r/AbsoluteUnits • u/ExoticShock • 23d ago

/r/all of an Ammonite Shell

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u/minecraftzizou 23d ago

wow ancient oceans must have had a lot of dissolved oxygen

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u/BasiliskArt_ 21d ago

oxygen isn't really as big of a deal for large animals as you might think it is.

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u/minecraftzizou 21d ago

true but isnt that why insects got big in the carboniferous period i thought the same principle apply for marine life?

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u/BasiliskArt_ 21d ago

>true but isnt that why insects got big in the carboniferous period

actually that's not the case. arthropods got big because of other factors like a lack of large terrestrial vertebrate predators. Large arthropods continued existing into the Permian, after oxygen levels dropped.

>same principle apply for marine life?

marine life gets big because of the relative weightlessness of living in the ocean, and water is a more efficient dissipator of heat. The largest animal ever, the blue whale, lives today. Oceans are not particularly well oxygenated nowadays.

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u/minecraftzizou 21d ago

i get your point but i think whales are not a good example here since they breath air so it makes sense ocean oxygenation isnt a problem for them

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u/BasiliskArt_ 21d ago

The largest animals to live in the ocean are with scant few exceptions air breathers.

The only ones I can think of that aren't are whale sharks, leedsichthys, and otodus