Platypus feed only in the water. The animals mainly find
their invertebrate prey by searching along shallow riffles, gleaning items
from submerged logs and branches, digging under banks or diving repeatedly
to the bottom of pools.
Platypus foraging behaviour in a pool begins with an animal
doing a neat, quiet duck dive. The animal swims to the bottom of the channel
and uses its bill to detect and seize prey. Rather than waste time chewing
its food underwater, the platypus temporarily stores prey items in cheek
pouches located at the back of the jaw. It returns to the surface when its
oxygen supply runs low (usually within 30-60 seconds of the time it dived, though
dives of up to 138 seconds have been recorded) and then typically spends about
10-20 seconds masticating and swallowing food before again diving. The use
of dataloggers has confirmed that platypus mainly but by no means exclusively
feed at night, with around 25% of animals tracked along a small Victorian stream
and 40% of animals tracked in a Tasmanian lake observed to forage frequently
during daylight hours.
Platypus typically have a varied diet dominated by insects
(especially caddis fly larvae, but also larval and adult water beetles, water bugs,
and larval mayflies, damselflies, dragonflies, dobsonflies, midges, craneflies and
blackflies). They also dine on freshwater shrimps, snails, “pea shell” mussels,
seed-shrimps (or ostracods), water mites and worms. Burrowing crayfish have been
found to be an important part of the platypus diet at Lake Lea in Tasmania, and trout
eggs are known to be consumed by animals occupying the Thredbo River in New South
Wales. After comparing the invertebrates found in different aquatic habitats with
those identified in platypus cheek pouches, a researcher working in the Kangaroo
Valley of New South Wales has concluded that platypus are particularly partial to the
types of prey occupying edge habitats (defined as including pool margins and backwaters,
the space below overhanging banks and among submerged vegetation and organic detritus),
followed by those in pools and lastly by those associated with riffles.
The platypus’s ability to prey on sizable fish or other vertebrates
is restricted by its lack of true teeth. Remains of a small frog (which may have been
consumed as carrion) have been found in one platypus cheek pouch sample from the Shoalhaven
River in New South Wales. A young platypus is equipped with true molars located at the
back of the jaw, which fall out about the time that a juvenile first enters the water and
begins to eat solid prey. The teeth are replaced by rough grinding pads which grow
continuously to offset natural wear.
Because the platypus is a relatively small, warm-blooded animal,
it needs substantial amounts of food to serve as fuel. Studies in captivity have
shown that adult males require around 15-28% of their body mass in food each day to
maintain good physical condition, with more food consumed in winter and spring than at
other times of year. Similarly, the average daily food intake of animals occupying a
Tasmanian lake has been estimated to be 19% of body mass. Not surprisingly, the amount
of food eaten by lactating females increases markedly as their offspring grow. For
example, daily food consumption by a mother of twins in captivity rose to around 80%
of her body mass just before the young first emerged from the nesting burrow - roughly
three times her daily food consumption in the months before she mated.
Further reading: Bethge, P.,
Munks, S.A., Nicol, S. and Otley, H. (2000). The use of dataloggers to determine
behavioural activity in the platypus. Australian Mammalogy 21: 262-263. 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 A 136: 799-809. Faragher, R.A., Grant, T.R. and Carrick, F.N. (1979).
Food of the platypus (Ornithorhynchus anatinus) with notes on the food of brown
trout (Salmo trutta) in the Shoalhaven River, N.S.W. Australian Journal of Ecology
4: 171-179. Holland, N. and Jackson, S.M. (2002). Reproductive behaviour and
food consumption associated with the captive breeding of platypus
(Ornithorhynchus anatinus). Journal of Zoology (London) 256: 279-288.
McLachlan-Troup, T.A., Dickman, C.R. and Grant, T.R. (2009). Diet and dietary
selectivity of the platypus in relation to season, sex and macroinvertebrate assemblages.
Journal of Zoology 2009: 1-10. Munks, S.A., Otley, H.M., Bethge, P. and Jackson, J.
(2000). Reproduction, diet and daily energy expenditure of the platypus in a
sub-alpine Tasmanian lake. Australian Mammalogy 21: 260-261.
Spatial organisation and movements
Based on radio-tracking studies, the home ranges of neighbouring
female platypus occupying creeks in the Yarra River catchment near Melbourne often
overlap by about half their total length. Adult males occupy areas which are not
necessarily shared with other males but typically overlap the home ranges of two or
more adult females. In cases where male home ranges do overlap, the males appear to
try to avoid each other when active. The home ranges of adult males tracked for a
few weeks in these creek habitats typically include 1-7 kilometres of channel, as
compared to 1-4 kilometres for adult females. Males and females both visit roughly
one-quarter to three-quarters of their total home range in most foraging periods.
However, an adult male has been recorded to travel up to 10.4 kilometres (including
backtracking) in a single overnight period, whereas the longest corresponding distance
for an adult female is 4.0 kilometres.
Along the Goulburn River (where it presumably is much harder for an
adult male to exclude other males from a given area, due to the greater width and
depth of the channel), male home ranges overlap throughout the year, but less overlap is
apparent during the breeding season than at other times of year. Male home ranges have
been found to vary in length from 0.55-2.8 kilometres, corresponding to 2.45-15.45
hectares of foraging area. However, animals do not utilise all parts of their home
range equally, with an intensively used core area typically comprising 30% of the total
home range area. Including backtracking, animals were recorded to travel up to 4.1
kilometres in a given night.
Longer movements by platypus have been documented, including a
radio-tagged adult male that travelled more than 15 kilometres (between two creeks
in the Yarra River catchment) on at least two occasions within a period of 10 weeks.
Based on mark-recapture studies, a young male is known to have moved about 40 kilometres
in the Yarra system over a period of 18 months or less (from Andersons Creek to Steels Creek),
and a young male travelled nearly 48 kilometres in the Wimmera River catchment over a
period of 7 months or less (from the Wimmera River to Mount Cole Creek).
Due to their mobility, platypus may occasionally be seen
in virtually any part of a river system where they occur. With respect to
conservation management, this mobility has three important consequences:
Suitable vacant habitats are predicted to be occupied quite promptly by
platypus through natural colonisation (particularly if the new habitats are located reasonably
close to areas already supporting the species).
Stretches of river or stream which do not support a resident platypus
population may still constitute important habitat for the species, by providing corridors
along which breeding males and dispersing juveniles can travel.
It is essential that manmade structures (weirs, flood fences, culverts,
irrigation control gates, etc.) placed along natural water bodies or manmade channels that
are accessible to platypus should be built in a manner which facilitates safe passage by the
Further reading: Gardner, J.L.
and Serena, M. (1995). Spatial organisation and movement patterns of adult male platypus,
Ornithorhynchus anatinus (Monotremata: Ornithorhynchidae). Australian Journal of
Zoology 43: 91-103. 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. Serena, M. (1994). Use of
time and space by platypus (Ornithorhynchus anatinus: Monotremata) along a
Victorian stream. Journal of Zoology (London) 232: 117-131.