SoakingUptheSun
Imaginetakinganaturehikealongacreek.It’sasunnyspringmorning.Thesunfeelswarm,buttheairis chilly.
Alargegrayrocksticksoutofamuddybank.Aflashofcolorcatchesyoureye.Youstepcloserandseealizardlyingontherock.Itsskinshimmersinthesun.Itisasstillas astatue.Isitsleeping?No!Thelittlelizardis sunbathing.
Lizards,snakes,andotherreptilesareectotherms.Fish,insects,worms,andfrogsareectotherms,too.Ectothermsproduceverylittleheatinsidetheirbody.Towarmup,theygetheatfromtheir environment.
Thedesertlizardbasksinthesuntowarmitself up.
Energyfrom thesunhelpsthisdesertlizarddartand dash.
That’swhythelizardissunbathing.Sunlightstrikesitsbody,warmingit.Therockabsorbsheat,too.Thiswarmsthelizard’s underside.
Atnight,thelizard’sbodybecomesascoolastheairaroundit.Thelowbodytemperaturemakesitsmusclesslowdown.Itwillneedthemorningsuntowarmup again.
HeatFromtheInside
Asyouhike,youhearasound:Clickety,clickety,clickety.It’sthesoundoftinyclawsontreebark.Twosquirrelschaseeachotheraroundatree trunk.
Unlikethelizard,thesefurryrodentsdon’tneedsunlightforenergy.That’sbecausesquirrelsandothermammalsareendotherms.Anendothermisananimalthatproducesenoughheattokeepitsinsides warm.
Squirrelsdon’thavetowaitforthesun.Theycanbeactivethemomenttheywakeup.So canbirds.Theyareendotherms,too.Andsocan you.
That’sright!Youareanendotherm.Itdoesn’tmatterifit’shotorcoldoutside.Theinsideofyourbodystaysatthesamewarm temperature.
What’sInaName?
Ectothermandendothermmaysoundlikestrangewords.Yet,theymakesensewhenyoubreakthem down.
EctothermcomesfromtheGreekwordsektos,meaning“outside,”andthermos,meaning“warm.”Anectothermgetswarmthfromoutsideits body.
EndothermcomesfromtheGreekwordendo,meaning“within.”An endothermgetswarmthfrominsideits body.
