Study
Temperature Regulation in the Platypus, Ornithorhynchus anatinus: Production and Loss of Metabolic Heat in Air and Water
Grant, T. R.; Dawson, T. J.
Physiological Zoology, 1978
Metabolic rate and body temperature were measured in platypuses across a range of air and water temperatures, establishing how the animal maintains its body temperature in a medium that removes heat far faster than air does.
- Studied in
- Ornithorhynchus anatinus
- Sample size
- metabolic measurements across air and water temperatures
The platypus maintains a body temperature of about 32°C, several degrees below the typical placental mammal, and holds it stably even in water near freezing. Heat loss is controlled by exceptionally dense fur that traps an insulating air layer, and metabolic rate rises to compensate in cold water.
What it means
The authors' reading, and ours. Where they differ, that difference is the point.
How the authors put it
Monotreme thermoregulation is fully effective at a lower set point, and the low body temperature reflects a different setting rather than a deficient system.
How NatureHQ reads it
This measurement retired a long-standing story. The low body temperature had been read as evidence that monotremes were poor at thermoregulation — a "primitive" halfway state between reptiles and proper mammals. What the numbers show is a thermostat working perfectly well at a different setting, in an animal that spends hours a night in cold water, which is a much harder thermal problem than being a mammal in air. The fur is the reason it works: dense enough to hold a layer of air against the skin, so the animal is effectively swimming inside a dry suit.
- Laboratory conditions with controlled water temperature; wild animals also select where and when to forage.
- Older methodology, though the central result has been repeatedly confirmed.
- Does not address the thermal cost of the very long foraging bouts recorded later in the wild.
What this study is used for on NatureHQ
One study can inform several subjects. Here is everywhere this one is cited.
Published by: University press journalsPublished in a university press journal.
doi.org/10.1086/physzool.51.4.30160956
This reference was resolved automatically against Crossref on 2026-08-11.
NatureHQ summarises research in its own words and does not reproduce published text. Reviewed 2026-08-11.