I'd be cautious of answers to questions like that that sound like a story. But i...

sethev on July 2, 2017 | parent | context | favorite | on: How do whales and dolphins sleep without drowning?

I'd be cautious of answers to questions like that that sound like a story. But it's worth pointing out that the ancestors of whales started out on land and it's not necessary to imagine they jumped straight from that to fully aquatic.