Can You Guess What's Happening in This Giant, Underwater 'Tornado' Made of Fish?

This swirling mass of fish is real and actually part of the mating ritual of the fish. (Photo: Octavio Aburto)

This swarming school of fish creating a giant underwater ball, vortex, tornado or whatever else the picture calls to mind was something scientist and photographer Octavio Aburto had been wanting to capture for nearly three years, according to Mission Blue.

The image, called "David and Goliath" in its submission to a National Geographic contest, is actually a mating scene. Here's more about it from its photo contest description:

Together with my friend David Castro, we were diving with a large group of Bigeye travellies at Cabo Pulmo National Park, Mexico. Thousands of fish forming a ball during the reproduction courtship. In the afternoon, these fish congregate to form a large spawning aggregation around the reefs of the National Park.

Aburto explained to Mission Blue in a Q&A that he's had many question whether such a photo is real.

"My response to these questions has been this — of course it is real. Fish, as is the case with many other animals, have certain behaviors that they perform when they reproduce," he said according to Mission Blue.

He also recently posted this video to show off footage from the conditions in which the photo was taken:

Aburto said in the Q&A that he and Castro followed the fish for an hour "waiting for them to start performing the courtship behavior."

"When the fish formed the tornado, David happened to be in this position filming this spectacular event," he continued.

(H/T: DVice via Geekologie)