How Whale Evolution Kind Of Sucked

Mystacodon is the earliest known mysticete, the group that, today, we call the baleen whales. But if this was a baleen whale, where was its baleen? Where did baleen come from? And how did it live without it?

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[DanaBanana]

Whales are always mindblowing to me. Like, they were land animals at some point, that seems crazy. Imagine elephants evolving to feed from the ocean and they "lose" their legs over millions of years to transform them into fins. Evolution is wild.

[Xnaut]

An often-overlooked clue that can used to estimate the evolutionary age and origin of mysticetes lays not in the whales themselves, but their parasites. Whale lice have an unusual life cycle where the adults live on and within a baleen whale's skin in a manner that superficially resembles a barnacle, but when they reproduce their larvae only spend a short time in the water column before settling on the seafloor to continue their growth.

Once they finish their second stage they need to reattach to a whale to become an adult, and that can only happen by a whale touching its skin against the seafloor for the lice to grab onto. This makes whale lice very rare on species that spend their whole life filter feeding in the open water column, but much more common on species that feed on the seafloor like gray whales. It's also why odontocetes never contract whale lice, as none are specialized to hunt exclusively on the seafloor.

It's likely that whale lice have been coevolving with mysticetes since their divergence from odontocetes so by tracking their evolutionary history it could be possible to estimate when the first true mysticetes appeared, as well ad infer that feeding in seafloor sediment was the original driving force that started their distinct evolution.

[Joe_Potts]

At around the 7:30 minute mark, i was thinking "So why did this whale evolution suck?" then i realized it was the suction feeding and was like "Oh..." PBS Eons is smooth with the puns today.

[Gaarafan]

What's most mind blowing to me is how agile such large creatures can be. That footage of the whale flipping over 180 degrees is amazing.

[gabrielruiz]

The sheer amount we've been able to put together about prehistoric earth is amazing. I feel so lucky to be alive at this time

[davidg]

Coincidental timing: the US Navy just released some video of camera footage from their dolphins (cameras mounted on the dolphins), and the researchers found that suction feeding was their main way of catching fish. It isn't pure suction feeding, since the dolphins aren't still, but it's also not ram feeding (swimming faster than the fish) or biting the fish to disable/kill it before swallowing it.

[cheifOO]

I really like that you list the names of all the creatures involved in the story. Makes it easier for me to look them up.

[Reyma]

Mystacodon, a early mysticete has hind flippers and early odontocetes also have this trait. Thus, the two groups of modern whales lost their hind-limbs independently. I used to assume that modern whales lost their hind flippers as soon as they branched off from the archaeocetes.

[animalpeeps]

Ahhh yess! I wrote a research paper on the evolution of baleen in one of my paleontology classes in college! It is such a fascinating concept as to how it happened and how successful it has become. Thank you guys for making a concise, super educational and descriptive video on something that I don't see discussed too often!

[Cylume.]

I'd say whale evolution kind of Blows. 🐳

[aste]

What really blows my mind is how, at least in many toothed whales, their trachea _passes up through the middle of their esophagus?!_ I had assumed it would evolve to go _around_ the esophoagus, not pass through it like a deepthroat nasal septum. Now I wonder if that's the case for baleen whales too, especially since they retain two nostrils while toothed whales went to a singular one.

Come to think of it, I wonder how their trachea and one vs two nostril blowholes evolved...

[x]

I can't tell you how nice it is, to come home to see PBS Eons sitting in my inbox, ready for me to watch and learn some more about the life of this world. followed by melting my brain watching spacetime - cheers PBS Eons team 💌

[Bolihunter]

An episode about seal evolution would be cool!!! Another sea mammal thats so specialized for the ocean, fascinating

[egg]

Ooh I'm glad this is being covered, its not a common thing talked about in most whale evo vids

[johnwalters]

Interesting video! The Gray Whale is usually considered to be the most primitive of the extant mysticetes, and it does something similar to the suction feeding you describe, only with baleen rather than teeth. The Gray Whale spends the summer in the Bering Sea, where it feeds on bottom-living amphipods (small crustaceans similar to beach fleas), taking in mouthfuls of mud and straining them through its baleen plates.

[ordinaryorca]

This was great, could you do a similar video on the signature trait of their teethed cousins, odontocetes' echolocation? Exploring it from a bat perspective would also be cool, especially wiyh their arms race with certain moth species. No pressure though, not all vids need to be whale themed

[paulmurray]

Could you please address the evolution of the blowhole? Nostrils that moved further and further back?

[kitchenmom]

I love all your videos, not only do I learn new cool things I can impress my teenagers with at dinner, you also make it fun with your joy for sharing this knowledge with us. So thank you all for being amazing.

[gryphonrampant]

The revelations about suction-feeding whale ancestors on the ocean floor makes me curious about the omission of whiskers in the paleoart. When suction-feeding was mentioned, I immediately thought of walruses--who, interestingly, have large keratin filaments near their mouth in the form of sensory whiskers. I don't know how plausible a migration from bottom-feeding sensory whiskers to filtering baleen is, but I'd like to hear more.

[JJ-oqtz]

Modern day whales are believed to have moved into the oceans around the Teyths Sea, now in Mediterranean Sea and Asia. Fossils recoverd showed an animal called Archaeoceti, thought to be the first sub order of cetaceans, existed in the estuaries of Tethys Sea. I want to learn about hippos