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听力材料：
Now, have you ever wondered why koalas hug trees?And apparently, according to a new scientific study itis to stay cool.That discovery was made byresearchers from the University of Melbourne whowere looking at how koalas regulate their bodytemperature.
And one of my students Natalie Briscoe, her PHD was focused on this question in terms of thekoala. And one of the questions we want to ask about the koala is, do they use behavior at allto regulate their temperature, are they able to choose places in their trees that make them abit more comfortable. And how did you go about finding this out?
Well, initially we went about this by putting a little weather station on a very long pole andlifting that weather station right up next to the koalas that we had radio transmitters on, and atthe same time going around to other random places in their habitat and measuring theconditions in the trees of those locations. But what Natalie noticed was that the koalas in thehot weather would come down and will go to the thicker trunks. And they would flop ontothose trunks and drop them limbs there. And we couldn't quite understand why they weredoing that, but she also sought to measure the tree trunk temperatures and we found thatthey are actually quite a bit cool than the air. And then we took a special kind of camera thattakes pictures of heat and tells us the temperature of every service in the picture. And it wasso obvious once we got those pictures back. What the koalas were doing? They were puttingtheir bottoms into the trees and dumping all their excess heating to the tree. And were you surprised by what you found because it's known or presumably zoologists knowthat the fur on the stomach of the koalas is a lot thinner than it is elsewhere.
Yeah, well, we knew that and we thought, well, maybe they, I guess one idea was that they justexpose that during the hot weather so that heat comes out their chests into the air. What wedidn't realize was how much cooler the tree trunks were than the air temperature. That wasn'tobvious to us. It was obvious when we looked at the trees with the special camera, but itwasn't before that. And then it made a whole lot of sense. And it's really surprised a lot ofbiologists. And it's always eucalyptus trees, is it?
No, it's not. And not all eucalyptus trees is good as each other for this purpose, so wemeasure a whole, a few different species of eucalypts in their habitat where we did the studyand also another kind of tree called acacia. And it turned out that the acacia was actually thebest one. But they don't eat the leaves of the acacia trees, they only eat the leaves of theeucalypt trees. 【不要走开，精彩内容请看下一页】
发表于 2016-8-18 20:38:58
