HABITS
The early records contain little in the way of precise information as
to the general habits of the platypus. Bennett (1860, p. 95) complains
that, as long ago as 1829, “notwithstanding all the inquiries I
made of persons long resident in the colony, I could get no correct
information; I found then, as I have found during an extended residence
in the colony, that the majority preferred forming theories of their
own, and arguing upon their plausibility, to devoting their time to the
collection of facts.” It is the same to-day.
Bennett went out to seek his first platypus at sunset, “knowing, as
I did, the crepuscular nature of the animals,” and it was not long
before his companion directed his attention to one on the surface of
the water, not far from the bank on which they were standing. He writes
(_loc. cit._, p. 104):--
“In such circumstances they may be readily recognized by their dark
bodies just seen level with the surface, above which the head is
slightly raised, and by the circles made in the water around them
by their paddling action. On seeing them, the spectator must remain
perfectly stationary, as the slightest noise or movement will cause
the timid creature instantly to disappear, so acute are they in
sight or hearing, or perhaps in both; and they seldom reappear when
once frightened. By remaining perfectly quiet, however, when the
animal is paddling about, it is possible to obtain an excellent
view of its movements on the water; it seldom remains longer than
one or two minutes playing on the surface, but dives, and reappears
a short distance above or below the place at which it was observed
to descend. Although the animal may ‘come up’ close to the place
where the sportsman is standing, it would be useless to attempt to
level the gun, for that action alone would cause its instantaneous
disappearance; but, after waiting patiently until the animal dives,
and watching the direction in which it sinks, preparation must be
made to receive it with the discharge of the piece instantly on its
reappearance at the surface, which (when it descends unfrightened) is
almost certain to take place in a short time.”
And again on p. 108:--
“These creatures are seen in the Australian rivers at all seasons of
the year, but are most abundant during the spring and summer months,
and I think a question may arise whether they do not hibernate. The
best time for seeing them is early in the morning, or late in the
evening. During floods and freshes, they are frequently perceived
travelling up and down the rivers: when going down, they appear
to allow themselves to be carried by the force of the stream,
without making any exertion; but when swimming against the current,
their muscular power is exerted to the utmost to stem its force,
and generally with success. I recollect, however, seeing two make
repeated and ineffectual attempts to pass a small waterfall in a
rapid part of the river, and, after many persevering efforts, they
were unable to attain their object. The opinion that so generally
prevails that these animals must be shot dead instantly, or otherwise
they would sink and not reappear, I did not find from my own
observations to be correct.”
These observations are of special interest, since they were made as
long ago as 1829 in a district which had but recently been settled,
so that the platypus could not have had time to alter its ways on
coming into contact with Europeans. More than sixty years later
the distinguished German zoologist Richard Semon spent some time
on the Burnett River, where he reports that the platypus was very
plentiful and was not molested by the white colonists or hunted by
the aborigines. His account of its habits agrees in all essential
particulars with that of Bennett. In the English translation of his
popular account of his journey (Semon, 1899) will be found a summary of
his observations; I prefer to give a translation from his paper in the
_Forschungsreise_, which is somewhat fuller. He writes (p. 10):--
“On the Upper and Middle Burnett, where alone I observed the
animal, it was plentiful everywhere in suitable localities along
the river. In _Ornithorhynchus_ a considerable preponderance of
males over females was observed, so that for each female captured
there were two or three males. As in Echidna, the fully grown male
is larger than the female. Like Echidna, too, _Ornithorhynchus_
does not lead an exclusively nocturnal life. More than once I saw
the animals swimming in the river in daylight, searching for food;
yet this could be termed exceptional. It is during the twilight of
morning and evening that the animal leaves its home and passes to
the water. Generally they turn to the river shortly before sunrise,
and remain there till the sun has completely risen. In the evening
it is the same--from a short time before sunset to a little while
afterwards, a period of twenty to thirty minutes. This holds good
for the winter months, from June to the beginning of September, when
the nights are cold and the thermometer in the mountainous regions
of the Burnett is almost at freezing point. One is then sure to meet
with plenty of _Ornithorhynchus_ at suitable places both morning
and evening; and now and again to see them in broad daylight. This
is changed, however, when the Australian summer begins. The days
become hot, and the nights warm. In the middle of September, during
1891 and 1892, I very seldom found an _Ornithorhynchus_ in the river
during the morning and evening hours, and still less frequently by
day. Doubtless they then use the nights for these excursions, for
they must enter the water to obtain their food. I took great pains
actually to observe the animal in the river by night. I did not
succeed, however, nor even in bright moonlight. Since, however,
_Ornithorhynchus_ lies flat like a plank in the water, scarcely
projects beyond the surface, and is absolutely noiseless in diving
and reappearing, one would need an exceptionally favourable occasion
to perceive and observe the animal by night.
