“Theiguanasaresmall,andofasootyblack,which,ifpossible,heightenstheirnativeugliness.Indeed,sodisgustingistheirappearance,thatnooneonboardcouldbeprevailedupontotakethemas food.”
—CaptainJames Colnett
oftheBritishRoyalNavy, 1798
Whiletheiguanaswims,itsback spinesbalanceits body.
Partiallywebbed feethelpit swim.
Marineiguanasleftalastingimpressiononsomeoftheislands’earliestvisitors.WhenexplorerandnaturalistCharlesDarwinfirstseteyesonthemadecadeormoreafterCaptainColnett,he,too,foundthemunappealing.Hedescribedthemas“impsofdarkness.”Marineiguanasmaylookawkwardonland,buttheyrulethewater.Theydivetogreatdepthstograzeonbedsofalgae,likecowsgrazingona pasture.
Thesearetheonlylizardsintheworldwiththeabilitytoliveandforageatsea.TheyareendemictotheGalápagosIslands.Therearesixslightlydifferentspecies,eachfromadifferentisland.Scientistsbelievethattheydescendedfromlandiguanasthatfloatedouttotheislandsfromthecontinentonlogsorclumpsofvegetation.Tosurvive,theyhadtoadapt.Overtime,theirbodies changed.
SaltySneezes
Becausetheyswallowseawaterwiththeirfood,marineiguanasneedtogetridofsaltfromtheirsystems.Thesaltgetsfilteredfromtheirbloodandthenexcretedbyspecialglandsintheirnoses.Thesaltleavestheirbodieswhentheyprojectile sneeze!
Heat‑SeekingLizard
Marineiguanascannotregulatetheirbodytemperatures.Theymustrelyonanexternalsource,likethesun,todoitforthem.Ifyoureadlastmonth’seditionofExplorermagazine,you’llknowwhatthewordforthisis:ectotherm—acold‑bloodedanimal.Marineiguanaswillloseanaverageof10degreesofheatinthecoldwater.So,beforetheydivein,theytrytosoakupenoughheattoraisetheirbody temperatures.
