Evolution Of Whales (Patreon)

On my last post I was asked to go over the evolution of aquatic mammals, which is always a fun topic! I was asked to cover whales, pinnipeds (seals and walruses), and sirenians (dugongs and manatees), but when I was drawing I forgot to include sirenians ooops. I'll touch on those at the end anyway, even if there aren't illustrations of them!

So a long time ago our ancestors crawled out of the ocean because it sucked to live there, as it was full of giant sea scorpions and big fish and all manner of horrible parasites. But all those foul creatures followed us, and now the land ain't much better, and some of us got buyer's remorse about the whole sea-to-land transition and decided to move back to the terrible ocean.

One of those animals was a small herbivorous hoofed animal related to hippos and pigs, and is the ancestor of modern whales. There are three main kinds of modern whales-- baleen whales (the whales with those weird brushy mouths), toothed whales (whales with teeth, including beaked whales), and dolphins, which are a kind of toothed whale. The largest animal that's ever lived is a whale-- the blue whale, which is larger than even the most gargantuan dinosaur. This thought comforts me when I think about how much I would have liked to see a dinosaur: at least our time has a big animal, too.

Not all aquatic mammals descended from one ancestor, however. Pinnipeds evolved from an ancestor in a separate group of mammals, carnivora. It's closest relatives were bears and mustelids (weasels and badgers). You might notice that in the evolution of whales, the tail takes on a big role, eventually becoming the main way whales propel themselves through the water. Pinnipeds, however, use their feet to swim, having almost completely lost their tails. Some folks theorize that this difference means they'll never become fully aquatic, as having four feet (even if some of those feet are flippers) means they can still get around fairly well on land. That's useful because it's safer to give birth on land (far away from orcas) so it's an advantage that might not go away. It ain't a sure thing, I'm sure evolution would surprise us, but whales evolved preeetty quickly and seals have had plenty of time to catch up if they were gonna...

And lastly the group I so woefully forgot to illustrate is the sirenians, which evolved from yet another separate group of mammals, the group containing elephants. They returned to the water around the same time as whales, and in much the same way, gradually reducing their back limbs and evolving a powerful tail for swimmin. However, they kept to their herbivorous roots, and remain the only fully aquatic herbivorous mammals. Early sirenians looked a lot like hippos and lived a similar lifestyle, though the two aren't related.

So there you have it! That's how whale happen. Thank you for reading my XL post-- I'm afraid it's the only one for the months of May and June, since it's pretty chunky, so I'll see y'all again in July. Let me know if there's any particular beasts (including plants and bugs, I got no limits) you'd like me to discuss, I'm always open to suggestion.

Thank you for your support, you lovely people!

-Abby