Fin whales can swallow 'ocean soup' enough to fill a school bus

Scientists have discovered that while lunging towards krill and fish with an open mouth, a single fin whale can engulf up to 2,900 cubit feet of the ocean "soup", which is almost equal to a large school bus.

The whale, which can measure up to 88 feet in length, is left with about 25 pounds of krill after filtering out the water through special plates at the top of its mouth.

This is the first time that verifiable scientific testing procedures, instead of educated guesswork, have been used to calculate how much water and food whales can fit into their mouths.

The findings attain significance, as it is not easy to gather data on the massive mammals.

"Remember that you can't get whales to run on a treadmill in a laboratory," Discovery News quoted Nicholas Pyenson, a palaeontologist and University of California at Berkeley Department of Integrative Biology researcher, as saying.

"It'd also be impossible to hold a whale in place for research, not to mention the fact that their activity occurs under water and their size makes it next to impossible for a cameraman to hold a camera in the right position for any usable length of time," he added.

Published in Marine Ecology Progress Series journal, the study involved footage from Discovery's recent "Blue Planet" series, which showed a Bryde's whale lunge-feeding on a school of fish.

"The footage is extraordinary and is arguably the best for any rorqual (fast-moving lunge feeders). It serves as a vital source of information regarding the change in (mouth) gape angle over time," Pyenson said.

He and his two colleagues Jeremy Goldbogen and Robert Shadwick captured the footage into a computer program, and combined the data with information gathered in recent years from tiny recording devices stuck momentarily with plungers to the backs of whales.

Precise measurements of whale skeletons was also taken from museum specimens.

The analysis of the information thus combined suggests that fin whales fed in a series of lunges, each lasting six to 10 seconds. It also shows that a single dive incorporates up to seven lunges.

The researchers say that given the nutrition in 25 pounds of krill, a whale could meet its daily energy requirements in about four hours of hunting.

The study has also shown that the force of each whale lunge creates an enormous amount of drag that "essentially stops the whale dead in the water," forcing it to accelerate from a resting position, which requires a lot of energy.

Steven Vogel, a professor emeritus of biology at Duke University, said that the whale mouth "acts like a gigantic parachute on steroids when it's open," causing it to lose momentum from its lunge.

"The mouthful of water and krill is so large that it also changes the body shape of the whale, turning an otherwise streamlined swimmer into a slower mass," he added.