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15 March, 2007
I also loved the marine iguanas, which Darwin, with typical Victorian prejudice, likened to ‘imps of Satan’. These are remarkable animals: they spend most of their time ashore, basking in the sun, but feed under water. They are not swimmers; they simply walk through the crashing surf and continue on their way until they’re under several feet of water, where they wander around munching on seaweed. When they’ve eaten sufficient, they walk out again, clinging with sharp claws to the rocks when the surf tries to drag them back under. They too, are considered tasty snacks by many introduced animals, but seem to be surviving surprisingly well. The Galápagos are not islands that have separated from landmasses, such as New Zealand, but are brand new growths, thrown up by volcanic eruption. This is one of the reasons why their evolving wildlife is of such interest. All the animals (with the exception of man’s introductions) have arrived ‘accidentally’. The assumption is that most of the land animals arrived on some from of raft, debris from a large flood; a fallen tree – that type of thing. What is still a puzzle is how so many tortoises arrived, especially as they have evolved into quite distinct sub-species, which does not suggest that they have travelled from one island to another. An interesting recent discovery has been made by a couple who have been studying some groups of finches on one island for about 20 years: these birds are specialising and evolving even as they watch them. Evolution can, in fact, be a fairly rapid process.