Buckle your seatbelt – the term “drinking like a fish” is about to get way more apropos. Also, so is the Jesus fish on the back of your neighbor’s station wagon (if they still make station wagons?). Why? Because it turns out that about 8 million-ish years ago, certain species of fish evolved the ability to turn water into wine…or at least ethanol.
They probably taught Jesus how to do it, just saying.
Okay. Back to the fish.
The science: Certain fish that live in ponds that ice over for a significant portion of the year (meaning the water can no longer exchange oxygen with the air, leaving them nothing to breathe) have an evolutionary trick – they revert to anaerobic respiration, meaning they don’t need so much oxygen. But when they do that, they start to accumulate lactic acid in their muscles. In order to deal with this secondary issue, they produce an enzyme (pyruvate decarboxylase) similar to one found in brewer’s yeast, which allows the fish to convert lactic acid into ethanol. This enzyme is the first of its kind to every be found in vertebrates.
In layman’s terms: The fish can’t breathe normally in water devoid of oxygen, so they start breathing differently. The low or no-oxygen water creates a buildup of lactic acid (which happens when humans drown), and in order to lower those toxic levels, they have a special (additional) enzyme that changes the acid into alcohol.
Here’s an explanation from a real scientist, Dr. Michael Berenbrink of the University of Liverpool:
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 milliliters, 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.
Basically, it’s better to be drunk than dead, a sentiment that’s certainly hard to argue with.
The carp and the common goldfish share a common ancestor from around the time that the ability evolved (likely during an ice age), which is why they both exhibit the ability today. That sort of mass evolutionary ability is known in the world of biology as a whole genome duplication event.
Pretty neat, no?
I mean, I wish I could do that…
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