The blue whale is perhaps the largest animal that has ever lived, so it makes sense that it has an appetite to match. The strategies it uses to forage for food, however, have remained largely secret.
What's already known is that blue whales are filter feeders — using plates in their mouth to filter krill from the ocean. When feeding, blue whales dive into the depths of the ocean, accelerating and taking in as much water as 130 percent of their body weight. Blue whales can eat as much as four tons of krill per day.
A new study that took place off the coast of California sheds more light onto the eating habits of the blue whale. The study found that blue whales do indeed discriminate when it comes to krill — feeding only when krill counts are high, and choosing to conserve their oxygen for future dives when krill counts are low.
"We found that blue whales have a complex strategy of switching from conserving oxygen when prey quality is low, to intense foraging at the expense of oxygen when prey quality is high," said Elliott Hazen, a research ecologist from the U.S. National Oceanic and Atmospheric Administration's Fisheries Science Center.
Blue whales essentially assess their environment to take advantage of their prey in ways that were previously unknown. This maximizes energy gain from the krill that the whale does eat.
Blue whales are found in oceans around the world, but they are listed as endangered because of whaling practices in the past century. There are around 10,000 blue whales around the world, and they can be as long as 30 meters and weigh up to 165 tons.
Researchers hope that the new study will help them figure out how to better protect blue whales.