Eden's whales, which inhabit the waters off the Japanese coast as well as other areas, wait upright for fish to come into their mouths on the surface of the sea in an apparent bid to conserve energy, an international research team including Japanese and Thai researchers has found.
The team, which has announced their research results, says such a passive method of feeding has not been confirmed among other species of whales.
The researchers made the finding after observing Eden's whales that feed on fish near the surface of the Gulf of Thailand.
According to the team, the gulf is short of oxygen and fish only live near the surface of the water.
Noting that Eden's whales are not seen to feed this way in other areas and that the whales and their calves wait upright on the surface together, researchers say individual whales that have figured out how to catch fish this way in the area have handed down the technique to their calves.