“In the cool part of the year, on the other hand, I could observe
the behaviour of the animal in the river during dawn and during
daylight as long as the sun was low. As has been already mentioned,
_Ornithorhynchus_ lies quite flat in the water, with only the flat
head projecting, and that very inconspicuously. Usually the animal
lies motionless at the surface. After a few minutes it dives suddenly
and noiselessly, stays under water two or three minutes, and comes up
again just as suddenly, and just as noiselessly. During its dive it
has collected by means of its flat bill, after the manner of a duck,
all sorts of aquatic life, and richly filled its cheek-pouches. The
reappearance takes place in order that it may get air, and chew and
swallow the contents of these pouches....
“If an animal is frightened while in the water, it dives immediately,
and does not reappear. Although it is a good diver, it can only spend
a certain amount of time under water. Those which become accidentally
caught in fishing-nets at night, and are held fast for a long time
under water, are always found drowned next morning.
“The pursuit of the animal is not difficult if one knows its habits.
Small as is its eye, and deeply buried in the fur as is the opening
of the ear, yet sight and hearing are distinctly sharp; it is
therefore useless to begin matters by trying to creep up while the
animal is at the surface. The position of the eyes enables it to
observe exactly what is going on on the rising banks above it. It
does not recognise danger, however, unless the observer moves. But
the mere lifting of a gun is sufficient to scare the animal away.
Every dubious noise causes it to disappear.... Once scared off, the
animals nearly always seek their homes, and do not reappear during
that same morning or evening. And yet, it is easily taken if one
approaches while it is under water, and at once stops motionless when
it appears.”
These accounts of two very competent observers, both made in districts
where the animal had not yet been disturbed or harassed, show that
the platypus has not developed its alertness and timidity since the
advent of man. The same remark applies to its predominantly crepuscular
habits. It has sometimes been erroneously claimed that these have been
adopted to escape from man and his gun. It must also be remarked that
the months during which Semon noted occasional animals in the water by
day are those of the breeding-season. At that season, when opening up
burrows containing suckers, I have frequently found that the mothers
were absent. It seems certain that they are forced to feed at irregular
times during the nursing period, and that this is the principal reason
for their being found in the river in broad daylight.
As to the preponderance of males noted by Semon, here again we must
consider the time at which the observations were made. Wilson and
Hill (1908, pp. 33-4) state:--“During the breeding-season, however,
the pregnant female appears to keep much more closely to the burrow,
so that one may then commonly enough shoot five or six males to one
female.” As far as my observations go, the sexes seem to be numerically
about equal.
A few other earlier observations are of interest. It is worth
remembering that Charles Darwin (1845) saw the platypus with his own
eyes. On January 19, 1836, while staying a day at “a farm called
Walerawang,” he had the following experience.
“In the dusk of the evening I took a stroll along a chain of ponds,
which in this dry country represented the course of a river, and
had the good fortune to see several of the famous _Ornithorhynchus
paradoxus_. They were diving and playing about the surface of the
water, but showed so little of their bodies that they might easily
have been mistaken for water-rats. Mr. Brown shot one: certainly it
is a most extraordinary animal; a stuffed specimen does not at all
give a good idea of the appearance of the head and beak when fresh,
the latter becoming hard and contracted.”
Crowther (1879, p. 97) gives the only detailed description of its
swimming motions known to me:--
“When swimming, the fore-paws are widely expanded, being convex
forwards, propelling themselves by an antero-lateral movement. The
hind paws and tail take but little share; the former have a slight
lateral horizontal movement, the tail lazily moving with the body.
When diving, the head is rapidly thrown beneath the body, front
paws quickly moving until the bottom is arrived at, when they are
seen turning rapidly over with their bills the sand, and even large
stones.... A train of small bubbles proceeding from the nose marks
the exact course the animal is taking.”
Crowther also states that the tail is the first part to reach the
surface of the water.
