How do penguins remain warm?
The next time you want to pull out your hair at a major traffic jam, just think of penguins. Researchers from the Alfred Wegener Institute in Germany have found that the jam’s signature stop-and-go motion actually plays a key survival role among Emperor penguins during the Antarctic winters.
The analogy can be explained in two parts: the jam and the micro-movements. The jam is the extremely tight huddle the penguins are in to share body heat during the harsh conditions. As for the go, an individual penguin only needs to move three-quarters of an inch to cause its neighbor to react and move close to it.
This sets off a change reaction of 1,000s of penguins moving like a wave. This movement keeps the penguins huddled as closely as possible to keep the penguins protected against the wind and cold.
To study the penguin huddle, the scientists at the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI), in Bremerhaven, Germany, used a mathematical model originally for studying traffic jams. The team compared the results from that model with an analysis of videos recording the real-life penguin huddles.
Unlike traffic jams, which generally (though not always if you live in Orange County, Calif.) only move forward, the penguin huddle can originate from any penguin and transmit in any direction. This usually starts a gap, called a “threshold distance,” grows between two penguins.
“We were really surprised that a traveling wave can be triggered by any penguin in a huddle, rather than penguins on the outside trying to push in,” said Daniel Zitterbart, co-author of the study, which is published in the Institute of Physics and German Physical Society’s New Journal of Physics.
“We also found it amazing how two waves, if triggered shortly after each other, merged instead of passing one another, making sure the huddle remains compact.”
The research team estimated that threshold distance to be around three-quarters of an inch. That distance is two times the thickness of the penguin’s compressive feather layer, which suggests that penguins just barely touch one another in a huddle. According to the researchers, this distance maximizes huddle density without sacrificing the penguins’ warmth from their own insulation.
The Emperor penguin is the only vertebrate species that can breed during the Antarctic winter, where temperatures can drop to -50 degrees Celsius. The male penguins, which are the ones that incubate the eggs, form huddles of thousands of individuals as they wait for the females to return from fishing.