The south pole is under invasion. Scientists have discovered that thousands, possibly millions, of king crabs are now clambering their way over the sea floor towards the antarctic.  "They are coming from the deep, somewhere between 6,000 to 9,000 feet down," said James McClintock, of the University of alabama, Birmingham. It sounds like a scene from a science fiction film - king crabs were thought not to tolerate low temperatures until, in 2008, scientists spotted one on the seabed near the antarctic. The scientists returned earlier this year and carried out a full survey: their results were dramatic.  "We discovered hundreds and hundreds of king crabs, which could translate into millions across broad expanses of coastal antarctica," said McClintock. "They appear healthy and have all the ingredients needed to produce a healthy population."  Just why this crab invasion is taking place is unclear, though most scientists believe human changes to the atmosphere, triggering global warming, are involved. as to the impact of this underwater invasion, this is now causing considerable alarm. The antarctic environment is pristine but fragile and could be badly damaged by invading king crabs.  "The whole ecosystem could change," said McClintock, who revealed that he has already been contacted by fishermen who want to start catching king crabs in the antarctic.