Are pharyngeal and cutaneous breathing possible for an aquatic mammal?

I'm working on a setting with merfolk that I'd prefer to be fully mammalian. However, they have underwater cities and I find that hard to believe for a species that needs to surface every few hours at most to breathe. So, I was wondering if pharyngeal and cutaneous respiration similar to what softshell turtles are capable of would be plausible for a mammalian species. Would this method of breathing capable of providing the amount of oxygen necessary to maintain a warm-blooded metabolism? Are there any other concerns that would make this unrealistic for a mammal?

posted almost 7 years ago

Cowrie‭

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