Blue whales represent the largest creature on this planet and perhaps also the biggest to have ever lived. Therefore, it is not surprising that it has a huge appetite too. But, until now the strategies employed by this behemoth to gather adequate food has not been fully understood.
On Friday, scientists said that a study of this interesting species off the Californian coast using tags to track the movements, their prey, the krill – a tiny crustacean resembling the shrimp shows that these marine mammals are far from indiscriminate grazers as has been thought for long. Instead, they take to intense feeding when the density of krill is high and stay off when the density falls so that oxygen is saved for future dives.
Elliott Hazen from U.S. National Oceanic and Atmospheric Administration said that the researchers found the blue whales having a complex strategy of switching between intense foraging even at the cost of oxygen when the quality of prey was high and conserving oxygen when the quality of prey was low.
Blue whales are also filter feeders and use baleen plates in their mouth. These plates are made of keratin which is also found in the fingernails of humans, to strain the krill from ocean waters.
During lunge-feeding, the whale moves at top speed opening its mouth. It then gulps in a mix of water and prey which is about 130% of its body mass. Its throat bloats with water and the throat muscles are used in conjunction with the tongue to force the water out of the mouth via the baleen plates which work as a sieve keeping the krill inside.
The blue whales eat up some 4 tons of krill every day.
Ari Friedlaender from Oregon State University stated that the whales actively assess their environment and use the density of their prey in ways that were not known earlier in order to maximize their energy gain.
The study comprised of information from over 50 whales that were tagged via suction cups and data on their prey. Blue whales found in oceans across the globe are classified as endangered species. This followed the large scale whaling during the 20th century that nearly brought the species to the verge of extinction. Presently their global population is about 10,000. These marine mammals can grow up to some 98 feet in length and 180 tons weight.