[Animals] Fish that would test positive for a breathalyzer test and rodents that are allowed to die

[[M]anuel]

link: https://www.abc.es/ciencia/abci-peces-darian-positivo-control-alcoholemia-y-roedores-dejan-morir-202109241105_noticia.html

 

Dormouse and goldfish have achieved two of nature's most fascinating evolutionary adaptations

 

 

 

One of the most elegant rodents in our Iberian forests is the dormouse (Eliomys quercinus), which is found halfway between the squirrel and the field mouse. Etymologically, its name derives from the Greek 'eleos' which means to wander and 'mys', mouse; while 'quercinus' is of Latin origin and refers to oak.

 

Its vernacular name is due to the characteristic of the presence of a blackish strip of hair located in the eye area - like a mask-, covering part of the face and extending to behind the ears.

 

To this must be added the other singularity, that of having one of the longest hibernation periods in the animal kingdom, and that is that the dormouse disappears from the forest from mid-autumn to mid-spring. In this way we could say, without fear of exaggeration, that this small mammal is a 'sleepyhead with a mask'.

 

Six beats per minute

 

During hibernation the dormouse can lose up to half the weight it had at the beginning, for this reason, and in order to accumulate as much fat as possible, it spends all summer gobbling hazelnuts, blackberries, raspberries, seeds, earthworms and crickets.
 

With the thermal drop, it curls up in its burrow, literally curls into a ball, and begins one of the most placid winter dreams. This requires that your metabolism performs a series of adaptations: breathing becomes practically imperceptible, the heart rate slows down - it goes from three hundred beats per minute to just six -, the brain is 'disconnected' performing minimal functions, and kidneys stop filtering waste products.

 

In this way, this mammal manages to reach a metabolic situation that puts it on the edge of death, but that protects it from the rigors of winter. Of course, with the arrival of the first spring rays, its metabolism is 'reset', the dormouse stretches and begins to run through the Iberian forests.

The secret is in the alcohol

In situations where there is no oxygen and intense exercise is required, the body of most animals, including humans, resorts to alternative anaerobic pathways.

 

One of them, the most evolutionarily successful, is called glycolysis (from the Greek 'glycos', sugar, and 'lysis', breakdown) and consists of converting glucose into fatty acids, thus obtaining ATP molecules.

 

The B side of this metabolic reaction is that lactic acid is generated, a compound that, if it reaches certain concentrations in the circulatory stream, can cause the death of the individual.

 

Some animals are condemned, during the winter months, to suffer a prolonged situation of anaerobiosis, requiring glycolysis as the only energy source, at the risk of generating high levels of lactic acid.

 

Among these animals are, for example, goldfish (Carassius auratus), better known as Goldfish. When the lakes in which they live freeze and oxygen disappears to these fish, we are left with another option that enters anaerobiosis.

 

Fortunately for them, about eight million years ago, their ancestors devised a strategy that allows them to avoid avoiding death from metabolic acidosis, which basically consists of converting lactic acid into alcohol.