Subnivium: a secret world full of life under the snow

Each winter, snow covers much of the Northern Hemisphere.

Its mantle can extend over 40 million kilometers, generating, when the conditions are right, a vast and ephemeral ecosystem: the subnivium.

It is the name by which the small area that forms between the snow cover and the ground is known;

a space so well insulated thermally that it can remain stable around 0ºC for weeks, even if the outside temperatures drop below 20 or 30 degrees below zero.

For this, a layer of snow of about twenty centimeters must be formed that is not very dense.

The lighter and fluffier the better.

This increases its insulating capacity.

As the snow settles on the ground, warm air from the ground rises, turning the deeper layers of snow into air vapor.

When this condenses, it freezes to form the icy ceiling of a small space a few centimeters above the ground.

The subnivium is an extensive and complex ecosystem of small caves and corridors of fine ice that offer shelter to plants and animals.

Many species depend on their formation to survive the harsh northern winters.

More information

How does the bear survive during hibernation?

|

natural histories

Here it is possible to find beetles, springtails, spiders and even different types of flies active throughout the winter.

It doesn't matter that outside the temperatures have dropped below freezing and there are strong gusts of icy wind.

Under the snow, winter seems to have stopped.

There is no wind and the temperature is stable, although it is around the freezing point, it remains unchanged.

It's not a dark world, in fact, enough light can filter through the snow that mosses and evergreen shrubs continue to photosynthesize.

Some plants even flourish under the snow.

Shrews and mice also move under its vaulted tunnels.

Nor do weasels have any problem entering them to run after rodents, while foxes and wolverines may even plunge into the snow to nestle in the warmer bases of the subnivium.

A vast and ephemeral ecosystem: the subnivium, a small area between the snow cover and the ground, which offers shelter to plants and animals

A frozen forest in Germany.Heiner Machalett

Among the fallen leaves captured under the snow it is possible to find frogs hibernating, waiting for better times.

There is a series of frogs in North America that stand out for their extreme adaptation to cold.

While most frogs survive winters by hibernating deep in lakes or streams, where temperatures never drop below freezing, these frogs follow a radically different strategy.

One of them is

, which when winter comes huddles among the leaf litter under the subnivium, protecting itself from extreme temperatures, but not from the freezing point.

In fact, these frogs become little more than ice cubes for days.

Two-thirds of the water in their bodies can freeze without harm.

Surviving a freeze is not normal.

We are still far from being able to freeze to make intergalactic trips due to the dangers involved, although perhaps we can learn something from these frogs.

When a body freezes, ice crystals form that perforate blood vessels, cells dehydrate, fracturing their cell walls and disassembling their interior structure, in addition to the fact that once the blood has frozen, there is no way to transport oxygen and nutrients to vital organs.

For the vast majority of animals, frostbite causes immense internal damage and death.

Not for some frogs.

They can be frozen for up to eight months and come back to life in the spring.

A specimen of 'Lithobates sylvaticus', in Russia.getty

To do this, frogs produce large amounts of glucose in the liver as soon as the cold arrives.

This sugary solution is concentrated inside the cells, acting as an antifreeze that prevents dehydration of the cells and the formation of ice inside them.

On the other hand, the bloodstream is loaded with nucleoproteins that enhance the formation of ice, so when temperatures touch zero degrees, the liquids that surround the cells and vital organs freeze.

The animal is stiff.

For months they have no muscle movement.

His heart does not beat.

He doesn't breathe.

The eyes look white because the lens has frozen.

It is a block of ice carved in the shape of a frog.

But he is alive.

The frogs remain under the subnivium in a state of suspended animation.

You just have to wait for spring.

In the heat, first the heart will begin to beat, then the brain activity will activate and, finally, the limbs will move.

Just waking up will start walking to a suitable place to reproduce.

They will be the first amphibians to do so, long before other species.

It is not yet known what causes the heart to fire after being stopped for so long.

Or why they don't suffer the problems of diabetics when their blood levels reach levels 100 above normal.

Perhaps under the ephemeral ecosystem of the subnivium there are answers to diabetes, to the maintenance of organs for transplants or how to treat circulatory systems that have temporarily stopped after a heart attack or stroke.

You can follow

Subscribe to continue reading

Read without limits

Keep reading

I'm already a subscriber