Marine invertebrates are some of the most bizarre and beautiful animals on the planet, thriving in the toughest parts of the oceans. Divers swim into a shoal of predatory Humboldt squid as they emerge from the ocean depths to hunt in packs. When cuttlefish gather to mate, their bodies flash in stroboscopic colours. Time-lapse photography reveals thousands of starfish gathering under the Arctic ice to devour a seal carcass, and a giant octopus commits suicide for her young.

Originally released by BBC Worldwide Learning, 2009. Streaming video file encoded with permission for digital streaming by Infobase on November 21, 2019.