北极熊英文介绍.ppt

ThelargestterrestrialcarnivorousanimalPolarbear

somepicturesaboutPolarbear

ThepolarbearisabearnativelargelywithintheArcticCircleencompassing（围绕，包围;）theArcticOcean,itssurroundingseasandsurroundinglandmasses.Itistheworld‘slargestlandcarnivore（食肉动物）andalsothelargestbear

PolarbearsInitsexistentspace,itisthetopmostfoodchain.Ithasthickfatandhairtostaywarm,itswhiteappearanceonwhitesnowisgoodprotectivecoloration,anditcanonlandandsea,soitcancatchfoodinthearcticinthisextremelyharsh（严酷的）climate.

EcologicalroleThepolarbearisthe?apexpredator（顶端食肉动物）?withinitsrange.Severalanimalspecies,particularly?ArcticFoxes?and?GlaucousGulls,routinelyscavenge（清除）polarbearkills.Therelationshipbetweenringedseals（环斑海豹）andpolarbearsissoclosethattheabundanceofringedsealsinsomeareasappearstoregulate（调节）thedensity（密度）ofpolarbears,whilepolarbearpredationinturnregulatesdensityandreproductivesuccessofringedseals.The?evolutionarypressure?ofpolarbearpredationonsealsprobablyaccountsforsomesignificantdifferencesbetweenArcticandAntarcticseals.

BecausepolarbearsplayanimportantroleinArcticenvironment,scientistsfeelthatpolarbearcanbeagoodindicatorofthehealthofArcticenvironment.So,wecansaythatbyprotectingpolarbears,weareprotectingthewholeArcticecosystem.12

Globalwarminghasanimpactontheice.Theiceismeltingquicklyinnorthandsouthpole.Andthathaveabadinfluenceonpolarbears.Duetotheglobalwarming,Arcticicebegantomelt,thepolarbear’shomehasbeendestroyed,thepreyisalsoacorrespondingreductionin

Polarbearsareindanger,wemusttakemeasurestoprotectthekindofbeautifulandlovelyanimal.Becauseitisthetreasureofnature.

Physicalcharacter”Thepolarbearsclawsareshortandstocky.theteetharelargerandsharperPolarbearfurconsistsofdenseunderfurand