Jellyfish drift through every ocean on Earth, some species found as deep as 8,300 meters, and marine biologist Gerhard Jarms of the University of Hamburg's Zoological Institute leads this survey of them, moving from cold water to tropical reefs. In the North Atlantic the crew films periphylla, a deep-dwelling species that spends its life far from sunlight, then travels to the Azores to find jellies sheltering in sea caves battered by rough surf. The film crosses to the Pacific for Jellyfish Lake, where millions of golden jellyfish that have lost their sting drift with the sun, and to the reefs off western Papua for a look at the corals that share their waters. It closes off Australia with the box jellyfish, among the most venomous animals in the ocean, filmed at close range. Along the way the film makes the case that jellyfish are not just curiosities: they anchor food chains that support the fish and marine mammals above them, feeding the migrations larger predators depend on.