How does a fossil hunter know they have found a different species of animal rather than just one oddly developed member of the same species?
Animals that live in the depths of the ocean have to tolerate near total darkness, enormous pressures and temperatures hovering around freezing. The darkness is because light can't penetrate deep water; the pressure because of the enormous mass of water pressing down from above. But what about the cold? This week one listener asks, if squeezing gases makes them hot, why are the ocean depths so chilly?
Is the high density of modern agricultural crops taking on the role played by rainforests and how do fossil hunters know when they have a new species or just an odd example of a well known organism.
And out of the archives comes an extraordinary recording, the sound of a living leaf struggling to suck in water.
Answering the questions in this week's programme are marine biologist Dr Helen Scales; Dr Nick Brown, a forest ecologist from Oxford University and Professor Philip Stott, an environmental scientist from the University of London.
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Presenter: Richard Daniel
Producer: Toby Murcott
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