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But what about our precious friends the coelacanths? Edit: foolish me coelacanths are not tetrapods But a better question may have been regarding the lungfish

• goodmatt 1y ago
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• quietbritishjim 1y ago
  First of all: I think it's ok if the definition of fish is a bit blurry around the edges. But actually I think coelacanths are quite a fun example. I hadn't heard of these before, thank you! Yes, they're not tetrapods, but (I've just discovered) they're not even vertebrates (no spine). According to my definition, they shouldn't be fish, but they do seem quite fish like. They are chordates (they have a spinal cord, just no backbone for it), so I could expand my definition to any chordate that isn't a tetrapod. But there are some rather non-fishy chordates [1] so that doesn't work either. [1] https://en.m.wikipedia.org/wiki/Tunicate https://en.m.wikipedia.org/wiki/Tunicate (For those that don't know, the top level subclassification of animals is phylum. There are a lot of phyla but a common ones are chordates (all vertebrates plus a few odd animals like discussed above), arthropods (insects and insect-like things like spiders and crabs), and molluscs (like slugs and clams). When I was at school, animals were just vertebrates or invertebrates but the reality is more interesting. I went down that rabbit hole when I found out that, weirdly, octopuses are molluscs.)
  • IAmBroom 1y ago
    > They are chordates (they have a spinal cord, just no backbone for it) None of the cartiligenous fish have backbones. Nor any other bones. Coelacanths have backbone-functioning cartilige.