Creatures of the Deep

S1, E8: An investigation of marine invertebrates and the way they thrive in the toughest parts of the ocean. Divers swim into a shoal of predatory Humboldt squid as the creatures emerge from the depths to hunt in packs, time-lapse photography reveals thousands of starfish gathering under the Arctic ice to devour a seal carcass, and a giant octopus protects her eggs by using her body to wall up a cave, starving to death in the process.