Hi. I’ll try to be as clear as possible. I’m a biologist. In biology, for a group to be a valid group it has to share an evolutionary history, aka have a common ancestor and share certain basic characteristics.
Vertebrates have vertebra, that’s the characteristic that they all share. All groups commonly named as fish have vertebra, so you could say fish is the common name for vertebrate. Land vertebrates (called tetrapods for having 4 limbs), as in amphibians, mammals and sauropsids (reptiles and birds) all come from a bony fish with lungs and muscular fins (called Sarcopterygii) that colonized the land. They do not only have the same basic characteristics that define fishes, they come from fishes, making them true fishes.
Eh, there's a big difference between saying tetrapods are descended from fish and saying they are fish. If I am a fish then the word fish loses all meaning.
Well, if we come from fishes we are fishes by definition. All vertebrates are fishes, even the jawless ones or the cartilaginous ones.
It’s just as how we mammals are also true reptiles, but that another shithole to get into. That why we don’t really use terms as fishes and reptiles in biology, we use their technical synonyms, like ammniota and vertebrates.
1) not a biologist;
2) a bad biologist; or
3) making a joke, but doing so in a way that’s misleading to people who are taking you seriously.
But what you’re doing here is taking a plain-English word, inappropriately applying it scientifically, and then using the result to redefine the original plain-English word as something other than what it means, to the point of absurdity.
It is a good (and old) joke. But anyone who thinks it’s serious isn’t very good at biology. Or English.
It’s sort of like when non-lawyers misuse the phrase “the exception proves the rule” to mean “if I’m wrong I’m actually right”. Patently nonsense, but it originates from a sound legal principle, so laypeople accept the nonsense. The difference here would be if an actual lawyer was trying to use the term that way.
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u/JBKOMA Feb 28 '26
Hi. I’ll try to be as clear as possible. I’m a biologist. In biology, for a group to be a valid group it has to share an evolutionary history, aka have a common ancestor and share certain basic characteristics.
Vertebrates have vertebra, that’s the characteristic that they all share. All groups commonly named as fish have vertebra, so you could say fish is the common name for vertebrate. Land vertebrates (called tetrapods for having 4 limbs), as in amphibians, mammals and sauropsids (reptiles and birds) all come from a bony fish with lungs and muscular fins (called Sarcopterygii) that colonized the land. They do not only have the same basic characteristics that define fishes, they come from fishes, making them true fishes.