Allport (1878, pp. 30-31) also watched ‘a large specimen, and one
of that variety which has very red fur on the sides’ feeding over a
gravelled bottom in the clear waters of the Mount River (a tributary
of the Huon) in Tasmania; “his method of proceeding was to burrow his
head and more than half the body amongst the stones, causing a cloud of
sediment to rise at each dive.... He never remained under water longer
than a trifle over half a minute, and stayed on the surface between
the dives rather less than half a minute.” Allport also records that
a large number of small bubbles were continuously emitted, and that
the animal fed for three-quarters of an hour, and then went off to
his burrow. I also have observed platypus feeding in clear water, and
have seen them tear stones aside with their claws, or lever them up
with their powerful bills and shoulders, to get at food underneath;
but bubbles are certainly not emitted continuously while the animal
is under water, as all platypus-hunters know. When it dives in alarm,
the breath is apparently held, and no tell-tale bubbles issue. The
first bubbles that come to the surface, after the animal dives, are
not emitted by the platypus at all, but are formed by the imprisonment
of air when the bill is suddenly submerged, and, as the body turns
downwards, the bubbles traverse the contour of the back and break away
at the rump to ascend rapidly to the air. This was formerly believed
to be escaping breath; but as the animal, before sounding, undoubtedly
fills its lungs to the utmost capacity so that it may remain under
water, if need be, for several minutes in search of food, it is not
likely to exhale until compelled to do so, and then only in brief
spasmodic puffs.
From the sum of these observations, and without drawing further upon my
own, we may safely conclude that the platypus is normally crepuscular,
and was so before the advent of European man; that it resorts to the
water twice daily to feed, and remains there for a period of from
twenty minutes to three-quarters of an hour, perhaps longer when food
is scarce; that the sum total of its aquatic life amounts to less than
two hours out of each twenty-four; that it is so wary as to disappear
for the day at the first sight of some unaccustomed movement on the
river-bank, or the hearing of some unaccustomed noise close at hand;
that while feeding undisturbed it remains at the surface for a period
variously estimated at from rather less than half a minute to one
minute, for the purpose of chewing and swallowing its catch, and then
dives to collect more food, remaining under water for a similarly
varied time; that in feeding it burrows with its sensitive, tactile
muzzle among mud and stones, sometimes burying more than half its body,
and thrusting fairly large stones aside with its powerful shoulders;
that the greatly webbed fore-paws are the chief swimming-organs; and
that, when floating at the surface, it lies flat, with the body just
submerged except for the upper part of the flattened head and the
middle of its back and tail, though occasionally it will be seen as in
Plate 5, fig. 2.
Most of those which have occasionally been observed during the daytime
(especially during the breeding-season) are undoubtedly females; but
in well-shaded pools it is not uncommon to see individuals of both
sexes abroad during the day. The time spent in feeding is bound to vary
according to the supply of the invertebrate fauna and other commodities
which constitute its food at that particular period of the year. Where
food is plentiful, an adequate meal can be collected quickly, and the
time required may be no more than Semon’s minimum of twenty minutes.
The gravel bank referred to by Allport would not be so productive as
a silt-bottomed water-hole, full of aquatic plants, in the Burnett,
and it might easily take three-quarters of an hour to obtain a full
meal. The nature of the food itself has been variously reported. For
the Burnett, Semon (1894, p. 11) reports that the main food consisted
of molluscs, and that the cheek-pouches were usually found to be full
of immature individuals of a bivalve, _Corbicula nepeanensis_, 10 to
15 mm. in length. He mentions in addition, however, worms and insect
larvae. Bennett (1860, p. 113) writes:--
“On examining the cheek-pouches or the stomachs of these animals,
I always observed the food to consist of _débris_ of insects of
the family _Nauceridae_, very small shell-fish, etc., which were
constantly found comminuted and mingled with mud or gravel. This
latter might be required to aid digestion, as I never observed the
food unmingled with it. The natives say that they also feed on
river-weeds; but as I have never seen that kind of food in their
pouches, I cannot confirm the correctness of the statement.”
Allport (_loc. cit._) states that the food found in the cheek-pouches
consisted of larvae of caddis-flies; Crowther found freshwater shrimps,
water-fleas, and hard black beetles.
