Frozen Seas (S01E04)

A look at the survival techniques of creatures that endure the harsh conditions of the Arctic and Antarctic. For animals at both poles, life is dominated by the annual retreat and advance of the freezing sea ice and the challenge of surviving winters when temperatures drop. In the Arctic the polar bear is the top predator, catching seals on the ice and forcing seabirds to nest high up on cliffs. In Antarctica the flightless penguins have no ground-based predators to deal with but lurking in the water is the constant threat from leopard seals. (BBC)