Alcohol is a solution, chemically speaking. But in the goldfish's case, it literally is.
Bizarre as it may sound, goldfish can go months without oxygen by making alcohol that can be released through their gills. Their wild crucian carp relatives have evolved a set of enzymes that when oxygen levels drop, it helps convert carbs into alcohol.
Because we are humans (and humans as we are, we have done the stupidest things with our bodies -- like holding our breath for more than a minute and ending up red and panting and crucially grasping for air the moment we realize we're eventually going to kill ourselves if we don't stop), we are now aware that a lack of oxygen can be fatal within minutes, like animals. And like animals, we, too, can metabolize carbohydrates without oxygen, however the process produces toxic lactic acid that may abruptly and quickly build up in our bodies.
It's different with the carp and their close relative (the goldfish!), however, as they have developed a workaround during the winter: when they metabolize carbs anaerobically, the generated product is not lactic acid, but alcohol, which is something that's easier to remove from their bodies.
Now I can't stop imagining fish cops chasing all these alcoholic goldfish. "Sir, you are arrested for swimming under the influence."
Michael Berenbrink of the University of Liverpool in the UK -- a member of a team led by Cathrine Fagernes at the University of Oslo, Norway and his colleagues have discovered that the fish have their own specialized alcohol-production system (damn), which comprises a modification of a set of the enzymes that networks their energy-rich carbohydrates into -- cue gospel music -- mitochondria, the powerhouse of the cell (yey, fifth grade).
The fish gain a second set of the enzymes during their evolution, which, in turn, helps the metabolic products convert into alcohol when oxygen levels drop.
Fagernes says that other species usually die long before the decrease in oxygen availability is even a problem for the crucian carp; the fish gets rid of the dangerous end products by using this method.
"This only goes to prove how essential it is to understand simple mechanisms for surviving anoxia (the technical term for the absence of oxygen)," says William Martin of the University of Dusseldorf in Germany.
This study suggests that the goldfish's adaptation evolved over 8 million years ago in the common ancestor of carp and goldfish through a process known as whole-genome duplication, a process that occurs when an organism ends up with an extra set of its genes by chance -- which then can be repurposed to take on new functions. Like a mutant.
So if you're planning tequila goldfish, remember, they can pretty much beer five months without oxygen. Dying in that way isn't in their vodkabulary after all. You can even look it up in whiskeypedia.
Alcohol-related jokes in moderation, am I right?
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