Koala—The bear that isn’t!
Photo by Cody Pope. License: CC-BY-SA-2.5
According to his diary of 1802, written while exploring the Nepean River in the Camden area south-west of Sydney, Australia, Ensign Francis Barrallier of the New South Wales Corps traded two spears and a tomahawk for the feet of a dismembered mammal known to the local Aborigines as the ‘colo’. These were sent to the governor of the fledgling colony, Governor King, in a bottle of brandy, but there appears to be no further record of these specimens, nor even formal recognition of the spirit in which they were sent! The following year he was more successful and sent a live animal to the governor.
This animal had not been seen by Captain Cook’s party at Botany Bay in 1770 because of its forest preference, and went unreported for a decade after the First Fleet had arrived at Sydney Cove in 1788. John Price, a young free servant of the governor, Captain John Hunter, made the earliest reported sighting south-west of Sydney. In his journal of 1798 he wrote: ‘There is another animal which the natives call a Cullewine, which much resembles the sloths of America.’
Cullewine, koolewong, colo, colah, koolah, and koala appear as the Aboriginal names in the various dialects of eastern New South Wales, although these recorded names are undoubtedly complicated by problems of transliteration and printers’ errors.
The first serious description, written by Lieutenant-Governor Colonel William Paterson, was published in London in 1808. Paterson stated that the native name was ‘koala wombat’, which later became koala. Later its general appearance gave rise to the misleading name of ‘native bear’. This attractive and unique animal is in fact a marsupial, or pouch-carrying mammal, like another famous Australian, the kangaroo. The koala’s genus name is Phascolarctos, from the Greek meaning a leather bag (pouch) and a bear, while its species name is cinereus (ashy), because of the grey colouring of the original specimens.
Because of the special nature of the koala’s diet of eucalypt leaves, few zoos outside Australia are able to successfully provide for koalas, the San Diego Zoo (USA) being one of the few.
Adult koalas weigh between four and 15 kilograms (about nine and 33 pounds respectively). Their length is 600-800 millimetres (approximately 24-31 inches); a tail is virtually absent (it has a rudimentary but muscular stump). Their dense, woolly fur effectively protects koalas in cold weather, and they survive high temperatures by panting. The large head, big, hairy ears, and large nose produce a comical and appealing appearance.
The koala is highly specialized for its existence in trees. Long curved arms and sharp claws give it the ability to hold on to and scramble rapidly up large tree trunks, aided by the vice-like grip of its hands. These have the first two fingers opposed to the last three, like the possums, but in an even more specialized way. The first toe on the rear feet lacks the sharp claw of the other four toes, but is opposed to them and is used in a grasping thumb-like way on smaller branches. On large smooth trunks the widespread claws of the koala dig into the bark like a grapnel hook.
Over its range from the tropics to the cool-temperate regions of eastern Australia, the koala is limited to areas where there are acceptable food trees. Only about 12 species of eucalypts with high oil contents are suitable, although it seems certain the koala needs a varied diet selected from among these. This may be because some, such as the Manna Gum, produce poisonous prussic acid in new leaves at certain times. Many eucalypts and non-eucalypts may contribute to the diet and there are marked local and seasonal preferences. As eucalypt leaves have a high water content, the koala normally does not need to drink. Actually, it appears that the name ‘koala’ is derived from a word meaning ‘no drink’ formerly used by Aborigines near Sydney. [Web Editor’s note added 17 October, 2013: We are aware that other plants have a much higher water content than eucalyptus leaves, for example, lettuce. Also, koalas have been known in some circumstances to drink water straight from a bottle, as shown in the famous case of ‘Sam the Koala’ and the February 2009 Victorian bushfires.]
Eucalypt leaves contain high fibre and low protein. They contain strong smelling oils, phenolic compounds and sometimes cyanide precursors which make them unpalatable or even poisonous to most mammals. To cope with this diet, the koala has numerous specialization’s, most notably a large caecum, opening off the intestine. This caecum measures 1.8 to 2.5 metres (six to eight feet) in length, proportionally longer than in any other mammal, and in it microbial fermentation takes place, aiding digestion of the bulky, fibrous eucalypt leaves. Oils and phenolic compounds are detoxified in the liver and leaves containing cyanide precursors are probably avoided. There are no grounds for the widespread belief that eucalyptus oils intoxicate koalas, rendering them lethargic.
