Independent: An army of shell-crushing crabs is poised to invade parts of the Antarctic Ocean that were off limits to the crustaceans for millions of years because of the intensely cold water. Scientists believe that, as global warming causes sea temperatures in the region to rise, the unique shallow-water habitat of the Antarctic Peninsula will be transformed by the mass arrival of killer crabs. Crabs are one of the top predators of the seabed but their enforced absence from the cold …