Divers-record: how whales survive at great depths

© Depositphotos / alonesdjКит under waterDivers-record: how whales survive at great depths© Depositphotos / alonesdj

Out of all mammals, only sperm whales, southern elephant seals and luvaridae whales dive to a depth of over a kilometer. Their bodies are perfectly adapted to high pressure and cold that prevail in the blue abyss.

Unfriendly abyss

The sun warms only the surface of the oceans and seas. Already at a depth of several meters the water gets a few degrees colder. And with three to four kilometers, the temperature is lowered to 0°C and even lower, depending on the degree of salinity and the latitude.

However cold the surface is not the biggest problem for living beings. Much worse than the monstrous pressure of the mass of water. On earth we experience a pressure of one atmosphere. Given that the density of water is approximately 800 times greater than air, every 10 metres of depth increases pressure by one atmosphere. Therefore, three kilometers in the ocean thicker all living and non-living is under pressure of 300 atmospheres.

Previously, scientists believed that the person literally flatten at a depth of several kilometers. Later it turned out that the danger only places where the fabric is in contact with the cavities of the middle ear and other air sinuses in the head, as well as light. Even small pressure differences can cause damage and high blood pressure simply crush these organs.

Whales stack light

Some marine mammals have adapted to withstand the enormous pressure and calmly descend to great depths to hunt, from time to time rising for a breath of air. Monitoring with sonar showed that sperm whales and southern elephant seals dive to two kilometers for 20-60 minutes. Luvaridae whales can dive almost three miles.

When diving cetaceans almost does not involve the muscles actively consuming oxygen: animals just slip down — literally drowning due to the reduced lung volume. Actively move the whales begin, only seeing the victim. And the whales get oxygen in the muscles and blood. No wonder her specific volumes of marine mammals in three to four times more than the person 200-250 milliliters per kilogram of mass.

Oxygen transport is also enhanced in cetaceans: concentration of hemoglobin (O2 carrier), they are two times higher than in humans, so the colour of their blood is dark red, almost black. And the content of myoglobin, a protein for storing oxygen in the muscle exceed human 10 times. If we consider that the molecules of myoglobin generally tend to stick together (which causes diseases such as diabetes and Alzheimer’s disease) for a person with such a concentration would be fatal. But in the body of cetaceans molecules keeping the protein oxygen positively charged, so repel each other, preventing adhesion.

When diving, deep-sea mammal stops digestion, kidneys and liver are working limited. To save oxygen, they reduce the heart rate. For example, the heart of Weddell seals diving to a depth of over 700 metres, beating only four times a minute.

CC BY-SA 3.0 / Samuel Blanc / the Weddell seals when immersed heart beats only four times per minuteDivers-record: how whales survive at great depthsCC BY-SA 3.0 / Samuel Blanc / the Weddell seals when immersed heart beats only four times per minute

As for the cold, sperm whales and whale is protected by a thick layer of subcutaneous fat, the constant movement and heat exchange between arterial and venous blood. And vision most mammals, hunting under water, not particularly necessary — they are guided by echolocation, producing high frequency sounds and detecting their reflection.

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