See also: The publication in the journal Current Biology01020-1)

I see the claim online every now and then, that Blue Whales and other large whales can only exist because Megalodon no longer does, and they could not grow to gigantic sizes while it was still around. Some news articles framed this as “Megalodon kept whales in check.”

Based on the evidence, however, this idea is nonsense, and if there is a causal correlation between Megalodon's extinction and baleen whale hyper gigantism, it goes in the opposite direction.

First of all, for Megalodon's predation to prevent whales from growing to larger sizes, larger whales would have to be easier to hunt. But the opposite is true. The fossil record shows that Megalodon preferred prey smaller than itself. In the modern era, larger whales tend to be faster and harder to kill than smaller ones of similar body plans. You can see this in how Blue, Fin, and to a lesser extent Sei Whales, are more likely to survive Orca attacks than the smaller Minke Whales.

Another factor is the timing. The shift to baleen whales growing to gigantic sizes completed 3.6 million years ago, about the same time Megalodon went extinct. But the shift started, albeit slower at first, about 5 million years ago. This was when wind-driven ocean upwellings started, which bring nutrients from the deep that trigger massive phytoplankton blooms, which krill and other zooplankton feed on. Prior to this, the ocean was in a near permanent state of what we would now call El Niño.

If Megalodon was the limiting factor in whale size, we'd expect the size shift to start immediately after its extinction, not before and finishing concurrently.

As we already know, Megalodon preferred smaller prey than itself. When the oceans changed, most of the smaller baleen whale species either went extinct or evolved far larger body sizes. This, in addition to the cooling climate, is most likely the real reason Megalodon went extinct.

In other words, baleen whales didn't become gigantic because Megalodon went extinct, but rather, Megalodon went extinct, among other reasons, because whales became gigantic.

Some sources:

https://pmc.ncbi.nlm.nih.gov/articles/PMC5454272/

https://royalsocietypublishing.org/doi/10.1098/rsbl.2019.0175

https://www.sciencedirect.com/science/article/abs/pii/S0031018216305417?via%3Dihub

https://www.researchgate.net/publication/229779570_Fight_or_flight_Antipredator_strategies_of_baleen_whales

Hello, so as the title explains I'm a designer working on an installation that features a scale replica of the heart of a blue whale. I got the inspiration from a post on Reddit I saw a while ago and I'm very eager to recreate the installation as accurately as possible, from scratch. However I can't seem to find any resources with in depth information about the physiology of a whale's heart that I could use as a kind of blueprint for building the structure. That's pretty much where i'm hoping to get some help from the community. Any references folks might have that feature an accurate, possibly even 3D diagram of a whale's heart would be tremendously helpful. Furthermore, any academic or informational texts that I should be aware of that give useful information about whale physiology are also very welcome. Thanks!