Scientists find what made some whales the largest animals on Earth

U.S. and Canadian researchers have discovered a grapefruit-sized organ in the chin of rorqual (baleen) whales that controls the expansion of their massive jaws during feeding and that has allowed them to become the largest animals on Earth.

Rorqual whales include blue, humpback and fin whales, and the largest of them, blue whales, can grow to more than 100 feet in length and a weight of more than 150 tons.

That massive size occurs despite the fact that the creatures eat only small fish, krill and other small organism in the ocean. The whales do this by filter feeding. The rorqual whales have a lower jaw with folds like an accordion and jaw bones that allow it to expand significantly.
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