SeetheDifference

Haveyoueverheldalizard,asnake,oraturtle?Itsbodytemperatureislikelylowerthanyours.Youcouldn’ttellthatjustbylooking.Youprobablywouldn’tbeabletofeeladifference,either.Butyoucanseethedifferenceinthermalinfraredimages.Theyshowhowcoolorwarmanobjectisbymeasuringtheamountofheatitgives off. 

hand

lizard

HOTTER

COLDER

Byfanningitsears,thiselephantbeginstocool down.

Thisspider’sbodyiscoolerthanits environment.

Lookatthethermalimagebelowofsomeoneholdingalizard.Thebrightredoftheperson’shandshowsawarm,steadybodytemperature.Thisistrueeventhoughthesurroundingairis cooler.


Thelizardshowsupmostlyasshadesofblue.Beforebeingheld,itappearedasdarkblue,likethebackground.Nosurprisethere!Thelizard’sbodytemperaturewasthesameasthetemperatureofthesurrounding air.


Butwhathappensasthereptileandmammaltouch?Thereptileabsorbsheatfromtheperson’shand.Itsbodyiswarming.Itsfeetandlegsshowupasgreenandyellow.Whatwillhappenifthepersoncontinuestohold it?

HOTTER

COLDER

Thiscatgeneratesitsownbodyheat.
Itleavesbehindatrailofwarm pawprints.

Watchasapersonleaves
warmfootprintsona cold floor.

COLDER

HOTTER

gharial

Thisgharialsoaksupthesun’srays.Thenitsbodytemperature rises. 

Chemicalreactionsfromfoodalsoprovideenergy.Andenergyproducesheat.Inthisway,ananimal’sbodyislikeafurnace.Butinsteadofburningnaturalgas,thebody“burns” food.


Thefasterananimal’smetabolism,themoreenergytheanimalhasforkeepingwarm.Whichanimalsdoyouthinkhavethefaster metabolism?

ALivingFurnace

Whycansomeanimalskeepthesameinternaltemperaturewhileotherscannot?Theansweris metabolism.


Ananimal’smetabolismisallofthechemicalreactionsthattakeplaceinitsbody.Tiny moleculesareconstantlycombiningandbreakingapartinbodycells.Theyformnewsubstances.Mostofthesechemicalreactionsoccurasfoodbreaks down.


Foodprovidesthematerialstogrow.Italsorepairsdamagedcells.Ifyoucutyourfinger,newcellsgrowoutfromeithersideofthecutandhealit.Thenewcellscomefromthefoodyou eat.

HOTTER

COLDER

meerkats

Thesemeerkatsdon’tneedtowaitforthesun.Theycontroltheirownbodyheatandarealready warm. 

flamingos

HOTTER

COLDER

Someoftheseflamingoshaveonelegthatishotterthantheother.  Whenaflamingostandsononeleg,thatleglosesheat,whiletheotherlegistuckedupnexttoitsbodykeeping warm. 

Youguessedit—endotherms.The metabolism ofbirdsandmammalsisfastenoughtoproduceconstantwarmth.Thisallowstheanimalstomaintainahighbodytemperature.Birdshavethefastestmetabolismandthehighestbodytemperature, 40oCto 42oC (104oFto 108oF).


Canyouthinkofareasonbirdsneedsuchafastmetabolism?Thinkabouthowbirdsmove.Thehighrateofmetabolismproducestheenergybirdsneedto fly.