大象传媒

David Attenborough visits the Balearic wall lizards that live on an island off Minorca. Some of the lizards run up and down his arm, giving him the occasional nip as they try to work out what he is. The lizards are primarily insect-eaters but during the flowering season they also eat nectar, taking it from plants like the spurge which is very common. However, they have a very special relationship with the dead-horse arum flower which looks and smells like carrion, thereby attracting carrion flies. And it's the flies that the lizards are after. Thermal-imaging cameras show that the chemicals that produce the bad smell in the flower also give off heat so that the flower is five degrees warmer than the surrounding country. The cold-blooded lizards take advantage of this and sit on the large flower to warm up and wait for flies to be lured on to the flower by the smell. Hearing a fly buzzing inside, the lizard crawls into the flower, blocks the entrance, and grabs itself an easy meal. Two months later the arum flowers have shrivelled and produced their fruits. Until 20 years ago the lizards left the fruit pods alone but then one discovered that the arum seeds were good to eat. The habit spread and now the whole lizard population has become arum fruit-eaters. This also helps the plant, as the seeds germinate more easily after being digested. As a result, the arums are now abundant on the island where once they were scarce.