Physical characteristics Bear

bears include massive extant terrestrial members of order carnivora. polar bears weigh 1,600 lb (730 kg). smallest sun bears of asia, weigh 150 lb (68 kg). body weight varies throughout year in bears of temperate , arctic climates, build fat reserves in summer , autumn , lose weight during winter. head-and-body length can range 150 cm (59 in) in sun bears 244 cm (96 in) in polar bears.

morphology

unlike other carnivora, bears have plantigrade feet. drawing richard owen, 1866

bears bulky , robust animals short tails. sexually dimorphic regard size, males typically being larger. larger species tend show increased levels of sexual dimorphism in comparison smaller species. relying on strength rather speed, bears have relatively short limbs thick bones support bulk. shoulder blades , pelvis correspondingly massive. limbs straighter of big cats there no need them flex in same way due differences in gait. strong forelimbs used catch prey, excavate dens, dig out burrowing animals, turn on rocks , logs locate prey, , club large creatures.

despite being quadrupeds, bears can stand , sit humans do.

unlike other land carnivorans, bears plantigrade. distribute weight toward hind feet, makes them lumbering when walk. capable of bursts of speed tire, , result rely on ambush rather chase. bears can stand on hind feet , sit straight remarkable balance. front paws flexible enough grasp fruit , leaves. bears non-retractable claws used digging, climbing, tearing, , catching prey. claws on front feet larger on , may hindrance when climbing trees; black bears arboreal of bears, , have shortest claws. pandas unique in having bony extension on wrist of front feet acts thumb, , used gripping bamboo shoots animals feed.

most mammals have agouti hair, each individual hair shaft having bands of colour corresponding 2 different types of melanin pigment. bears have single type of melanin , hairs have single colour throughout length, apart tip different shade. coat consists of long guard hairs, form protective shaggy covering, , short dense hairs form insulating layer trapping air close skin. shaggy coat helps maintain body heat during winter hibernation , shed in spring leaving shorter summer coat. polar bears have hollow, translucent guard hairs gain heat sun , conduct dark-coloured skin below. have thick layer of blubber insulation, , soles of feet have dense pad of fur. other bold black-and-white pelage of panda, bears tend uniform in colour, although species may have markings on chest or face.

bears have small rounded ears minimise heat loss, neither hearing or sight particularly acute. unlike many other carnivorans have colour vision, perhaps them distinguish ripe nuts , fruits. unique among carnivorans in not having touch-sensitive whiskers on muzzle; however, have excellent sense of smell, better of dog, or possibly other mammal. use smell signalling each other (either warn off rivals or detect mates) , finding food. smell principal sense used bears locate of food, , have excellent memories helps them relocate places have found food before.

sloth bear skull

the skulls of bears massive, providing anchorage powerful masseter , temporal jaw muscles. canine teeth large used display, , molar teeth flat , crushing. unlike other members of carnivora, bears have relatively undeveloped carnassial teeth, , teeth adapted diet includes significant amount of vegetable matter. considerable variation occurs in dental formula within given species. may indicate bears still in process of evolving meat-eating diet predominantly herbivorous one. polar bears appear have secondarily re-evolved carnassial-like cheek teeth, diets have switched towards carnivory. sloth bears lack lower central incisors , use protusible lips sucking termites on feed. general dental formula living bears is: 3.1.2–4.23.1.2–4.3. structure of larynx of bears appears basal of caniforms. possess air pouches connected pharynx may amplify vocalisations.

bears have simple digestive system typical carnivorans, single stomach, short undifferentiated intestines , no cecum. herbivorous giant panda still has digestive system of carnivore, carnivore-specific genes. ability digest cellulose ascribed microbes in gut. bears must spend of time feeding in order gain enough nutrition foliage. panda, in particular, spends 12–15 hours day feeding.

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