Monotremes are mammals, yet do not share the property of giving live birth.
“Hair… may be greatly reduced in the Cetacea (i.e. dolphins), where it is found as a few scattered bristles about the lips or often present only in the young.” W. J. Hamilton, American Mammals.
Heterocephalus glaber, the naked mole rat, is a mammal despite being poikilothermic.
As DanArmak notes, mammals are explicitly not the set of all species fulfilling a particular set of (external) criteria. They are defined by descent.
To the extent that this is useful, great. My point was merely that there is no external fact of the matter that requires drawing the boundaries where they currently are.
So when “ordinary people…get it wrong” by believing that dolphins are fish, it’s a little hard to blame them.
Monotremes are mammals, yet do not share the property of giving live birth.
And many decidedly non-mammal animals do give live birth. Wikipedia lists “scorpions, some sharks, some snakes, [...] velvet worms [and] certain lizards”.
What exactly do you mean when you say they believe that dolphins are fish? The question isn’t about what to call a fish.
If they believe dolphins are like tuna in that they live entirely in the sea, have no hands and feet, swim with a thrashing tail, and eat other fish, then they are right.
And if they believe dolphins are like tuna in that they breath through gills and lay single-cell eggs into the water which grow into baby fish, then they are wrong. And I’d happily blame them for being wrong, because these are things that would be easy to get right with a little observation.
I’m suggesting that people see dolphins sharing the (easily-observable) characteristics they do with tuna and aren’t especially interested in the respiratory or reproductive aspects—particularly because the category of “air-breathing fish” is wrong in some sense by construction.
They are also wrong on the biochemical differences, but insofar as fish are pretty much just “all the animals in the sea” to the general public, I’d say the scientific and the popular use of the word probably diverge.
Perhaps I’m being too much of an economist, but I figure that the actual need for most people to know most of these biological details is limited, and the fuzziness in the popular use of the word arises from a low-effort sweep of the observables.
For people who don’t care in the least about dolphins (or fish), it makes sense. I shouldn’t have assumed everyone shares a minimal interest in zoology.
Monotremes are mammals, yet do not share the property of giving live birth.
“Hair… may be greatly reduced in the Cetacea (i.e. dolphins), where it is found as a few scattered bristles about the lips or often present only in the young.” W. J. Hamilton, American Mammals.
Heterocephalus glaber, the naked mole rat, is a mammal despite being poikilothermic.
As DanArmak notes, mammals are explicitly not the set of all species fulfilling a particular set of (external) criteria. They are defined by descent.
To the extent that this is useful, great. My point was merely that there is no external fact of the matter that requires drawing the boundaries where they currently are.
So when “ordinary people…get it wrong” by believing that dolphins are fish, it’s a little hard to blame them.
And many decidedly non-mammal animals do give live birth. Wikipedia lists “scorpions, some sharks, some snakes, [...] velvet worms [and] certain lizards”.
What exactly do you mean when you say they believe that dolphins are fish? The question isn’t about what to call a fish.
If they believe dolphins are like tuna in that they live entirely in the sea, have no hands and feet, swim with a thrashing tail, and eat other fish, then they are right.
And if they believe dolphins are like tuna in that they breath through gills and lay single-cell eggs into the water which grow into baby fish, then they are wrong. And I’d happily blame them for being wrong, because these are things that would be easy to get right with a little observation.
I’m suggesting that people see dolphins sharing the (easily-observable) characteristics they do with tuna and aren’t especially interested in the respiratory or reproductive aspects—particularly because the category of “air-breathing fish” is wrong in some sense by construction.
They are also wrong on the biochemical differences, but insofar as fish are pretty much just “all the animals in the sea” to the general public, I’d say the scientific and the popular use of the word probably diverge.
Perhaps I’m being too much of an economist, but I figure that the actual need for most people to know most of these biological details is limited, and the fuzziness in the popular use of the word arises from a low-effort sweep of the observables.
For people who don’t care in the least about dolphins (or fish), it makes sense. I shouldn’t have assumed everyone shares a minimal interest in zoology.