• chaos@beehaw.org
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      3 days ago

      There isn’t a simple evolutionary definition of “fish”, not the same way there is for, say, mammals. If you found the common ancestor of everything we call a mammal and said “everything descended from this one is also a mammal”, you’d be correct. If you did that for everything we call fish, every animal in the world would be a fish. Also, we decided which animals were fish mostly on vibes, so without a clear definition you can pedantically argue that everything is a fish including mammals.

      • DragonTypeWyvern@midwest.social
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        2 days ago

        That’s not quite true. A lot of worms, for example, wouldn’t be fish, but all fish would be worms. Most invertebrates also wouldn’t be fish.