Nah, phylogenetically speaking, all descendants of fish must also be fish, by definition. Therefore, “being cold blooded” cannot also be a criterion (not that it would work anyway since tuna are warm blooded, BTW, and nobody would argue tuna aren’t fish).
The “living wholly in water” criterion actually works, though: land-fish (e.g. humans) live inside a bag of water that we carry with us.
Of course there’s such a thing as a fish! A fish is any swimming vertebrate (or its descendant), such as a tuna, or a duck, or a human.
Being cold blooded and living “wholly in water” are also requirements.
Nah, phylogenetically speaking, all descendants of fish must also be fish, by definition. Therefore, “being cold blooded” cannot also be a criterion (not that it would work anyway since tuna are warm blooded, BTW, and nobody would argue tuna aren’t fish).
The “living wholly in water” criterion actually works, though: land-fish (e.g. humans) live inside a bag of water that we carry with us.
You believe in cladistics or you don’t, cowards!