Blue whales, measuring up to 30 metres (100 feet) long and weighing 170 metric tonnes (190 US tons), are the largest animals in the world, and have been captured on film making strategic decisions on how to get their next meal of krill.

The video below taken off New Zealand by scientists from Oregon State University shows just how the whales pick and choose their meals.

"Modelling studies of blue whales lunge-feeding theorise that they will not put energy into feeding on low-reward prey patches," says Leigh Torres, principal investigator with the Marine Mammal Institute at Oregon State, who led the expedition studying the blue whales.

"Our footage shows this theory in action. We can see the whale making choices, which is really extraordinary because aerial observations of blue whales feeding on krill are rare."

The whale bypasses certain thin krill patches and targets others more lucrative.

"It certainly appears that the whale determined that amount of krill to be gained, and the effort it would take to consume the meal, wasn't worth the effort of slowing down," says Torres.

The rare footage was taken using small drones.

"It's hard to get good footage from a ship," Torres says. "And planes or helicopters can be invasive because of their noise. The drone allows us to get new angles on the whales without bothering them."

This article was originally published by Business Insider.