Thermal Biology of the Platypus

 
Body Temperature
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).

More on diving!


Torpor

Unlike many other small mammals, there is no evidence that the platypus hibernates or undergoes any sort of torpor (Bethge, 1997).
However, platypi are not active at all times.  They often spend their longer dives (5-7 min) resting inactively while wedged beneath an object at the bottom of the stream (Evans et al., 1994).
Images courtesy http://www.healthsci.utas.edu.au/physiol/mono/Mainpage.html

What are the evolutionary implications of platypus physiology?


Main page
Introduction to
Monotremes
Thermal Biology
Evolutionary Implications
of Thermal Biology
Diving
Special Aspects
of Diving
Literature 
Cited

This page is a class assignment for Animal Physiology at Davidson College.  For questions or comments, please email Will White.