Whales are the largest animals on the planet, but they haven’t always been giants. Fossil records show that ancient whales were much smaller than the currently living behemoths.
So when did whales get so big, and how?
A new study suggests it might be due to changes in climate that affected the food that some whales eat: krill and small fish. Instead of being spread throughout the ocean, lots of krill started being packed into a small area. Bigger whales were simply more efficient at eating the dense pockets of krill, and they beat out their smaller cousins.
These whales use filters to feed on the tiny krill. Known as baleens, they include the largest whale on Earth — the blue whale. The baleen filter looks like bristles of a comb and is made up of keratin — the same stuff in our fingernails. To eat, the whale opens its mouth and takes in a huge gulp of water. Then it spits the water back out, and food like krill are caught in the baleen filter. It’s a highly efficient way to eat, allowing whales to pack on the pounds.
Photo: Gabriel Barathieu/Wikimedia Commons (CC BY-SA 2.0)
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