From the giant bottlenosed whale and the West Indian manatee to the crabeater seal and hourglass dolphin, from the pygmy sperm whale to the spotted-necked otter, marine mammals are among the most fascinating - and most watched - of the Earth's many animal species. Some, such as dolphins, are known for their intelligence, friendliness toward humans and sophisticated social behaviour. In addition, all these animals are sources of fascination for the...