Here's survival of the fittest in action.

Watch this video of a giant grouper eating a black tip shark -- in one bite (skip ahead to the 30-second mark to get to the attack). It's kind of like you scarfing down Cheetos on your couch while oohing and ahhing as you watch Shark Week, except much, much more impressive.

It's no small feat, either, considering the shark measures four feet in length. Of course, the grouper is no slouch. It can live up to 50 years and swell to as many as 800 pounds, which means a shark is perfect to satisfy that voracious appetite.