Blue whales are the largest living mammals on Earth, capable of growing as long as three full-length school buses. As you might come to expect, large animals have large appetites, and so blue whales don’t hesitate to feast whenever they find a large mass of the prey in one convenient location.
One of a blue whale’s favorite foods is krill, which often amass in large groups in the ocean. When a blue whale comes close to a large mass of krill, it will accelerate to around 6.7 miles per hour, open its mouth, and lunge directly toward the mass with the hope of filling its stomach. In this drone footage, we can see this happening.
As the whale opens its large mouth, its speed decreases substantially. This is because the whale’s mouth works against the aerodynamic properties of the whale’s body.
Worthy of note, blue whales only seem to bother with eating when the krill masses they discover are large. If the mass isn’t big enough, the blue whale may still swim through the mass of krill, but it doesn’t bother to open its mouth and lunge for the chance to catch any. Some scientists think this could be because the reward isn’t fruitful enough for the incredible amount of energy needed to lunge at the mass of krill.