Study

Diving behaviour, dive cycles and aerobic dive limit in the platypus Ornithorhynchus anatinus

Bethge, Philip; Munks, Sarah; Otley, Helen; Nicol, Stewart

Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, 2003

Peer-reviewedfield observationwild

What they did

Wild platypuses were fitted with time-depth recorders and their dive cycles logged over foraging bouts, with oxygen consumption measurements used to establish the point at which a dive exceeds what aerobic metabolism can supply.

Studied in: Ornithorhynchus anatinus
Sample size: wild platypuses carrying dive-recording instruments

What they found

Foraging dives are short and extremely frequent — typically around thirty to forty seconds, with brief surface intervals, repeated for hours. Most dives fall within the calculated aerobic limit. A foraging platypus may perform well over a thousand dives in a night.

What it means

The authors' reading, and ours. Where they differ, that difference is the point.

How the authors put it

Platypus foraging is a high-frequency, short-duration diving strategy operating largely within aerobic limits rather than a deep-diving one.

How NatureHQ reads it

The number that reframes the animal is the dive count rather than the dive depth. A platypus is not doing anything impressive on a single dive; it is doing an unimpressive dive over a thousand times a night, hunting invertebrates it cannot see, with its eyes shut. That is an enormous energetic commitment, and it explains the appetite — a platypus eats a substantial fraction of its own body weight daily — and why the electrical sense has to be efficient rather than merely present.

Limitations

Instrumented animals may dive differently from uninstrumented ones.
Aerobic dive limits are calculated from oxygen stores and metabolic rate rather than measured directly during a dive.
One region; platypus behaviour varies with water temperature and prey availability.