Natures wonders: goldfish survive frozen winters (Introduction)

by David Turell @, Saturday, August 12, 2017, 18:22 (122 days ago) @ David Turell

The ponds they live in during winter in Europe freeze over, so they have found a way to alter their metabolism, from anaerobic lactic production. which we use, although briefly, to an alcohol end product which can be defused away:

https://www.newscientist.com/article/2143579-goldfish-go-months-without-oxygen-by-makin...

"Goldfish and their wild crucian carp relatives can survive for five months without breathing oxygen – and now we know how. The fish have evolved a set of enzymes that, when oxygen levels drop, ultimately helps convert carbohydrates into alcohol that can then be released through the gills.

"For most animals – including humans – a lack of oxygen can be fatal within minutes. We can metabolise carbohydrates without oxygen, but the process generates toxic lactic acid that quickly builds up in our bodies.

"On the face of it, this should pose a big problem for crucian carp. They live in ponds and lakes in northern Europe and Asia that freeze over in winter, so the fish have to survive for months without oxygen until the ice melts in spring.

"But the carp – and their close relative the goldfish – have developed a workaround. When they metabolise carbohydrates anaerobically, the end product is not lactic acid but alcohol, which is easier to remove from their bodies.

"Goldfish and their wild crucian carp relatives can survive for five months without breathing oxygen – and now we know how. The fish have evolved a set of enzymes that, when oxygen levels drop, ultimately helps convert carbohydrates into alcohol that can then be released through the gills.

"For most animals – including humans – a lack of oxygen can be fatal within minutes. We can metabolise carbohydrates without oxygen, but the process generates toxic lactic acid that quickly builds up in our bodies.

"On the face of it, this should pose a big problem for crucian carp. They live in ponds and lakes in northern Europe and Asia that freeze over in winter, so the fish have to survive for months without oxygen until the ice melts in spring.

"But the carp – and their close relative the goldfish – have developed a workaround. When they metabolise carbohydrates anaerobically, the end product is not lactic acid but alcohol, which is easier to remove from their bodies.

***

"The study suggests this adaptation evolved 8 million years ago in the common ancestor of carp and goldfish, through a process known as whole-genome duplication. This is when an organism ends up by chance with an extra set of its genes, which can then be repurposed to take on new functions.

"By making alcohol, crucian carp and goldfish can survive where no other fish can, meaning they can avoid predators or competitors. But their adaptation does mean that the fish spend most of the winter with blood alcohol levels of roughly 55 milligrams per 100 millilitres – which Berenbrink points out exceeds the drink-driving limit in some northern European countries."

Comment: It is difficult to understand how this adaptation developed by chance through an evolutionary process. If a pond freezes over completely a fish cannot move water through its gills, and the way water freezes top down is faster than the genome can self invent over generations. it must be an all-at-once saltdation.


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