Wood Jones (1923, p. 55) notes that Bennett recorded the feeding of
captive animals on freshwater mussels; but the mussels were broken up
before they were given. From the nature of the masticatory apparatus
he argues against shell-fish as a diet, and he concludes that common
river-shrimps may be regarded as the staple article of diet. Since such
thoroughly competent observers as Semon and Bennett have both actually
found molluscs in the cheek-pouches, these cannot be put out of
consideration as food. There is, moreover, a great deal of difference
between the ‘very small shell-fish’ which Bennett mentions, and the
large swan-mussels which were probably (though it is not specifically
stated) the kind given in broken form to the captives. All observers
agree that the platypus finds its food by nuzzling in the mud or gravel
of the river-bottom after the manner of a duck. When it is remembered
that its eyes are kept closed while beneath the water, it becomes
extremely unlikely that the animal should catch such active creatures
as freshwater shrimps except very occasionally. Crowther certainly
mentions shrimps; but he probably refers to crustacea like the curious
and archaic _Anaspides_, which is found in Tasmania among stones on the
river-bottom, and which runs rather than swims.
The food of the platypus must necessarily vary in different places and
at different times of the year, limited as it is to the invertebrate
fauna present in the water at any given spot. It consists of
immature molluscs, aquatic worms, the aquatic larvae of many insects
such as dragon-flies, caddis-flies, may-flies, and the like, the
larvae and perfect insects of groups such as the water-beetles and
water-fleas--which are wholly aquatic--bottom-feeding water-bugs, and
such crustacea as inhabit the bottoms of streams. This food is taken in
with a certain quantity of mud or sand, which, as Bennett has noted,
appears to be absolutely essential for the purpose of mastication. The
living prey is killed while held in the long horny ridges situated in
the anterior part of the mouth-cavity, and is passed rapidly backwards,
being prevented from reaching the gullet by the bulbous hinder end
of the tongue, and directed to one side or other by the tooth-like
projections at the base of the bulb.
I cannot agree with Crowther’s observation that the tail is the first
part of the animal to reach the surface. Apart from the inherent
improbability that so cautious an animal should expose its blind end
first, my observations, both in the open and in a tank in captivity,
show that the tip of the muzzle is always the first part to appear,
followed by the top of the head. The eyes immediately open, and, if
there be no suspicious sight or sound, the rest of the body is allowed
to float towards the surface, beneath which, however, it usually
remains almost submerged. The animal floats in a spread-eagled fashion,
with its webbed hands moving slowly, palms upward, to maintain its
position, and causing the rings of ripples to which Bennett refers.
Semon’s comparison to a plank is not very happy, nor do I concur in
his statement that the animal usually lies motionless at the surface.
Bennett (1860, p. 106) puts it thus:--
“When the fur of the _Ornithorhynchus_ is wet, it has a sordid and
far from attractive appearance, resembling rather a lump of dirty
weeds than any production of the animal kingdom; indeed, were it not
for their paddling motion on the water, these creatures would often
escape observation; for their suppleness and colour, when wet, would
cause them to be regarded only as masses of weeds, which are so often
seen floating about the rivers.”
At the surface the animal chews the results of its catch in a leisurely
manner, its jaws working laterally like those of a cow when chewing
its cud; having swallowed the contents, it dives in search of more. In
diving, the head is first immersed by bending the anterior half of the
body downwards and almost simultaneously humping the back. The head
is then flexed violently against the chest, giving a very powerful
downward thrust comparable with that produced by a crayfish through
the sudden flexure of its abdomen. This carries the body below the
surface, a process which is aided by an upward thrust of the muscular
tail. The webbed fore-paws are used alternately, the web being arched
in the manner described by Crowther; the feet and tail trail behind.
The animal swims in a determined fashion, at a steady but not fast
pace, to the bottom, which is first touched by the tip of the muzzle.
The fore-limbs are now laid back beside the trunk, and the webs are
kept beating upwards, to hold the animal at the bottom. The body is
strongly arched, the sides of the tail curve inwards so as to produce a
concavity of its lower surface, and the end of this concave surface is
applied to the bottom as if helping to keep the platypus down. In this
somewhat constrained position it ‘bobs’ along the bottom of the river,
testing every part with its tactile muzzle. It has every appearance of
having to work hard against a natural tendency of the body to float to
the surface. After two or three minutes it raises its head, relaxes the
tense attitude of its body, immediately begins to float upwards, and
hauls itself to the surface hand over hand by means of the webs of the
fore-paws. If suspicious or frightened, it may merely show enough of
the tip of the muzzle to expose the nostrils, take in a new supply of
air, and dive again immediately. When the animal is undisturbed, the
dive is practically noiseless; but when it is alarmed, there is often a
distinct double splash made by the almost simultaneous strokes of head
and tail, one downward, the other upward.
