The Platypus Ornithorhynchus anatinus is one of the
world's three extant egg-laying mammals (order Monotremata) and
inhabits the lakes, rivers and streams of eastern Australia from
the Cooktown area in the north to Tasmania in the south. Equipped
with webbed feet, both fore and aft, as well as a horizontally
flattened tail, similar to those displayed by the placental beavers
(Castor), the streamlined body of the platypus is well
suited for the animal's semiaquatic mode of life.
Because it lays
eggs and some of its bones are like those of living reptiles and
fossilised mammal-like reptiles, the platypus is sometimes referred
to as "primitive", and even a "furred reptile".
But overall it is much more mammalian than reptilian and, far
from being primitive, is said to be highly evolved and sophisticated.
Considering its unique form and behaviour, the platypus is quite
a fantastic mammal and certainly one of Australia's greatest natural
Some morphological features of a very special animal
- Body: The
Platypus has got a streamlined body optimized for foraging underwater.
The male averages 50 centimetres long and weighs about 1.7 Kilograms.
Females are smaller, averaging 43 centimetres long and weighing
about 0.9 kilograms
- Tail: Used
as a stabiliser underwater, the tail stores fat. A plump tail
is a sign of good condition
- Shoulder girdle: Similar
to that of reptiles such as lizards, the platypus's shoulder girdle
has extra bones to support the large muscles needed for digging
with a sideways action
- Ears and Eyes: Acutely
sensitive above the water, these lie in a furrow that closes when
the platypus is submerged
- Fur: The
platypus has one of the mammal realm's most waterproof coats.
It consists of an inner layer of fine hairs that trap air and
an outer layer of longer, flat-bladed hairs, giving excellent
insulation for an animal that spends up to 12 hours each day in
water as cold as 0 degrees Celsius
- Bill: Thousands
of touch-sensitive and electrosensitive pores cover the platypus's
rubbery bill. The latter can detect the electric currents generated
by the muscle activity of small prey and may even be able to sense
the weak electric field generated when water flows over stationary
- Female Urogenital System: The
platypus is a monotreme, which means one-holed, referring to the
cloaca, the opening that serves both reproduction and excretion.
As in birds one ovary is poorly developed and does not function
- Forefoot: Unlike
beavers, otters and water-rats, the platypus swims with alternate
strokes of the forefeet only. The webbing folds back for walking
and burrowing and during the return stroke in swimming
- Spur: The
young of both sexes have a spur on each hind leg. The female sheds
hers during the first year but the adult males retain them all
their life. They are 1.5 cm long, connected to a venom gland and
are capable of inflicting a painful wound. Males become aggressive
during the mating season and sometimes may hurt each other with
the spurs. The venom can cause excruciating pain in humans and
is strong enough to kill a dog
- Reproduction The Platypus is a seasonal breeder
with males and females reching sexual maturity at an age of two
years. Mating occurs from September onwards, apparently occuring
later in southern areas. Eggs are incubated for about six to ten
days. Once hatched in early November, the young is suckled by
the female which has no teats. Milk is produced in large glands
under her skin which can be up to one-third of her body's length.
The milk oozes out onto a patch of fur and the young Platypus
sucks it up. Platypus milk, like that of marsupials and echidnas,
is rich in iron. It has about 60 times more iron than the milk
of cows. The milk also contains about 40 per cent solids compared
with only 12 per cent solids in cow's milk.
The nesting burrows are about three to eight metres long and are
usually found above water level. The female fills the chamber
with wet leaves, probably to create a moist atmosphere for incubation.
The Platypus is known to live for at least 12 years in the wild.
- Diet As an opportunistic predater, the Platypus
feeds on all kinds of insect larvae as well as freshwater shrimp,
bivalve molluscs, frogs and fish eggs.
The Platypus can be found in all freshwater aquatic systems, including
creeks, rivers and lakes of eastern Australia from the Cooktown
area in the north to Tasmania in the south. Important habitat
characteristics include long pools with consolidated, angled banks,
slow flowing waters, mean pool depths of one to two metres, abundant
aquatic vegetation as well as a good supply of benthic invertebrates.
- Foraging Although diurnal activity can be
quite common, the platypus is generally regarded as nocturnal.
Foraging occurs mostly between sunset and sunrise, consisting
of repeated dives of between 20 and 90 seconds duration. After
successful dives, the platypus will sort and chew the captured
prey. Horny buccal pads are used by the adult to grind the food.
Only juveniles have teeth. While the platypus is submerged food
is held in special cheek pouches.
- Conservation status Although not actually
threatened, the distribution and numbers of the platypus throughout
its range have been severely reduced by habitat destruction and
degradation. The platypus is in a vulnerable position because
their range coincides with the most densely populated regions
of Australia, where much of human activity impacts on the waterways.
Caused by the growing demand for water dams were constructed.
The platypus has to compete with introduced animals. Livestock
trample their burrows. Overall it can be seen that there is a
need for research, in particular in the area of spatial and foraging
requirements, so that effective management plans can be developed.
- Evolution or: When a duck met a lonely water-rat...
Two theories attempt to explain the platypus's evolution.
Anatomist William Gregory proposed in 1947 that monotremes (platypuses
and echidnas) are specialised descendants of ancient marsupials.
However, most scientists believe monotremes are the last survivors
of a group of early mammals evolved independently of the creatures
that gave rise to today's marsupials and other mammals.
To Aborigines the platypus is known as Mallangong,
Tambreet or Boonaburra. According to one of their myths, the platypus
resulted from a young female duck's disobedience. Duck lived with
others of their kind in a sheltered river pond. All of them were
in constant fear of Mulloka, the Water Devil, and never strayed
far from their pond. But one day, against the advice of her elders,
Duck ventured downstream and eventually found herself at a patch
of grass on the riverbank. Unaware that this was the territory
of the lonely Water-rat, she climbed out. Hearing duck, Water-rat
emerged, threatened her with his spear and, dragging her underground,
forced her to mate with him. By the time of egg-hatching, Duck
was ashamed to have to lead out two extraordinary offspring. They
had bills and webbed feet, but instead of two feet they had four
and instead of feathers they had fur, while on each hind leg they
had a sharp spike like Water-rat's spear. The first members of
the platypus race were born.
Department of Anatomy & Physiology
University of Tasmania
GPO Box 252-24, Hobart Tasmania 7001, Australia
phone: +61-3-6226 2678, fax: +61-3-6226 2679
Page maintained by Philip Bethge,
last update: 03/07/97