Scientists May Have Finally Figured Out Why Whales Are So Big

[Narrator] Just a reminder, baleen whales are big.

Like the biggest creatures to ever grace planet earth.

The blue whale, for instance, tops out at 100 feet long,

over twice as long as the biggest of school buses.

But the funny thing is scientists have never

known for sure why they got so big.

Maybe it was because they could avoid predators better.

Or maybe it was just because they could.

On account of them being buoyant in water,

and not trudging along on land.

All wrong, according to a new study.

It was probably climate change.

And whales grew so big just three million years ago.

A sliver of time on an evolutionary scale.

The theory goes that when the ice ages came along

glaciers would periodically melt,

and wash nutrients into the sea.

Also during this time, upwelling from the depths increased

bringing even more nutrients.

These were eaten by tiny critters like krill,

which were in turn eaten by filter-feeding baleen whales.

By growing bigger, the whales had

a couple of advantages here.

For one, a bigger mouth can more efficiently gulp krill.

Two, larger baleen whales could store more energy.

So, they could afford to migrate to these food blooms.

Not only did this scenario allow bigger whales to thrive,

but nearly every species of smaller

baleen whale went extinct.

The result is that we're living

in an unprecedented era of giants,

unmatched by even the dinosaurs.

But the irony is, that while climate change made the giants

it could well imperil them.

Even tiny changes in ocean temperature

can monkey with the food chain, of plankton in particular.

How exactly this will shake out over the coming decades

no one knows.

But here's to hoping the giants can continue their reign.

(ethereal music)