The swimming motions described above are those employed during
feeding-time. When the platypus is definitely on the move, it swims
fairly rapidly at the surface, and frequently raises its head out of
and parallel with the water, so that it looks rather like a duck. Both
myself and the late Charles M. Hoy have on several occasions noticed
another kind of progression in the water. The naturalist’s way of
collecting platypus is not to shoot it, but to place a bullet from a
heavy rifle beneath it when the animal is floating. The concussion from
the impact is usually sufficient to kill it out-right; but sometimes
it is only temporarily stunned, and, on coming to, makes for the bank,
where it can be easily secured. When a platypus has been temporarily
stunned by concussion, and then recovers, it can almost be declared
that when forging for the bank, it actually crawls along the surface
of the water, for the fore-paws can sometimes be seen clearly above
the surface, which the tail frequently lashes. On such occasions,
two of which I have witnessed, the pace is decidedly fast and noisy,
while the water is beaten and churned considerably by the action. Hoy,
writing to me from Ravenshoe in northern Queensland on September 3,
1920, describes an uninjured male doing much the same thing:--“Saw
male and female evidently copulating, and secured female--left ovary
very much enlarged. Although usually very shy, the male came to the
surface and swam up to within three feet of me, while I was taking
the female from the river. He elevated his head from the surface of
the water, splashing vigorously with his limbs and tail and taking
on a very pugnacious attitude.” It is worth noting here that this
particular male persisted in his charge until he was within three feet
of Hoy, although the latter tried hard to frighten him back by throwing
up his hands. Hoy admitted to me later that he was afraid of being
spurred by the “hissing” ferocious creature. On the strength of this
authentic observation, made in broad daylight, and of others that I
have made at dusk, I am quite convinced that this method of swimming is
also indulged in during nocturnal frolics. Apart from the actions of
the infuriated male encountered by Hoy, platypus cautiously submerge
themselves to the extreme during the daytime; but this is not the case
when darkness sets in, principally because their vision then becomes
acute. The late Geoffrey Smith (1909, p. 124) has observed this mode of
swimming, and writes:--“I was surprised at the extraordinary tameness
of the Platypus, several of which swam quite near the boat with the
whole of their body exposed above the water and shining with a curious
grey appearance in the sunlight.” This occurred at Mount Read, in
north-western Tasmania.
Semon has observed that a platypus which has been shot and killed
invariably floats high out of water. I can substantiate his statement,
and have observed also that the submerged animal has to work
continuously to keep itself down. Just how it manages to float with the
body submerged in the way described above I am not certain, but the
slight motions of the hind limbs and tail probably aid in this act. The
swimming stroke of the fore-paw is outwards, backwards, and upwards,
and ends with the hands palm-upwards against the sides of the body.
When performed slowly and gently, this stroke would serve to pull the
fore-part of the body down in the water. As the limb is thrust forward
again, the resistance of the water keeps the web folded on the palm,
until it is voluntarily extended to begin a new stroke (see Plate 25).
[Illustration: VENTRAL VIEW OF MALE PLATYPUS.
Note upturned palms, also stain on breast, probably due to secretion
from scent-glands.
_Plate 27_]
On land the progress of the platypus is not nearly so happy. The web of
the fore-paw is folded under the palm, and the two limbs of one side
are rotated outwards and forwards together. The nails of the fore-paw
take a grip, and the creature pulls itself forward, going over on its
knuckles as it does so. Meantime the backwardly directed claws of the
foot have taken purchase, and the body is levered forward on the right
limb. Then the limbs of the other side come into play. The result is
a shuffling, sinuous motion, resembling, as I have said before, that of
a heavy-bodied lizard, such as the Blue-tongue (_Tiliqua scincoides_).
Both the trunk and tail drag upon the ground. Considering how clumsy
its method of locomotion is, it is surprising how fast the platypus
can move when it has need of haste. When going at top speed, it can
raise its body almost completely from the ground, as the photograph
reproduced in Plate 26 shows, and can travel on level ground at the
rate of 200 feet per minute (by stop-watch).
