Titans of the Deep 2017 saison 01 episode 01

More than 50 million years ago, the ancestors of the Whales and other Cetaceans adapted to living in the ocean. This might seem like a backward step: how could a mammal breathe, give birth, suckle its young, sleep and feed underwater? Nonetheless, they succeeded in conquering the depths of the whole planet. To survive, they developed mysterious means of communication and new hunting techniques.