• teawrecks
    link
    fedilink
    arrow-up
    1
    ·
    17 days ago

    I’m not an expert, but my understanding is that the science indicates all mammals have a common ancestor. Not certain about fish, but I think that’s a similar case?

    To me, the surprising part about carcinisation is that, the form of a crab seems oddly specific, but non-obvious. I mean, I look at the form of a fish and think, “yeah, it makes sense why that shape would be favored in water,” but I look at a crab and think “guess that’s just what worked out for your ancestors. Tough luck, buddy.” But apparently it’s not just bad luck, it’s a common strategy.

    • Dasus@lemmy.world
      link
      fedilink
      arrow-up
      1
      ·
      17 days ago

      Not certain about fish, but I think that’s a similar case?

      Did you know humans are more closely related to catfish than catfish are to dogfish?

      QI | No such thing as a fish

      ¦“yeah, it makes sense why that shape would be favored in water,”

      Yeah, I can see that. But also it’s swimming in water. Then again if tou want to crawl around the bottom? Hexapod is probably the way to go. But then you also need to be able ro manipulate shit, so frontlimbs become bigger.

      Like a lot of space vehicles meant for surface exploring, both imagined and real, are usually six-wheeled, probably for added stability in a rocky terrain where there’s a bit less gravity and sometimes storms and whanot. And what is it like on the ocean floor? Rocky, basically “less gravity” and odd flows like storms.

      Idk there’s a bit more to it I guess, I’m just looking for what that bit is, or if there indeed is one.

      • teawrecks
        link
        fedilink
        arrow-up
        2
        ·
        edit-2
        17 days ago

        Yeah, that QI clip came to mind when you mentioned it, but to your point the shape that we consider “fish-like” shows up a lot in water. Even whales and dolphins figured out a similar shape, despite them not being fish (though they might still be etymologically related if you go back far enough?)

        Ok, I can buy that the shape of a crab is probably optimized for a certain lifestyle.