The platypus cannot remain for any great length of time in water
without some means of resting, otherwise it will become exhausted and
drown, for it must be remembered that the platypus is a mammal and
resorts to water mainly for its food, after which it must dry its
coat and retire to its burrow for warmth. A freshly-trapped robust
male was placed in an open tank while I leaned over so that it could
clearly see me. The animal immediately dived and, by maintaining upward
pressure with its fore-paws reversed, remained at the bottom for
several periods of six minutes each, with intervals of one minute at
the surface, during which it exposed the tip of its bill as far as the
nostrils. While collecting two specimens of brooding females for the
University of Sydney, and as they had to be killed in the process, I
took the opportunity to ascertain that they survived 5½ and 6 minutes
respectively before drowning in small wire cages. These observations do
not prove that the male can stay under water longer than the female,
as, during a test made midway between breeding seasons, a female
survived for 10 minutes. This is by far the longest period which I have
observed.
The aquatic life of the platypus occupies but a small portion of its
time. Besides feeding and tunnelling, its only other duty would seem
to be that of making its toilet--the rest of its time being spent in
sleep. It performs its toilet, as a rule, while resting on the bank, or
at all events rids itself of most of the moisture from its fur before
going off to continue toilet operations in its resting-burrow. Bennett
(1860, p. 119) gives an account of the operations performed by a
captive which was tethered by means of a cord attached to one leg:--
“After it had wandered some distance up the chain of ponds, feeding
about the shallow water and mud near the margin, it crawled up the
bank, and, lying down on the grass, enjoyed the luxury of scratching
itself and rolling about. In this process of cleaning its skin, the
hind-claws were brought into use--first the claws of one hind leg,
then those of the other; but finding that it could not use the one
to which the string was attached so well as the other, which was
disengaged, after repeated trials it gave up the attempt. The body,
being so capable of contraction, was readily brought within reach of
the hind feet, the head also coming in for its share of the process.
The animal remained for more than an hour cleaning itself, after
which it had a more sleek and glossy appearance than before. Placing
my hand on a part which it was scratching at the time, the claws
passed over it instead of the animal’s body, when I found that it
performed the combing in a remarkably gentle manner. On my attempting
to scratch the place gently, it started away, but not far, and soon
resumed the method of cleaning itself, which I had interrupted.”
From personal experience with platypus in captivity, I am convinced
that Bennett’s tethered specimen was actually dying of shock and
starvation the while he imagined it was enjoying the pleasure of
scratching itself and rolling about.
Bennett also describes the animal as preening its fur with its muzzle,
like a duck. Semon (1894, p. 11) records that on two occasions he saw
duckbills lying in the grass on the river-bank, stretching themselves
and cleaning their fur.
My observations show that the hind-claws play the principal part in
toilet operations, but that the fore-paws are used as well. The animal
squats on its haunches, and by its gymnastic ability is able to bring
almost every part of the body within reach of one or other of the hind
feet. It aids this process in a rather ludicrous way by pulling the
loose skin round into the desired position with the paws, the webs
being extended but not expanded in the action. It also cleans itself
with bill and fore-paws, just as a seal rubs itself with the hairy palm
of its flippers while lolling in calm water. I have seen a wet platypus
sit up and pull its exceptionally loose skin about with its fore-paws,
as if actually massaging itself. The pressure of the broadened claws
against the intervening thin webbing is evidently quite sufficient for
that particular phase of its toilet. In that case the webbing serves
for a rub-down in the same way as a moistened chamois pelt, if nothing
more. Seeing, however, that the fore-claws are used principally for
scratching into solid soil, and that the versatile and oscillating
hands are adapted for grasping, the platypus may readily transform them
into excellent combs by merely palming the webbing, as when burrowing,
walking, running, or climbing, and may use them for combing the parts
which cannot be reached with the hind-claws.