Eating, Sleeping, and …
A koala consumes daily (on average) more than a kilogram (two and a half pounds) of foliage. Early reports suggested that, like the wombat, the koala sometimes ate roots or ground herbage while crossing from one tree to another. It now seems more likely that an animal may occasionally lick up earth (soil and gravel) to adjust deficiencies of minerals, such as bone making calcium, in its diet of leaves. Koalas when resting burn up energy at only three quarters of the rate of most other marsupials.
Wikimedia commons/Mike R
The koala moves about and feeds at night with a peak of activity just after sunset, although it is perhaps less nocturnal than many marsupials. While it sleeps in a fork of a tree during the greater part of the day, it is liable to wake up at any time and start feeding on nearby leaves. The slothful appearance of the koala is deceptive; it can move very rapidly through the branches, and can jump a metre (three feet) or so from one branch to another. The koala may also travel for some distance on the ground.
The precise habits of the koala in the wild, especially its breeding habits, are still not well known. It has long been considered a solitary animal, members of a population usually being evenly distributed in a changing pattern through the available forest. However, recent observations of koala populations suggest that the males often have two or three females fairly close by, forming a kind of harem. This may occur, of course, only during the mating season.
Males are larger than females, and males have a large sternal gland which is used in the breeding season for scent marking; the male grasps a tree trunk and rubs his chest up and down against it. The male’s behaviour and loud bellowing seem to be involved in the spatial separation of mature males and in their competition for mates. At night, in areas where they are numerous, the grunting, pig-like sounds of koalas can be heard. When alarmed or distressed they make a continuous loud wailing sound. Koalas are, however, generally inoffensive. Not surprisingly, they have a characteristic eucalyptus-like odour.
Mating takes place in spring and summer. At these times the males fight fiercely, their loud angry growls echoing through the night. Most mature females produce one young (rarely twins) each year, although some authorities suggest they only breed as a rule every second year.
Erik Veland. License: CC-BY-SA 3.0
The Pouch of the Mother
The gestation period for the koala embryo is thought to be about 35 days. The young is barely two centimetres (three-quarters of an inch) long and weighs little more than two ping pong balls at birth (less than 5.5 grams or 0.2 ounces). Like other marsupials, the forelimbs are already strongly developed for clinging to the mother’s fur on the immediate and unaided journey to the pouch, a slow wriggling crawl guided by instinct!
Of particular interest is the fact that the female koala’s pouch opens backwards, that is, towards the rear. This unusual feature is shared only with wombats, bandicoots and thylacines (Tasmanian tigers). On the other hand, kangaroos and possums all have pouches which open forwards (or upwards). Such features in animals are generally closely related to their habits. But in the case of the koala and the wombat, the habits are totally different. It is obvious that the rearward-facing pouch of the wombat was designed to overcome the problem of the pouch’s becoming filled with earth when the animal is burrowing. It is not so easy to appreciate the value of such an upside down pouch to a tree-climbing animal like the koala. All the possums that share the koala’s arboreal habits have a deep forward-facing pouch, which forms a safe repository for the young while the mother is climbing. The evolutionist who looks for common ancestry relationships finds this baffling.
Once inside its mother’s pouch, the new-born koala attaches itself to one of its mother’s two teats. It remains in the pouch suckling on its mother’s milk until it is about six or seven months old. It is then about 18 centimetres (seven inches) long and is well covered with fur. It continues to use the pouch for about two months more, making increasingly frequent excursions clinging to its mother’s back or chest. From then until an age of about a year, the young koala continues to be carried on its mother’s back, or hugs closely to her when resting or cold. At such times this twosome presents a most attractive and appealing sight.
Ignacio Catalina. License: CC-BY-SA 3.0
In the last few months of pouch life, weaning of the young from its mother’s milk to gum leaves commences. This weaning process involves a drastic adjustment to digestive processes, which is initiated by feeding on a most unusual transitional food. Most researchers have thought this consisted of soft pellets or droppings of partly digested gum leaves which have passed through the mother’s caecum and digestive tract, but recent observations suggest that the young is actually feeding on a soft green fluid called ‘pap’ assumed to be derived from the contents of the caecum and produced with the normal droppings by the mother. No other animal is known to be weaned in this way. This is thought to prime the caecum of the young koala with the bacteria essential for its function, but it may also provide a rich supply of bacterial protein for accelerated growth.
At 12 months the young koala is fully weaned and independent of its mother. By 18 months it has usually moved away from the area where it was born.
