介绍蝙蝠的英文短文

Echolocation

Inemittinghigh-pitchedsoundsandlisteningtoresultantechoes,theprocessusedinradartechnology,batsareabletolocatepreyandnearbyobjects.Thisistheprocessknownasecholocation,theabilitytheysimilarlysharewithdolphinsandwhales.

Twogroupsofmothsexploitabatsensetoecholocate:tigermothsproduceultrasonicsignalstowarnthebatsofthatmothsarechemically-protectiveoraposematic.Thiswasoncethoughttobethebiologicalequivalentofradarjamming,butthistheoryhasyettobeconfirmed.ThemothsNoctuidaehaveahearingorgancalledatympanumwhichrespondstoanincomingbatsignalbycausingthemoth'sflightmusclestotwitcherratically,sendingthemothintorandomevasivemanoeuvres.

Eyes

Althoughtheeyesofmostmicrobatspeciesaresmallandpoorlydeveloped,leadingtopoorvisualacuity,noneofthemareblind.Visionisusedtonavigatemicrobatsespeciallyforlongdistanceswhenbeyondtherangeofecholocation.Ithasevenbeendiscoveredthatsomespeciesareabletodetectultravioletlight.Theyalsohaveahighqualitysenseofsmellandhearing.Batshuntatnighttoavoidcompetitionwithbirds,andtravellargedistancesatmost800km,intheirsearchforfood.[2]

Wings

Thefingerbonesofbatsaremuchmoreflexiblethanthoseofothermammals.Onereasonisthatthecartilageintheirfingerslackscalciumandothermineralsnearerthetips,increasingtheirabilitytobendwithoutsplintering.Thecross-sectionofthefingerboneisalsoflattenedcomparedtocircularcrosssectionofhumanfingerbonehave,andisveryflexible.Theskinontheirwingmembraneshasmoreelasticityandsocanstretchmuchmorethanothermammals.

Thewingsofbatsaremuchthinnerthanthoseofbirds,sobatscanmanoeuvremorequicklyandmoreaccuratelythanbirds.Itisalsodelicate,rippingeasily.[12]Howeverthetissueofthebat'smembraneisabletoregrow,suchthatsmalltearscanhealquickly.[12][13]Thesurfaceoftheirwingsisequippedwithtouch-sensitivereceptorsonsmallbumpscalledMerkelcells,foundinmostmammalsincludinghumans,similarlyfoundonourfingertips.Thesesensitiveareasaredifferentinbatsaseachbumphasatinyhairinthecenter,[14]makingitevenmoresensitiveandallowingthebattodetectandcollectinformationabouttheairflowingoveritswings,therebyprovidingfeedbacktothebattochangeitsshapeofitswingtoflymoreefficiently.[14]Somebatslikethelittlebrownbatcanusethisdexteriousabilitywhereitisabletodrinkinmidair.[15]Otherbatssuchastheflyingfoxorfruitbatgentlyskimthewater'ssurface,thenlandsnearbytolickwaterfromtheirchestfur.[16]Anadditionalkindofreceptorcellisfoundinthewingmembraneofspeciesthatusetheirwingstocatchprey.Thisreceptorcellissensitivetothestretchingofthemembrane.[14]Thecellsareconcentratedinareasofthemembranewhereinsectshitthewingswhenthebatscapturethem.

Behaviour

Mostmicrobatsarenocturnalandareactiveattwilight.Alargeportionofbatsmigratehundredofkilometerstowinterhibernationdens[24],somepassintotorporincoldweather,rousingandfeedwhenwarmweatherallowsforinsectstobeactive[25].Othersretreattocavesforwinterandhibernateforsixmonths.[25]Batsrarelyflyinrainastheraininterfereswiththeirecholocation,andtheyareunabletolocatetheirfood.

Thesocialstructureofbatsvaries,withsomebatsleadingasolitarylifeandotherslivingincavescolonizedbymorethanamillionbats[26].Thefission-fusionsocialstructureisseenamongseveralspeciesofbats.Thetermfusionreferstoalargenumbersofbatsthatcongregatetogetherinoneroostingareaandfissionreferstobreakingupandthemixingofsubgroups,whereindividualbatsswitchingroostswithothersandoftenendingupindifferenttreesandwithdifferentroostmates.

Studiesalsoshowthatbatsmakeallkindsofsoundstocommunicatewithothers.Scientistsinthefieldhavelistenedtobatsandhavebeenabletoidentifysomesoundswithsomebehaviourbatswillmakerightafterthesoundsaremade[26].

70%ofbatspeciesareinsectivorous,locatingtheirpreybymeansofecholocation.Oftheremainder,mostfeedonfruits[27].Onlythreespeciessustainthemselveswithblood.Somespeciesevenpreyonvertebrates:thesearetheleaf-nosedbats(Phyllostomidae)ofCentralAmericaandSouthAmerica,andthetwobulldogbat(Noctilionidae)species,whichfeedonfish.Atleasttwospeciesofbatareknowntofeedonbats:theSpectralBat,alsoknownastheAmericanFalseVampirebat,andtheGhostBatofAustralia[27].Onespecies,theGreaterNoctulebat,catchesandeatssmallbirdsintheair.