With brand new baby chicks sheltering in so many of their brood pouches, warmth is imperative for Emperor Penguins in the coldest place on the planet. But how do you stay warm enough to survive in -40 degrees or colder?

In Adélie Land, Antarctica, this group of penguins demonstrates the dynamics of staying warm: ever-shifting positions within a massive huddle. This constant traveling wave of spiraling movement ensures that no penguin is on the outside of the mass for too long. From LiveScience in 2013:

…biologists and physicists based at the University of Erlangen-Nuremberg in Germany have collaborated to create mathematical models based on time-lapse camera footage of emperor penguins to try to understand the physics behind the huddles…

The team’s mathematical models showed that the huddles behave as waves instigated by any individual in the pack, no matter that individual’s location. If two waves travel toward each other, they merge, rather than passing one another. Gaps just 2 centimeters wide (0.8 inches) appear to instigate a reorganization, in order for the penguins to stay warm…

Watch them in this time lapse clip from PBS’ The Gathering Swarms.

Watch these next: Emperor Penguins Speed Launch Out of the Water and penguin babies taking their first steps. Plus: More videos in Antarctica and more incredible swarms.

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