Why don't fish freeze in cold water?

Why don't fish freeze in cold water?

Almost all fishes are cold-blooded animals

From the course curriculum we already know that fish are cold — blooded creatures. This means that their body temperature equals the temperature of the water in which they swim. This begs the question: how fish that swim in the cold waters of Antarctica, not die of hypothermia? Because water temperature in these regions is quite extreme and rarely rises above 4 degrees Celsius. Given that the freezing point of sea water is -2 degrees, while sailing across the icy waters, fish also have to turn into icicles. As it turned out, in the blood of some species contains a kind of antifreeze — a substance that does not freeze at subzero temperatures. How the fish adapt to extreme conditions of Antarctica, it was found in the study conducted with the support of German car manufacturer Volkswagen.

Usually in the Antarctic waters swim the so-called nototheniidae fish. If you believe the calculations of scientists, today there are about 156 species. Many of them are eaten and even imported to Russia. For example, in sales it is possible to find sea bass (Patagonotothen ramsayi) or ice fish (for Champsocephalus gunnari). The people of the Soviet era can also remember that the market can be found a marble notothenia (Notothenia rossii), and another couple of fish caught from .

Ice fish (Champsocephalus gunnari)

As mentioned above, nototheniidae fish live in waters where the temperature almost never rises above 4 degrees Celsius. Although recently the weather in the coldest region of our planet is downright cranky. In the beginning of 2020 I published the news that in Antarctica have been recorded to 18.3 degrees Celsius. It certainly influenced the condition of the water and inhabiting fish in it, apparently, felt fine.

But let's go back to the fact that most of the time fish spend in cold water, at a depth of about 1500 meters. In the study of fish, scientists have found that turning their bodies into blocks of ice impeded by special proteins, known as glycoproteins. Back in the mid-twentieth century, scientists discovered that these substances inhibit the process of freezing of liquids in 200-300 better than salt, which in winter cover the roads of the cities of our country. It's kind of antifreeze, which allows the fish to withstand extremely low temperatures.

Notothenioidei fish, there are about 156 species

Life-Saving fish proteins are not only inside their body, but have water external influence. In the course of scientific work, the researchers found that the presence of glycoproteins in the blood of the fish, surrounding their bodies, the water molecules begin to move slower, which prevents the formation of ice crystals. That is, fish do not have the risk to turn into blocks of ice is just impossible.

the Interaction of fish and water — a much more complex process than previously thought.

But resistance to the cold waters have not all fish. One of them is one of a kind red-blooded fish opah (Lampris guttatus). In the beginning of this article I mentioned that all fish are cold-blooded and their body temperature depends on water temperature. So, Krasnoperov opah — the exception to this rule. In 2015, the American scientists have found out that their body temperature is usually 5 degrees above the water temperature. And all because the fish continuously heats itself, actively moving their fins. And the heat retention inside the body contributes to their thick fat layer.

the body length of the red opah can reach two meters.

On the subject of unusual inhabitants of the world ocean also suggest reading material on . Some of them you already know well — for example, you've probably seen pictures of fish-drop. Looking at it you'd think that's the saddest creature in the world. But you still hardly know about the existence of Pisces-the moon, the sea ragpicker and other creatures, so you can start reading right now!

Source: scienews.com

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