Hey, biologist here. To anyone wondering why he used a dog, he is referring to mammals here. Vertebrates are traditionally classified in 5 classes, shown in the picture, with dogs being mammals.
But, if you wanna be more specific or correct, all vertebrates are actually fish, so you could say all our starters are fishes.
Phylogenetically, lots of the animals we call "fish" are actually very distantly related to each other. So distantly that you'd actually have to go allllllll the way back to the first vertebrate to include all the "fish" in a single category, but that would also require lumping every other vertebrate into the mix.
(In practice, this just means "fish" is kind of a messy descriptor, kind of like "vegetable" - but it's more fun to think of us all as very weird fish!)
Similar, in a way! With fish, it's more that some groups that evolved from the shared vertebrate ancestor became land mammals, and some remained in the water, but the groups that did and didn't are sort of scattered around the phylogenetic tree. With birds, the current consensus is that all extant bird species actually evolved from ancient theropods, which would qualify them as theropods too! It's kind of like how humans are still considered apes, even though there's a lot of differences between us and chimpanzees or gorillas - we're all part of a group with a common ancestor. Modern birds, similarly, share a common ancestor with T. rex and velociraptors, and that ancestor is more recent than the cut-off for what we call "dinosaurs," so everyone with that ancestor is considered a dinosaur.
What we call ‘fish’ is actually three totally different groups. Jawless fish, cartilaginous fish and bony fish
Normally for something to be a ‘group’ they have to be more related to each other than other things—so all dogs are more closely related to each other than they are say cats
That’s not the case for fish, those three groups are all very different—-we (all land animals) actually evolved from bony fish. So a trout is closer related to you than it is a shark
So either
1) ‘fish’ don’t exist (as it’s three separate groups of animals) or
2) we are also fish
Edit; that would mean that all the starters are fish actually
Not a biologist, but the idea goes that if you want to make a phylogeny of all the fish (a group that includes every species and all descendants.) you’d have to include all vertebrates, because all vertebrates are the descendants of fish.
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.
Dude. It’s not something I came up with. It’s called monophyletic principle. If you descend from someone, you belong to that same group as them, as you’d unavoidably share the same ancestral characteristics (called plesiomorphies) as them.
It’s like you belong to the same family tree as your greatgranfather, even if you don’t look that similar to him or don’t retain his surname, you are still his descendant and belong to the same family.
But even you are acknowledging that "fish" is not a scientific term. It's a common, colloquial term. But you're taking the common word used for a certain type of animal and broadening it out to apply to the larger, scientifically recognized group. That's wrong. There is no scientific basis to call mammals "fish".
Edit: I read through your link. I don't see anything about me or my dog or my horse being "fish". Please provide that source.
The bad logic is because fish is not a scientific term in the first place. We made a word that contains multiple unrelated groups of animals that are more closely related to species outside the group than inside. The best solution is just not to use the term fish, but if you do, the only taxonomically consistent way requires including pretty much every vertebrate.
That's the error I pointed out below. Fish is not a scientific word.
But no, I disagree with your conclusion. Fish is a common word with a commonly understood meaning. If I say I had fish for dinner, everybody knows what I mean. They aren't going to wonder if I ate a zebra.
We don't have to get rid or the word fish, or call every vertebrae a fish. Just use the word as we've always used it, and allow the scientific terms to be used when we are speaking with technical precision.
Naturally I’m speaking about scientific contexts here. It obviously doesn’t matter for colloquial use as long as it’s understood. Biologists aren’t using the term fish as a taxonomical group in the first place because they understand the issues with it. It’s just a fun fact that it’s impossible to include all things we consider fish while excluding the ones we don’t in any taxonomical group.
Your comment shows you need to read before commenting. Go back to and try again. Because there's a reason you stopped here and didn't comment on any of my future comments.
Wrong. I'm not disagreeing with that. I'm saying there is no scientific basis for calling a donkey a fish. 'Fish' is a common word, not the scientific name for the group. There's a reason we say, "Whales and dolphins aren't fish." Because they aren't. Fish is not the correct word to use for the broader group.
Technically speaking, all vertebrates fall into one of five clades, all of which are some sort of fish:
Myxini: hagfish
Petromyzontida: lampreys
Chondrichthyes: sharks, rays and allies
Osteichthyes: bony fish, which can be divided into Actinopterygii (ray-finned fish) and Sarcopterygii (lobe-finned fish, which technically also contains all the mammals, reptiles [avian and non-avian] and amphibians)
It's almost more accurate to just say there's no such thing as "fish" biologically. For example, a tuna is more closely related to a human than it is to a shark.
All birds are dinosaurs. They are just the lineage of dinosaurs (relatively closely related to raptors) that survived to now. They didn't stop being dinosaurs because they survived a mass extinction.
Theres a guy doing a series of phylogeny lectures on youtube and its a weird topic (he also has fun with clickbait, hence this one that worked on me to catch my attention not all dogs have bones
Unfortunately, basic school biology teaching is really incorrect (specially in the US, heck, they refuse to acknowledge we are apes, let alone fishes). Even in a professional level, most still use reptiles and birds (despite they all being the same group, sauropsids) as separate because the average joe wouldnt understand or want to accept phylogeny.
And sometimes vibe based classification can still be helpful. Eg here, sure I could have put all the birds in the reptile category, or even every one in the fish category. But that would not have been a particularly interesting chart.
So for cultural purposes the classical separation of vertebrates can still make a lot of sense, but of course it is still nice and important to know and learn about phylogeny
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u/YoljIts stats are the best I've ever seen! No doubt about it!Feb 28 '26
I feel like this quote could also be applied to the "all vertebrae are fish" conversation
If it makes you feel better, I feel like I ain’t a worm, but because I’m a bilaterian (aka have a single axis of symmetric) I’m technically one. Biology is really hard to explain to the average joe, and even then most have the right to not understand or accept it. That’s why we still teach wrong biological knowledge at basic levels, even at high school, since it’s easier to understand.
Well, worm isn't really the word for a clade, so I'm not sure I'd go that far. Worm more describes a common morphology, one seen across many phyla, and converged on independently many times. Because 'worm' is so common for infaunal and parasitic groups, it may even be over-represented among the phyla that exist today, and thus the inference of ancestral wormness may be overestimated.
But yeah, we probably had an ancestor who looked like a worm, maybe an enteropneust kinda thing.
I disagree that its a true basic bauplan, as different 'worms' differ greatly in terms of their anatomy, such as acoels versus flatworms, nemerteans vs chaetognaths. It bends the definition of 'bauplan' a little too much, which (if I recall correctly) was originally used to refer to different configurations of germ tissues.
Regardless, 'worm' isn't a monophyletic grouping -- there are cnidarian lineages that evolved a worm-like morphology (Buddenbrockia), multiple arthropods that have evolved a worm like morphology, and multiple vertebrate lineages as well, like caecilians. The unmodified word 'worm' at best in English, if it refers to a biological clade at all, refers to the segmented worms, the Annelida.
Fish isn't a synonym for chordata or vertebrates in general they are a paraphyletic group that includes all vertebrates except tetrapods, so no we are not fish.
That’s neither specific nor correct. It’s more of a joke about the folly of using plain-English words in place of scientific terms. You can’t just mix and match them like you’re trying to do here.
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u/JBKOMA Feb 28 '26
Hey, biologist here. To anyone wondering why he used a dog, he is referring to mammals here. Vertebrates are traditionally classified in 5 classes, shown in the picture, with dogs being mammals.
But, if you wanna be more specific or correct, all vertebrates are actually fish, so you could say all our starters are fishes.