Blue whales can dive for up to 15 minutes at a time to forage for food. While underwater, the whales lunge to consume as much krill as possible, by filling themselves up with water and then the whale's massive tongue forces the water out through the thin, overlapping baleen plates. For each dive, the whale has time to lunge at their prey between 1 and 6 times, consuming approximately 477,600 calories worth of krill in each dive. While a blue whale is feeding, the volume of krill-filled water in its mouth weighs more than it does: some 200 tons. Researchers calculated the speed of the whale, the drag effect of the water, and the volume and density of the krill-filled water consumed to conclude that the whales consume 90 times as many calories from each dive as they expend diving for food. That is what I call an effishent hunter.