Friday, 26 February 2010

Can you bear it?

The family Ursidae is one of the most instantly recognisable of the carnivoran families: there are (arguably) eight species alive today, split into three subfamilies: Tremarctinae, consisting of the extinct short-faced bears and the only South American member of the family, the spectacled bear (Tremarctos ornatus); Ailuropodinae, containing only the extant giant panda (Ailuropoda melanoleuca) and extinct relatives; and the Ursinae, containing the remaining three extant genera. It is this subfamily that this post is about.



Skull of Asiatic black bear
Ursus thibetanus (Georges Cuvier, 1823)
Ursidae; Carnivora; Mammalia; Chordata
Galerie de Anatomie Comparée, Paris, France
January 2010

The Asiatic black bear is distributed across much of southern and eastern Asia, from Iran to Japan, in temperate climates. It is a shaggy-furred animal, usually marked with a wide crescent-shaped creamy-white patch on its chest, giving it the alternative name of 'moon bear'. It is placed in the subgenus Selenarctos, which has often been given generic status. Another one of its distinctive features is the small rounded ears, giving it a very teddy bear-like look. It is a herbivorous animal, like most other bears, mostly eating plant and animal matter much smaller than itself. Despite this, they are of course still bears, and are capable of killing large ungulates up to the size of a water buffalo. It goes without saying, therefore, that they could easily kill a human. An unusual threat to the Asiatic black bear's survival comes from deep within its viscera: the bile is valued in eastern medicine, and bears in China and Vietnam are often hooked up to a tap in order to obtain the substance without killing the animal. That is the intention: of course, if the catheter site becomes infected, the bear would die of horrific secondary infection anyway.



American black bear skull
Ursus americanus (Pallas, 1780)
Ursidae; Carnivora; Mammalia; Chordata
Galerie de Anatomie Comparée, Paris, France
January 2010

This is a familiar bear to most people, especially as one of its alteregos: Winnie the Pooh was an American black bear, as is the traditional teddy bear. Like the teddy bear, the American black bear comes in a variety of colours: as well as the typical black, there are brown, cinnamon, blue, cream and white 'black' bears, some of which are restricted to certain areas. The Kermode bear, also known as the spirit bear, is one of those pure white animals, found only in certain parts of British Columbia, western Canada. The bear, in all its colour morphs, is distributed throughout North America from Canada to Mexico, and is much more common and widespread than its larger relative, the grizzly.



Grizzly bear skull
Ursus arctos horribilis (Ord, 1815)
Ursidae; Carnivora; Mammalia; Chordata
Galerie de Anatomie Comparée, Paris, France
January 2010

The grizzly is the typical North American representative of the brown bear species. In general, any brown bear from continental North America, apart from parts of Alaska, will be known as a grizzly. In Alaska and across Eurasia, they are known as brown bears. It's probably the most well known of the bears, and there isn't much to say about it that isn't already common knowledge. Grizzly bears are most likely the direct ancestor of the polar bear: they have hybridized successfully, even in the wild where the ranges of both species overlap.



European brown bear
Ursus arctos arctos Linnaeus, 1758
Ursidae; Carnivora; Mammalia; Chordata
Whipsnade Wild Animal Park
April 2009

Brown bears differ in size across their range, the smallest races being from southwest Asia (U. a. syriacus) and Europe (U. a. arctos), the largest from Alaska (U. a. gyas and U. a. middendorffii). That said, the European bears are still bloody huge!



Polar bear skull
Ursus maritimus Phipps, 1774
Ursidae; Carnivora; Mammalia; Chordata
Galerie de Anatomie Comparée, Paris, France
January 2010

Polar bears are the most carnivorous of the ursines: their diet is almost exclusively meat-based, being mostly seals and other marine mammals. They will of course opportunistically take other items, like fish and berries, but these make up an infinitesimal part of the diet. It is placed in the subgenus Thalarctos, but that seems unlikely, seeing that it appears closer to U. arctos than other members of Ursus.



Female polar bear, 'Mercedes'
Edinburgh Zoo
June 2005

The animal in the above picture was moved last year, from Edinburgh Zoo to the more suitable Highland Wildlife Park further north in Scotland, and remains the only captive polar bear in the UK.



Sloth bear skull
Melursus ursinus (Shaw, 1791)
Ursidae; Carnivora; Mammalia; Chordata
Galerie de Anatomie Comparée, Paris, France
January 2010

If you read The Jungle Book by Rudyard Kipling, or watched its Disney adaptation, as a child, you will instantly remember Baloo, the friendly bear. Seeing as the story was set in India (I always hated the fact there was an Indonesian orang-utan in an Indian forest in the film!), it's most likely that the bear was a sloth bear. These bears are the most widespread ursine in the Indian subcontinent, also being found in Sri Lanka. When first described by George Shaw in 1791, he placed it in the genus Bradypus. Its resemblance to a sloth was so influential that he essentially named it 'bear-like sloth' instead of the other way around. We now know better, that it belongs in its own genus, Melursus, within the Ursidae.



Sri Lankan race of the sloth bear
Melursus ursinus inornatus Pucheran, 1855
Ursidae; Carnivora; Mammalia; Chordata
London Zoo
April 2007

Like the Asiatic black bear, the sloth bear has a crescent-shaped mark on its chest, but it can be differentiated based on its much shaggier fur and prehensile lips. It uses these to create a vacuum with which it uses to such termites out of mounds. These are its most usual food: those claws come in handy for breaking open the mounds, as well as defending themselves from tigers, leopards, other bears and humans too.



Skull of young Bornean sun bear
Helarctos malayanus euryspilus Horsfield, 1825
Ursidae; Carnivora; Mammalia; Chordata
Galerie de Anatomie Comparée, Paris, France
January 2010

The sun bear is the smallest of the ursines, being only 4 feet (120 cm) in length as an adult. It is so called because of the yellow to orange chest patch, contrasting nicely with the moon bear. Despite its size, it is a feisty and brave creature, breaking open beehives with its long curved claws, inserting its monstrously long tongue into the nest to extract larvae and honey, probably its favourite food. A sun bear was famously kept as a pet by Sir Stamford Raffles, founder of both Singapore and the Zoological Society of London. His pet bear would often sit at the same dinner table, also shared by a clouded leopard (!)



Ventral view of a sun bear skull
Ursidae; Carnivora; Mammalia; Chordata
Galerie de Anatomie Comparée, Paris, France
January 2010

In this wonderful view of a sun bear skull, you can see some of the features that make carnivorans what they are. Although not incredibly well developed in the bears, having reverted to an omnivorous dentition, the upper carnassial teeth can be seen. These are the large teeth near the centre of the photo, unique to carnivorans, ideal for cutting meat. Just watch a cat chew its meat and you'll see the carnassials at work. The auditory bullae, the round knobs of bone towards the rear of the skull, are where the inner ear lives, and the structure of these differs from family to family among the carnivorans.

That's it for the extant ursines: I will continue with three extinct European species of Ursus: U. fossilis, U. deningeri and U. spelaeus.

4 comments:

Glendon Mellow said...

Amazing how round those first three skulls look! Needed to say that.

Mo Hassan said...

yeah, there is a certain roundness to them. Of course it might just be the angle.

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Anonymous said...

The juvie bear's skull almost reminds me of a canid's in a way.