In respect of thorough cleanliness the platypus easily holds its own
among mammals. In person and in dwelling-quarters, even when brooding,
it always exhibits conditions exceptionally tidy. How different is
this monotreme from its only known living relative, the echidna. To
my mind, as regards toilet at least, the contrast is extreme. Every
time I have examined a freshly-caught platypus--wet or dry, young or
old--it was particularly clean in skin, pelage, and external orifices,
such as facial furrows, nostrils, etc. Of course, this may be partly
due to its semi-aquatic nature. Its water-dreading cousin, meanwhile,
is about the dirtiest wanderer afoot. Quite apart from its perpetually
begrimed muzzle and snuffling nostrils, the eyelids of an adult echidna
of either sex are frequently found to be caked with a mixture of earth
and secretions from the eyes, while the skin of the abdomen and the
hair thereon are seldom found to be clean. Again, the temporary pouch
of the female echidna, prior to weaning the occupant, is filthy, and
this condition is certainly not entirely due to milk stains. Obviously,
then, it is a blessing for both that the pouch is not a permanent
feature, otherwise the mother would have to evolve something better
than awkwardly-turned toe-nails and, possibly, a tacky tongue to
complete her so-called toilet. Incidentally, it is fortunate for the
young one that it is transferred, in a lethargic state, to sweeter
quarters before attaining sufficient sense to observe its surroundings.
Though I have often disturbed platypus on river-banks, I have never
seen them engaged in performing their toilet in the open. They resort,
as a rule, to flat ledges under projecting roots, or to similar cover;
these places, judging from the tracks leading to them, and from the way
in which they are flattened down as if through long usage, would seem
to serve as toilet tables of a comparatively permanent nature--that is
to say, regular resorts of a given animal while it is in any particular
locality. In such a place the platypus, secure from observation, and
able to slip quietly into the water at the slightest alarm, removes
the water from its fur, and reduces the latter to that condition of
sleekness which is so essential to its well-being. As with most wild
animals, the first sign of ill-health is the neglect of toilet, and
this neglect in the case of _Ornithorhynchus_ is rapidly followed by
death. I have frequently noticed that sickly and enfeebled animals
will attempt to perform the toilet motions, but are so little able to
correlate their activities that the claws pass helplessly up and down
without touching the body at all. In this condition they take no heed
of man’s presence, being practically unconscious. It should also be
noted that the feet are used for scratching the body while the platypus
is floating at the surface; but this is probably due to the irritation
caused by parasites. _Ornithorhynchus_, although flealess, shares with
a very few animals the rather doubtful distinction of having a tick,
_Ixodes ornithorhynchi_, all to itself.
[Illustration: FEMALE PLATYPUS, TAKEN DIRECTLY FROM NEST AND PERSUADED
TO ADOPT SLEEPING POSITION.
This same position is used in the nest during incubation and nursing of
the very young.
_Plate 28_]
Its toilet completed, the animal retires to its resting-burrow
to sleep. Between this burrow and the nesting-burrow of the
breeding-season a sharp distinction must be drawn. Existing accounts
of the habits of the animal assume that the nesting-burrow of the
breeding-season is the home of the platypus all the year round. Nothing
could be farther from the truth. The complicated nesting-burrow is
constructed by a single female for the purpose of laying her eggs and
rearing her young, and is not resorted to by any other individual.
Resting-burrows are, however, made by both males and females at all
times of year. They are usually semicircular excavations under the
roots of large red-gum trees and the entrance at each end is concealed
by overhanging ledges, generally in the neighbourhood of the ‘toilet
tables.’ The diameter of these tunnels is irregular, but always much
greater than that of the nesting-burrows; the sleeping-chambers,
from one to three in number, are simply enlargements of the burrow,
containing no sign whatever of nesting-material or bedding. These
burrows appear to be either purely male quarters or purely female
quarters, the sexes not being found together in them. At most I have
found two males occupying a single burrow.
When the animals are on satisfactory feeding-grounds, such burrows
appear to be used regularly by the same individuals. But when they are
forced by flood or freshes to move elsewhere, it becomes necessary to
find new quarters. During these times platypus are sometimes captured
in hollow logs or, in districts where alluvial mining is carried on, in
sluice-boxes. Under stress the animal appears to make use of any kind
of cover available. The males evidently make their own camping-burrows,
as they are frequently found with the bald patch near the end of
the tail. This is caused, as in the case of the female, by plugging
off undesirable subways, etc. Burrows used by males may also be
distinguished from breeding-burrows by a foxy odour which is compared
by Mackenzie and Owen (1919, p. 12) to that of an onion. The odour is
caused by the secretion of the scent-glands, which are situated at the
base of the neck, just in front of the shoulder (see Plate 27).
