Platypus feed only in the water. They find small invertebrates by searching along shallow riffles or submerged logs and branches, digging under banks, and diving to the bottom of pools. A platypus most often feeds for one long session in each 24-hour period, typically remaining active for 8-16 hours (Serena 1994; Gust and Handasyde 1995; Otley et al. 2000; Bethge et al. 2003, 2009), though up to 30 hours of continuous activity can occur (Bethge et al. 2009). Up to 1600 foraging dives may be completed in a given session (Bethge et al. 2003).
Platypus foraging behaviour in a pool begins with an animal doing a neat, quiet duck dive (as shown above). The animal then swims to the bottom and uses its bill to find and seize prey. The platypus doesn’t swallow food items immediately, instead storing its prey in special cheek pouches located near the back of its bill. It returns to the surface as its oxygen supply becomes depleted, usually spending less than 60 seconds underwater (Kruuk 1993; Bethge et al. 2003) though an unforced dive lasting 138 seconds has been recorded (Bethge et al. 2003). A platypus will then typically remain on the surface for 10 to 20 seconds as its chews its prey and breathes, before diving again (Kruuk 1993; Bethge et al. 2003).
Although platypus cheek pouches sometimes contain trace amounts of mud or sand, such material is presumably ingested by accident. In particular, there’s no reason to believe that gritty sediment is retained on purpose to help grind up prey. Instead, inedible material is probably routinely expelled (along with surplus water) through grooves located along the edge of the lower jaw (as shown at left) (Grant 2007).
An insulating air layer trapped in the platypus’s fur increases buoyancy and hence the amount of energy required to dive deeply. At Lake Lea in Tasmania (which has a maximum depth of more than 10 metres), 98% of platypus dives did not exceed 3 metres, though one dive descended to nearly 9 metres (Bethge et al. 2003). On the other hand, in a relatively shallow segment of the lower Hastings River in New South Wales (where 61% of the channel was less than 1 metre deep), 91% of platypus dives occurred in places where the water was deeper than 1 metre (Grant 2004). Taken together, these results suggest that a platypus foraging behaviour ideally occurs at a depth of 1 to 3 metres. The use of data loggers has also confirmed that this species feeds mainly but by no means exclusively at night, with around 25% of animals tracked along a small Victorian stream sometimes foraging during daylight hours (Serena 1994). In a subalpine Tasmanian lake, 61% of platypus foraging trips were exclusively nocturnal, with 8% of trips restricted to daylight hours and 31% occurring partly during the day and partly at night (Bethge et al. 2009). Animals occupying a creek in southern Tasmania have also been found to adjust the timing of their activity during drought so they became increasingly nocturnal as the channel held less water. This change presumably occurred to reduce the risk that they were detected and killed by a predator, particularly while travelling along dry stretches of the creek bed between pools (Roberts and Serena 2025, see https://www.publish.csiro.au/mf/pdf/MF25030 for more details).
Photos courtesy of Ann Killeen (bottom); APC (top)
LITERATURE CITED
Bethge P, Munks S, Otley H and Nicol S (2003) Diving behaviour, dive cycles and aerobic dive limit in the platypus Ornithorhynchus anatinus. Comparative Biochemistry and Physiology Part A 136, 799-809.
Bethge P, Munks S, Otley H and Nicol S (2009) Activity patterns and sharing of time and space of platypuses, Ornithorhynchus anatinus, in a subalpine Tasmanian lake. Journal of Mammalogy 90, 1350-1356.
Grant T (2007) Platypus. CSIRO Publishing: Collingwood VIC.
Grant TR (2004) depth and substrate selection by platypuses, Ornithorhynchus anatinus, in the lower Hastings River, New South Wales. Proceedings of the Linnean Society of New South Wales 125, 235-241.
Gust N and Handasyde K (1995) Seasonal variation in the ranging behaviour of the platypus (Ornithorhynchus anatinus) on the Goulburn River, Victoria. Australian Journal of Zoology 43, 193-208.
Otley HM, Munks SA and Hindell MA (2000) Activity patterns, movements and burrows of platypuses (Ornithorhynchus anatinus) in a sub-alpine Tasmanian lake. Australian Journal of Zoology 48, 701-713.
Roberts S and Serena M (2025) Behavioural flexibility of the platypus (Ornithorhynchus anatinus) in response to changing water depth in a drought-affected Tasmanian stream. Marine and Freshwater Research 76, MF25030.
Serena M (1994) Use of time and space by platypus (Ornithorhynchus anatinus: Monotremata) along a Victorian stream. Journal of Zoology 232, 117-131.