Forget sharknados, fish rain, fish monster rain, baby spider rain, and all other types of weather that happen to contain animals – reindeer cyclones are the only thing we're interested in today.

Footage showing the phenomenon has been spread around the Internet in the last few days, and you can easily see why.

The footage comes from a PBS documentary on Vikings, specifically a segment on attempts to hunt reindeer.

When startled, reindeer sometimes band together and keep moving in a constant swirling motion, in a behavior that is thought to confuse predators and make it more difficult to pick out a single animal from the herd.

"It's a defense strategy, designed to confuse any predator," PBS said in the documentary. "Whether wolf, bear, or Viking – achieving a clean kill in a swirling melee like this is difficult."

Similar defensive formations have been observed in fish, as well as forming into a large ball or tornado-like schools, scaring off even large predators.