The Blue Planet - Season 1 Episode 5 Seasonal Seas

As the days grow longer, billions of microscopic plankton bloom under the blazing sun. Here in the temperate seas, three-ton basking sharks graze among forests of giant kelp - the fastest growing plant in the world. The forests harbor thousands of other animals, including sea otters, brilliantly colored anemones, squid, and exquisite leafy dragons. But as the year wears on, storms rage in the icy sea... a desperate challenge for the animals that remain.