《北极熊英文介绍》PPT课件.ppt

The largest terrestrial carnivorous animal,Polar bear,some pictures about Polar bear,The polar bear is a bear native largely within the Arctic Circle encompassing（围绕，包围;）the Arctic Ocean,its surrounding seas and surrounding land masses.It is the worlds largest land carnivore（食肉动物）and also the largest bear,Polar bearsIn its existent space,it is the topmost food chain.It has thick fat and hair to stay warm,its white appearance on white snow is good protective coloration,and it can on land and sea,so it can catch food in the arctic in this extremely harsh（严酷的）climate.,Ecological role,The polar bear is theapex predator（顶端食肉动物）within its range.Several animal species,particularlyArctic FoxesandGlaucous Gulls,routinely scavenge（清除）polar bear kills.The relationship between ringed seals（环斑海豹）and polar bears is so close that the abundance of ringed seals in some areas appears to regulate（调节）the density（密度）of polar bears,while polar bear predation in turn regulates density and reproductive success of ringed seals.Theevolutionary pressureof polar bear predation on seals probably accounts for some significant differences between Arctic and Antarctic seals.,Because polar bears play an important role in Arctic environment,scientists feel that polar bear can be a good indicator of the health of Arctic environment.So,we can say that by protecting polar bears,we are protecting the whole Arctic ecosystem.,Global warming has an impact on the ice.,The ice is melting quickly in north and south pole.And that have a bad influence on polar bears.Due to the global warming,Arctic ice began to melt,the polar bears home has been destroyed,the prey is also a corresponding reduction in,Polar bears are in danger,we must take measures to protect the kind of beautiful and lovely animal.Because it is the treasure of nature.,Physical character,The polar bears claws are short and stocky.,the teeth are larger and sharper,Polar bear fur consists of dense under fur and guard hairs.,nose,Appearance,small head,small ears and round neck long,wide,foot and leg and palm are hirsutegood swimmerblack skin,Habitat,Marine mammal(because it spends many months of the year at sea).Arctic ring of life,Hunting and Diet,The most carnivorous member of the bear family(most of its diet consists ofringedand bearded seals)Excellent sense of smellRinged and bearded sealswild foods and plants,The polar bears most common hunting method is calledstill-hunting.,The bear uses its excellent sense of smell to locate a seal breathing hole,and crouches（蹲）nearby in silence for a seal to appear.When the seal exhales,the bear smells its breath,reaches into the hole with a forepaw,and drags it out onto the ice.The polar bear kills the seal by biting its head to crush its skull.create in the snow.,The polar bear also hunts by stalking（跟踪）seals resting on the ice:Upon spotting a seal,it walks to within 100yd(91m),and then crouches.If the seal does not notice,the bear creeps（缓慢前进）to within 30 to 40 feet(9.1 to 12 m)of the seal and then suddenly rushes forth to attack.A third hunting method is to raid（突袭）the birth lairs（巢穴）that female seals,Reproduction and lifecycle,Courtship and mating take place on the sea ice in April and MayA male may follow the tracks of a breeding female for 100km(62mi)or moreafter finding her engage in intense fighting with other males over mating rights,fights which often result in scars and broken teethPolar bears have a enerallypolygynousmating system,Maternity denning（穴居）and early life,After mating,the fertilized egg remains in a suspended state until August or September.Between November and February,cubs are born blind,covered with a light down fur,and weighing less than 0.9kg(2.0lb),Life expectancy,Polar bears rarely live beyond 25 years.The oldest wild bears on record died at age 32,whereas the oldest captive was a female who died in 1991,age 43.,THANK YOU FOR LISTENING,BBC之杀戮战场BBC.Battlefields,