Females become sexually mature at the age of two years, males at three to four years. There is little information on longevity in the wild, but captive animals have lived for more than 15 years, and some authorities suggest the maximum lifespan is about 20 years.
Competition and Survival
Australia’s first settlers, the Aborigines, frequently used the koala for food, but apart from that risk it probably had few natural predators. However, periods of drought may often result in the death of many koalas.
The coming of white settlement, with the subsequent clearing of land and the increase in the frequency of bushfires, plus shooting for its highly prized fur, brought the koala to the verge of extinction earlier this century. It is now fully protected, large tracts of eucalypt forests are being preserved, and a vigorous research program is under way to reduce further threats to its survival. These include some new diseases, one of them sexually transmitted.
Ancestors and Relatives
Photo by DAVID ILIFF. License: CC-BY-SA 3.0
But what of the origin of the koala? The evolutionist who looks for common ancestry with the koala’s marsupial relatives remains baffled. So adept is the koala at climbing, that faced with the problem of establishing some kind of relationship for this animal with other marsupials, it was grouped with the possums. Nowadays, however, the koala is considered to have a closer relationship with the wombat than with the possum, because of certain similarities in anatomy, blood proteins, and chromosomes. But even these features present contradictions. The hand structure, teeth arrangement, and leaf diet are somewhat similar to those of the ring-tail possum, but the absence of an obvious tail in the koala (like the sloth and lords femur) is one stumbling block in any scheme to classify it with the possums.
Evolutionary zoologists are forced into all kinds of hypotheses to explain the koala’s possession of possum-like habits, feet, teeth, and diet, and wombat-like pouch and rudimentary tail. They suggest that at some stage a common ancestral stock of both koala and wombat might have lived in trees. Perhaps because they grew too big for the tree-hollows in which most tree dwelling animals shelter, these ancestors at some point came down to the ground and adopted at least a partly terrestrial existence losing whatever tail they once had. Then, perhaps because of predator pressure, one branch of these heavy animals might have taken to burrowing while evolving powerful digging claws. The other branch could have gone back up the trees, its limbs and claws becoming stronger to compensate for its long-lost tail.
What is the evidence for such flights of fancy? To quote Australia’s Professor Michael Archer, vertebrate paleontologist at the University of New South Wales:
‘It is somewhat premature to attempt an analysis of evolution in koalas, in part because very little of the important fossil record is known and what is known consists of only a few teeth, and in part because much of the record that is represented is only just now being analyzed.’ (Archer, 1978, p. 20)
However, even though that analysis is now well advanced, the picture hasn’t changed. Unfortunately for the evolutionist, teeth are the only common denominator of all the koala-like fossils known, and some are only known from single molars.
So the koala is really in a class of its own. The oldest known fossil fragments, various upper and lower teeth, are clearly those of a koala. These scant remains supposedly date back to Middle Miocene times, supposedly about 15 million years ago, according to conventional geologic dating. Between these few teeth found at Ngapakaldi in South Australia, and the koala we have in its entirety today, is a fossil record that consists merely of 10 teeth! Endless comparisons between these teeth hardly amount to any story of evolutionary development, merely variation within a distinct class of creature, the koala and his extinct relatives.
Any notion of the origin of the koala based on comparison of these few scant remains with other teeth of mammals in the fossil record is merely a matter of wild speculation and an evolutionary leap of faith. How to obtain the various unique structures of the koala from the so-called ancestral types, each intermediate stage being fully functional and better adapted than its preceding ancestral form, stretches the imagination beyond limit.
Aconcagua. GFDL, CC-BY-SA-3.0
The Creator God in the first week of history created every kind of creature to reproduce after its kind. The koala displays all the evidence of planned, purposeful design at the hand of a Master Designer.
Chance random evolutionary processes cannot even begin to explain the development of the extraordinarily long caecum (like that of a horse!) in the koala’s digestive tract that uniquely equips it to cope with its eucalyptus leaf diet. And then there is the unique combination of toes, fingers and claws on feet and hands that enables the koala to climb its favourite gum tree.
Likewise, the fossil evidence, what there is of it, gives no indication that koalas have ever been other than koalas. No, the evidence confirms that the koala was fully developed and functional, right from the start, perfectly designed by the Creator, just as Genesis says.
