Despite looking ungainly on land, once in the water the emperor penguin becomes an efficient predator. The streamlined shape of a penguin's body means that, although this species only reaches speeds of around 6-8km per hour, it can change direction and twist around quickly when chasing its prey.
The emperor penguin can claim to be one of the world's deepest-diving birds. In 1969 a team of American scientists established that the emperor dives to depths of 265 m (869 ft). This penguin can also stay underwater for 18 minutes which is far longer than any other bird.