Although, except during the breeding-season, platypus may be considered
solitary animals, they are occasionally found in company for short
periods, when forced by seasonal conditions to migrate. The greatest
number that I have observed at the same time was four, and they did
not appear to be consorting with one another, but simply feeding
about quite independently. On one occasion I unearthed two adult males
which were camping contentedly together in the one burrow. On another
occasion I secured two males in a “turret trap” which had been set in
the early morning for only an hour and a half. On a third occasion
three males were trapped in one night, either while leaving or entering
a camping-bank beneath a giant red-gum--a “buck barracks,” as I have
since named the haunt.
Although Bennett has made the suggestion that _Ornithorhynchus_
hibernates, my investigations do not bear him out. In the New England
district of New South Wales the pairing season commences in July, which
is the midwinter month on those cold highlands. The platypus lives an
active life the whole year through, and eats prodigious quantities of
food.
The thing one first notices in a living platypus is its extraordinarily
restless activity. It is far more difficult to hold than any other
animal of its size with which I am familiar, not so much on account of
the actual strength and violence of its struggles, but because of its
persistence in them. Bennett frequently remarks on the way in which
the “looseness of its integuments” renders it difficult to hold. He
refers to the skin and its underlying muscle-layer (the _panniculus
carnosus_), which, in most mammals a very thin sheet, is in the
platypus a thick muscular jacket, with slits through which the limbs
and tail project and with numerous strong slips attaching it to various
parts (see Plate 10). The animal seems to be able to slip its body
through this loose overlying sheet in an uncanny invertebrate fashion,
struggling forward for a time, and then, when it finds its progress
prevented, suddenly changing its direction and slipping backwards out
of one’s hands. At the same time all four powerful limbs are brought
into play, and the head, flexed downwards by strong depressor muscles,
also helps in the struggle. The only way in which the animal can be
held safely is by grasping the scruff of the neck with the left hand
and the tail with the right. While most animals after a time resign
themselves to the inevitable, the platypus continues to struggle until
exhausted, unless one is fully acquainted with its ways and coaxes it
(see Plate 28).
Many observers have borne witness to the nervous temperament and
restless activity of the animal in captivity. Three individuals which
were forwarded by me at various times to the Department of Zoology at
the University of Sydney, in order that some observations might be
made, were all very impatient of the excitement and fuss of constant
inspection and handling, and none lived longer than seventy-two hours.
As the animals are easily capable of standing fasts for much longer
periods, death would appear to have been due to nervous exhaustion, and
certainly not to inanition--although, it is true, they took very little
of the food that was provided for them.
It does not seem that the platypus displays anything of that affection
for its mate which is so characteristic of the behaviour of birds and
higher mammals. The period during which the mated pair are together
is short, and I have no evidence that the male takes any further
interest in the female and its young when once impregnation has been
accomplished. The solitary observation of Hoy, quoted earlier--which
might be taken to mean that the male charged in defence of his
mate--is equally open to another, and, it seems to me, a more natural
interpretation. Anger at the actual deprivation may have played a
greater part than affection, for the actions were those of an angry
beast. Moreover, since the occurrence took place in broad daylight,
it is possible that the animal had only a very incomplete conception
of what was going on. Nevertheless it remains to the credit of this
particular male, that he did not dive and disappear after the report of
the rifle, and the impact of the bullet close to him in the water.
Nor would the female platypus seem to show any actual affection for
her offspring. She uses great cunning to keep them safe, and sees to
their physical well-being with meticulous care, reducing herself to
a state of emaciation and exhaustion in the process. But she makes
no attempt to stay by and defend them when a burrow is opened up,
her chief anxiety being to escape. I have never known a female in the
burrow to show fight, or attempt resistance of any kind. Yet, even so,
she shows signs of agitation, which is more than some marsupials do.
When one tears the young from the back of a koala (_Phascolaretos_) for
instance, the mother, after one vacant look in the direction of her
puling infant, goes on calmly chewing gum-leaves.
The male platypus sometimes proves both pugnacious and aggressive. One
which I was using for photographic purposes showed a great dislike
of the process and deliberately charged and bit me on the arm and
fingers. I compare the bite--which was made with the anterior pairs of
horny ridges--with that of a gander, and it was sufficiently severe
to cause me to take precautions against further attacks. Since then I
have experienced bites from both male and female platypus which were
deliberately roused for the purpose.
How far it is permissible to attribute to intelligence habits of
wariness and cunning which have become what we are pleased to call
instinctive is a moot point. The wary ways of the platypus have been
described more than once, and there is no need to repeat them here. We
may, however, assume that these ways, though they are proving useful
against the onslaughts of European man, were used before his arrival.