14 Aug '17 10:07>6 edits
https://phys.org/news/2017-08-scientists-reveal-goldfish-alcohol-survive.html
so they can survive for months at a time without any oxygen in the water and do so by their cells gaining energy from carbohydrates not by aerobic respiration of them but rather by anaerobic breakdown of them with the end waste product not being CO2 but rather ethanol.
"...crucian carp, can survive for days, even months, in oxygen-free water at the bottom of ice-covered ponds.
During this time, the fish are able to convert anaerobically produced lactic acid into ethanol, which then diffuses across their gills into the surrounding water and avoids a dangerous build-up of lactic acid in the body.
The molecular mechanism behind this highly unusual ability, which is unique among vertebrates and more commonly associated with brewer's yeast, ....
...
"During their time in oxygen-free water in ice-covered ponds, which can last for several months in their northern European habitat, blood alcohol concentrations in crucian carp can reach more than 50 mg per 100 millilitres, which is above the drink drive limit in these countries.
"However, this is still a much better situation than filling up with lactic acid, which is the metabolic end product for other vertebrates, including humans, when devoid of oxygen."
..."
This finding makes me think it is perfectly possible for a complex animal species to evolve to always live without free oxygen and complete its entire reproductive life cycle without once being exposed to free oxygen.
It also makes me think it would eventually be possible to genetically modify humans to live and breath on another planet without any free oxygen in the planets atmosphere; a possible practical alternative to more expensive and time consuming terraforming of the whole planet. But such humans would have to be at the same time be genetically modified with neurology that is such that there is no intoxicating effects on that neurology from constant exposure to massive ethanol concentrations else they will be poisoned to death (or, if not actual death, at least dire totally unacceptable consequences for there health) by their own waste product of ethanol.
so they can survive for months at a time without any oxygen in the water and do so by their cells gaining energy from carbohydrates not by aerobic respiration of them but rather by anaerobic breakdown of them with the end waste product not being CO2 but rather ethanol.
"...crucian carp, can survive for days, even months, in oxygen-free water at the bottom of ice-covered ponds.
During this time, the fish are able to convert anaerobically produced lactic acid into ethanol, which then diffuses across their gills into the surrounding water and avoids a dangerous build-up of lactic acid in the body.
The molecular mechanism behind this highly unusual ability, which is unique among vertebrates and more commonly associated with brewer's yeast, ....
...
"During their time in oxygen-free water in ice-covered ponds, which can last for several months in their northern European habitat, blood alcohol concentrations in crucian carp can reach more than 50 mg per 100 millilitres, which is above the drink drive limit in these countries.
"However, this is still a much better situation than filling up with lactic acid, which is the metabolic end product for other vertebrates, including humans, when devoid of oxygen."
..."
This finding makes me think it is perfectly possible for a complex animal species to evolve to always live without free oxygen and complete its entire reproductive life cycle without once being exposed to free oxygen.
It also makes me think it would eventually be possible to genetically modify humans to live and breath on another planet without any free oxygen in the planets atmosphere; a possible practical alternative to more expensive and time consuming terraforming of the whole planet. But such humans would have to be at the same time be genetically modified with neurology that is such that there is no intoxicating effects on that neurology from constant exposure to massive ethanol concentrations else they will be poisoned to death (or, if not actual death, at least dire totally unacceptable consequences for there health) by their own waste product of ethanol.