老托福听力93篇集锦:Part C(MP3+字幕) 第82篇:青蛙

可可听力网 2015年03月05日 17:29:00
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      Ifyoulikedthecolorfulanimalswejustsaw, you'regoingtolovethesenextanimals.Frogs.

      Youmightnotnormallythinkoffrogsasbeingcolorful, butthesefrogsdefinitelyare.

      Theyarethedart-poisonfrogsofCentralandSouthAmerica.

      Lookattheirstrikingcolorsoftenyellowwithblackstripesordeepbluewithblackspots.

      Beyondbeingnicetolookat, thesemarkingshaveapurpose.

      Theywarnpredatorsthatthesefrogsarepoisonous.

      Whenthreatened, thesefrogssecreteasubstancethroughtheirskinthatwouldeasilykillwhateveranimalmighttrytoeatthem.

      Theirbrightcolorscommunicatethis, andsomostanimalstendnottohuntthem.

      Now, speakingofhunting, forcenturiesthesefrogsweresoughtafterbyhunters.

      Asyoumightthink, thehuntersdidn'twanttoeatthefrogs, butrather, theycapturedthemfortheirpoison.

      Theywouldaddthepoisontothetipsoftheirhuntingarrowsofcourse, nowadaysmosthuntersuseguns.

      Thesedaysdart-poisonfrogsareoflessinteresttohuntersthantomedicalresearchers.

      Researchersbelievethattheycanmakenewheartmedicinefromthepoison, becauseitactsasastimulantonthebody'snervoussystem.

      Researchersthinktheycoulduseittostimulateaweakheart.

      Thereis, however, aproblemwithdoingresearchonthesefrogs.

      Thosethatarecaughtinthewindwillproducetheirpoisonuntiltheydie.

      However, thosethatarebornincaptivity, liketheonesyouseehere, willnotproduceanypoisonatall.