As with the kangaroo, how does the hairless new-born koala manage to crawl to its mother’s pouch across her fur? What of the mother’s pouch that opens rearward? Could all this develop by chance random evolution? What kind of intermediate pouches existed? Might they have opened at both ends? Surely a forward-opening pouch would be better suited to the koala’s tree climbing habits? Obviously, however, this reversed security cradle presents no predicament for the infant koala, since none has been observed falling from the care of its mother perched in the lofty heights of the Australian bushland.
No, the all-knowing and wise Creator designed this lovable Australian to be what he is: unique! The complexity and beauty of God’s creatures only serve to glorify Him as their Creator.
- Archer, M., 1978. ‘Koalas (Phascolarctids) and their significance m marsupial evolution.’ In: ‘The Koala’: Proceedings of the Taronga Symposium on Koala Biology, Management and Medicine, E.J. Bergin (ed.), Zoological Parks Board of NSW, pp. 20–28.
- Archer, M., 1984. ‘On the importance Of being a Koala: In: Vertebrate Zoo geography and Evolution in Australasia, M. Archer and G. Clayton (eds), Hesperian Press, pp. 809–815.
- Lee, A. K., 1988. ‘Life histories of marsupials, with particular reference to the life history of the koalas’ In: Australian Wildlife, Proceedings of a Refresher course by the Post-Graduate Foundation in veterinary science, The University of Sydney, pp. 613–621.
- Lyne, A. G., 1973. ‘The Koala’ Australia’s Wildlife Heritage, vol. 2(25), pp. 769–777.
- Martin, R. W., 1983. ‘Koala.’ In: The Australian Museum Complete Book on Australian Mammal (The National Photographic Index of Australian Wildlife), R. Strahan (ed.), Angus and Robertson Publishers, Sydney, pp. 112–114.
- Ride, w. D. L., 1970. A Guide to the Native Mammal of Australia, Oxford university Press, Melbourne, pp. 88–90.
- Strahan, R., 1978. ‘What is a Koala?’ In: ‘The Koala’: Proceedings of the Taronga Symposium on Koala Biology, Management and Medicine, P. J. Bergin (ed.) ‘Zoological Parks Board of NSW’, pp. 3–19.
- Troughton, E., 1973. Furred Animals of Australia, Angus and Robertson Publishers, Sydney, pp. 112–115.
Sensational article. An absolute treat!
Love the pun in the first paragraph. Another interesting thing about the koala is its extra thick hide that is handy for all the tree sitting, nice touch by the designer.
Koalas often look relaxed and sleepy but in no way are they slothful. About 2005, in mid summer on Raymond Island Victoria Australia, I watched two koalas playing. They spent at least 10 minutes running up a tree to about 1 to 1.2 metres (3-4 feet) height, jumping to the ground, and repeating the process one after the other with minor variations. I thought I'd video the whole performance and was devastated when I discovered that the camera was on standby rather than recording.
Like Marty S, I appreciated the play on words in the first paragraph, which shows that CMI's contributors have not only undoubted, great insight and knowledge of true science, but a sense of humour, too.
One well-known, Sydney-based minister once argued online with me that God couldn't have created the koala because God wouldn't have put its pouch "upside down". It must have been, he proudly and arrogantly proclaimed on his church's discussion board, evolution.
Apart from his complete lack of faith in God's ability to design properly, I also questioned him as to how many koalas he had seen falling out of their mothers' pouches while in trees. This armchair naturalist never replied.
This oddity of mystical belief was no isolated thought bubble. Another from this very respectable church proclaimed that evolution could have happened by God directing gamma rays from far away galaxies to create the exact mutations that allowed evolution to occur over billions of years.
As I said, this denomination is a leading light in Sydney, yet its ministers routinely trot out the most fabulous fairy tales that one might expect to read to a four year old, not to Christian adults who should be off milk and well on to solid food.
Marc, well said. One wonders whether said church leaders would ever deign to read Practical pouches--and realize the implications.
A 'forwards' facing koala pouch could soon fill with debris rubbed into it from the tree being climbed. Koalas' progress across the ground would also invite debris into a forward facing pouch, it being so close to the ground.
Also, this piece from the Koala Foundation
Do Koalas have a backward-facing pouch?
The pouch is actually situated in the centre of the female's abdomen and the opening faces straight outwards, rather than backwards. However, the pouch opening is towards the bottom of the pouch, so when the joey is larger and puts its head out of the pouch it can appear that the pouch faces backwards.