawed otters (Amblonyx cinerea): resting and swimming metabolic rates |
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Authors: | N Borgwardt B M Culik |
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Institution: | Abteilung Meereszoologie, Institut für Meereskunde an der Universit?t Kiel, Düsternbrooker Weg 20, D-24105 Kiel, Germany e-mail: bculik@ifm.uni-kiel.de Tel.: +49-431-597 38 28; Fax: +49-431-56 58 76, DE
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Abstract: | Open-flow oxygen and carbon dioxide respirometry was used in Neumünster Zoo (Germany) to examine the energy requirements
of six Asian small-clawed otters (Amblonyx cinerea) at rest and swimming voluntarily under water. Our aim was to compare their energy requirements with those of other warm-blooded
species to elucidate scale effects and to test whether the least aquatic of the three otter species differs markedly from
these and its larger relatives. While at rest on land (16 °C, n = 26), otters (n = 6, mean body mass 3.1 ± 0.4 kg) had a respiratory quotient of 0.77 and a resting metabolic rate of 5.0 ± 0.8 Wkg−1(SD). This increased to 9.1 ± 0.8 Wkg−1 during rest in water (11–15 °C, n = 4) and to 17.6 ± 1.4 Wkg−1 during foraging and feeding activities in a channel (12 °C, n = 5). While swimming under water (n = 620 measurements) in an 11-m long channel, otters preferred a speed range between 0.7 ms−1 and 1.2 ms−1. Transport costs were minimal at 1 ms−1 and amounted to 1.47 ± 0.24 JN−1 m−1 (n = 213). Metabolic rates of small-clawed otters in air were similar to those of larger otter species, and about double those
of terrestrial mammals of comparable size. In water, metabolic rates during rest and swimming were larger than those extrapolated
from larger otter species and submerged swimming homeotherms. This is attributed to high thermoregulatory costs, and high
body drag at low Reynolds numbers.
Accepted: 21 December 1998 |
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