Aerobic Energetics of Surface Swimming in the Muskrat Ondatra zibethicus

This is the authors' abstract. We don't add key points for this paper.

The surface swimming of muskrats (Ondatra zibethicus) was studied by forcing individual animals to swim against a constant velocity water current, ranging from 0.2 to 0.75 m/s, in a recirculating water channel. The swimming muskrat was enclosed in a metabolic chamber to monitor oxygen consumption as a measure of the aerobic power input. The metabolic rate (V̇o2) of swimming muskrats at a water temperature of 25 C was found to increase linearly over the range of test velocities. The computed cost of transport exhibited a curvilinear decrease with increasing velocity to a minimum of 0.75 m/s. Observations of free-swimming muskrats showed that they did not swim at the energetically most efficient velocity but at a lower mean velocity of 0.58 m/s. Departure from the expected swimming velocity was believed to be dependent on an addition of anaerobic metabolism to the aerobic metabolism and onset of fatigue at velocities above 0.6 m/s due to high drag.