The platypus maintains a body temperature of 31-32°C (Bethge, 1997).  This is lower than the eutherian norm of about 38°C, and was previously thought to represent "imperfect" evolution of homeothermy (Anderson and Jones 1967).  It is now known that the platypus is a competent homeotherm and can maintain a relatively constant body temperature in ambient air temperatures ranging from 0.5 to 25°C (Bethge, 1997).

The thermal neutral zone of the platypus ranges from 25-35°C (Bethge, 1997).  Within this temperature range, the animal can maintain a constant body temperature without altering its metabolism by changing the conductance of its body surfaces (Schmidt-Nielson, 1997).

Thermoregulation in Water

Platypi are extremely good at surviving in cold water, especially given their relatively small size.  They have been observed continuously foraging in 0°C water for up to 7 hours and can maintain a 31°C body temperature in 5°C water (Bethge 1997).

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