The NOAA Fisheries, West Coast Region, has shed light on as to how blue whales maintain their huge size. As per them, whales, the largest creatures on earth, maintain their gigantic size through ultra-efficient foraging methods.

As per the researchers, the foraging methods must use the energy that whales gain by eating krill while conserving oxygen during dives. Study researchers have affirmed that foraging methods are more complex that what were being considered before.

The researchers have tagged blue whales and came to know that they target the densest, highest-quality prey, allowing them to maximize their energy gain.

Study's lead researcher Elliott Hazen, a research ecologist with NOAA Fisheries' Southwest Fisheries Science Center, said, "For blue whales, one of our main questions has been: How do they eat efficiently to support that massive body size. Now we know that optimizing their feeding behavior is another specialization that makes the most of the food available".

When whales feed, they take in huge amount of water and filter out small krill before releasing them. The researchers said that the process takes a lot of energy that requires replenishment.

In order to know how whales maintain their energy requirements, the researchers carried out comparative analysis of foraging between 14 tagged blue whales and 41 previously tagged blue whales off the coast of California. This data was then compared with acoustic surveys.

The researchers found that when krill were less dense in a given area, then whales fed less. But when krill densities were higher, whales fed more.

"Blue whales don't live in a world of excess and the decisions these animals make are critical to their survival," said Ari Friedlaender, a principal investigator with the Marine Mammal Institute at Oregon State University's Hatfield Marine Science Center and co-author on the study. "If you stick your hand into a full bag of pretzels, you're likely to grab more than if you put your hand into a bag that only had a few pretzels."

"If they are disturbed during the intense, deep-water feeding, it may not have consequences today, or this week, but it could over a period of months," Friedlaender said. "There can be impacts on their overall health, as well as on their fitness and viability for reproduction."