PlatypusesarefoundonlyinAustralia.Theyarea partofagroupofegg-layingmammalscalledmonotremes.

Millionsofyearsago,therewereafewspeciesofreptile-likemammals.Theyhadcharacteristicsoftoday’sreptiles,birds,and mammals.

Theyhadfurandnursedtheirbabieslikemammals.Theirfaceshadbirdbeaks.Theirskeletonswereshapedlikelizardskeletons.Andlikelizardsandbirds,theylaideggs.Thesespeciesdividedintothreegroups.Mammals.Birds.Reptiles.Overtime,mostegg-layingmammalsdiedoff.Today,onlytworemain:theplatypusandthe echidna.

What’sthefirstthingyounoticeabouttheplatypus?Ithasthefaceofaduck.Yet,itsbillisunlikeanybirdbeakoutthere.Itisflexibleandspongyandhasasmooth,suede-likeskin.Thebillisasupersensoryorgan,too,withnervecellstosensepressure,movement,andelectricity.Ithelpstheplatypusfeelitswayaroundtheunderwater world.

Thebillhassensoryreceptorsknownaspushrods.Theyareactivatedbypressureortouch.Theyaresosensitivethattheycandetecttinymovementsinthewater,aswheninsectlarvaemovejustafewinches away.

Theplatypusbillhastwomoretypesofnervereceptors.Theycandetecttinyelectricalsignalsmadebythemusclesinthebodiesoftheirprey.So,evenifalarvaorshrimparehiding,theydon’tstanda chance.

Beingwaterproofandwarmisvitalfortheplatypustosurvive.Evenincoldwinter,theplatypusgoesdivingforfood.Ithasahairyadaptationforswimmingincoldwater.Itiscoveredinthick,two-layeredfur.Thiskeepsbodyheatinandwater out.

Finehairsmakeupawoollyundercoat.Ontopofthisisasecondlayeroflongerhairs.Airistrappedbetweenthelayers.Thiskeepstheanimalwarmand dry.