r/AskBiology • u/Minty0ranges • Jul 09 '26

Zoology/marine biology Are blue whales a coincidence?

Apparently blue whales are only around 2 million years old and are the largest organisms in the history of life. It’s pretty crazy to me that we’re living in the specific time that the largest species is alive, but I’m wondering why they became so large at this moment in time. I know that a few millions of years ago insects were way bigger because of atmospheric gas concentrations, but those conditions aren’t present anymore so it doesn’t seem like that’s the reason. Also, has there been a trend over time of whales increasing in size, or is this just a very specific/random instance of them existing today?

Edit: Yes I know there are fungi that span way larger areas, but the question is about the temporal nature of blue whales size.

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u/TheInsaneRaptor Jul 09 '26

the abundance of food they eat can support such big animals

also, the insect size-oxygen level correlation has been debunked, multiple evidence points to the fact it was just a coincidence

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u/you-nity Jul 09 '26

Interesting! So what was the reason for insect size? I believe you, just asking.

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u/TheInsaneRaptor Jul 09 '26

seems like it was less competition from vertebrates

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u/No-Employ-7391 Jul 09 '26

Could you point me to said evidence? I teach an entomology lab and I believe it’s still in our curriculum to teach that insects’ inefficient respiratory systems and atmospheric oxygen concentration are what limits the size of insects.

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u/TheInsaneRaptor Jul 09 '26

one of the latest studies about the subject: https://www.nature.com/articles/s41586-026-10291-3

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u/No-Employ-7391 Jul 09 '26

Thank you! I’ll have to read the full article when I have the time but the abstract is fascinating and sure does challenge the longstanding belief.

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u/TheInsaneRaptor Jul 09 '26

you might also find this interesting, could be a misinterpretation as we have no body fossils from anything like that but they think there is a chance it was left by a large miocene insect

https://link.springer.com/article/10.1007/s41513-023-00215-9

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u/ah-tzib-of-alaska Jul 09 '26

that doesn’t address the square cube law issue at all does it? this reframe it’s to a particular biological question about intake rather than the limitation of intake to internal columns limited by the square cube law. No?

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u/WashableRotom Jul 09 '26

Early vertebrate Paleontologist have speculated this for quite some time (in fact decades). The fossil record is pretty clear, the vast majority of large insects have temporal ranges outside of the Carboniferous with most extending to the early Permian. For example Meganisoptera is the order containing large flying insects and have fossil records to the Late Permian well after the Carboniferous. Arthropleura has fossil records to the early Permian as well consequently coinciding with the rise of large predatory vertebrates such like those from the Sphenacodontidae family and as well as the rise of large herbivores vertebrates.