It takes a tremendous amount of energy to move the largest animal on Earth from a standstill to chasing food in a fierce dive. Could the krill that a blue whale catches in its gargantuan mouth really provide a high enough calorie count to make all this effort worthwhile? To find out, Jeremy Goldbogen tagged whales with data recorders and monitored hundreds of their dives. It can take 770 to 1900 calories to get the whale moving, but it's worth it. From Ed Yong:
When Goldbogen plugged the data from his recorders into a simulation of a feeding whale, he found that the lunge is staggeringly efficient. Despite the massive outlay in energy, the whale easily recoups anywhere from 6 to 240 times that amount, depending on how big it is and how tightly packed its krill targets are.
If a big whale attacks a particularly dense swarm, it can swallow up to 500 kilograms of krill, eating 457,000 calories in a single monster mouthful and getting back almost 200 times the amount it burned in the attempt. A smaller whale lunging at a sparse collection of krill would only get around 8,000 calories, but that’s still 8 times more than what it burned. Even when Goldbogen accounted for the energy needed to dive in search of prey, the whales still regained 3 to 90 times as much energy as they spent.
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Image: Wikimedia Commons