|
Platypus reproduction
Return
to Platypus Page
-
The platypus is a warm-blooded mammal which lays and hatches
eggs.
-
A female platypus produces a clutch of one to three eggs in late winter or
spring.
-
The eggs are 15-18 millimetres long and have a thin, leathery shell,
like those of snakes and lizards.
-
The mother is believed to incubate them
between her lower belly and curled-up tail for a period of about 10 or 11 days
as she rests in an underground nest made of leaves or other vegetation collected
from the water.
-
A female platypus does not have nipples.
-
Instead, a rich milk
is secreted from two round patches of skin midway along the mother's belly.
-
It
is believed that a baby platypus feeds by slurping up milk with rhythmic sweeps
of its stubby bill.
-
When the juveniles first enter the water at the age of about
four months, they are nearly (80-90%) as long as an adult.
-
Male platypus do not help to raise the young.
Breeding season
Return
to Platypus Page
-
Platypus eggs have been recorded in nests from August to
October, with some evidence that the animals breed a few weeks earlier in
Queensland as compared to Victoria and Tasmania.
-
As platypus eggs are believed
to develop for about a month inside the mother after being fertilised, platypus
presumably breed as early as July in the warmer parts of their range.
Platypus
Reproduction Table
Size
Return
to Platypus Page
-
Male and female platypus are both believed to be capable of
first reproducing at the age of two years.
-
At maturity, male platypus measure on
average 50 centimetres in total body length (bill tip to tail tip).
-
They
typically weigh 1.2-2.6 kilograms, although the heaviest platypus yet recorded
(captured in Tasmania) tipped the scales at 3 kilograms.
-
Adult females are
smaller, measuring an average 43 centimetres in total body length and weighing
0.7-1.6 kilograms.
-
The
platypuses found in the Wet Tropics (the northern limit of the platypus) are
noticeably smaller than those are elsewhere.
Life span
Return
to Platypus Page
-
Platypus have been recorded to live to at least 16 years in
the wild, though most individuals die at a much younger age.
-
The longest
reliable age record for a platypus in captivity is 17 years.
-
More research is
required to establish the animals' typical life span in the wild, although
estimates of about 4-5 years for males and 6-8 years for females are not
unreasonable.
-
Determining the exact age of a wild adult platypus is very
difficult. In the case of younger animals, some information can be gained by
examining the inner hind ankle.
-
From the time they first leave the nesting
burrow, juvenile males are equipped with a conspicuous cone-shaped spur
(initially about 1 centimetre long) on each hind leg.
-
At first the spurs are
protected by a white chalky layer, which gradually chips away to reveal the
slightly curved true spur by the age of about one year.
-
Juvenile females have
tiny spurs, 1-2 millimetres long, which are shed by the age of about 10 months,
leaving only a small pit to mark the spot.
Predators
Return
to Platypus Page
-
Reports by naturalists indicate that very large Murray cod
and birds of prey (hawks, eagles and owls) occasionally capture platypus in the
water, while carpet pythons, goannas and Australian water-rats may attack young
platypus in the burrow.
-
It has also been suggested that predation by crocodiles
may contribute to the lack of platypus on Cape York Peninsula in far north
Queensland. Since European settlement, introduced species such as foxes, dogs
and cats have also become predators on platypus.
Effect of floods
Return
to Platypus Page
-
Anecdotal evidence suggests that some platypus may die in
severe floods.
-
However, flooding may also benefit platypus populations by
temporarily expanding the size of the area available for foraging.
Human Impact
- Humans are a threat to the platypus, as well as its natural
enemies like snakes, water rats, goannas, and introduced foxes.
- Platypuses
were shot and trapped extensively in the early 1900s for their fur until
legislation protected them.
- They are also threatened by pollution of waterways, erosion
of stream banks, the building of dams, and stream improvement works.
- Natural
vegetation along waterways should be maintained to protect the banks and
provide platypus habitat.
Some unintentional problems humans cause towards
platypuses:-
- drowning if entangled in fishing line, nets and litter
- becoming caught on fish hooks
- damaging their bills on glass, tin cans and other sharp
objects
- losing the waterproof qualities of their fur due to oils
and other chemicals
- getting pulled into pumps with intake pipes below water
level
- having burrows destroyed from erosion, degradation of
riverside vegetation and concrete channelisation
- losing food if insecticides or other chemicals kill their
invertebrate prey
- getting attacked by cats and dogs.
Disease
Return
to Platypus Page
-
Few life-threatening illnesses have been reported in wild
platypus, other than cases of bacterial pneumonia which probably developed after
water was aspirated into an animal's lungs.
-
Platypus living in some parts of Tasmania are also known to
suffer from a fungal disease, Mucor amphibiorum,
which can cause serious skin abscesses and ulcers.
-
Fortunately, no cases of this
disease have yet been found on the Australian mainland.
|
