The Mystery of the Weddell Seal's Long Diving (Excellent Diver)

The Antarctic Weddell seal is also an excellent diver. It can dive to a depth of 600 meters for as long as an hour. What is the secret of such deep and long dives? Scientists conducted research in laboratory simulation sites and found that the physiological functions of Weddell seals change greatly during diving to adapt to the needs of diving.

A seal good at diving

When diving, the Weddell seal's heart beat immediately dropped from 55 to 15 beats per minute, and the blood flow in the heart dropped from 40 liters to 6 liters per minute. Most other organs only receive 5 to 10% of normal blood volume, but blood pressure remains normal at 160 mm Hg.

Blood sugar drops significantly when diving, and continues to drop for the first 5 to 10 minutes after surfacing, but cardiac function is greatly improved at this time. Due to the inability to breathe during a dive, the oxygen stored in the body is almost exhausted soon, and glucose can only be metabolized into lactic acid through anaerobic glycolysis. Therefore, the concentration of lactic acid in the blood is very high, up to 3 times the normal value. The lactic acid concentration dropped rapidly after floating. The energy required for descent is supplied by lactic acid.

The metabolism of the lungs is slowed down and lactic acid can be absorbed. This is different from normal times, when seals' lungs use glucose to metabolize.

The metabolism of the brain during diving is not yet clear. If lactic acid is also used, then the metabolism of glucose in the brain is 8 times higher than before to meet the needs; if not, it means that the brain's need for energy can be satisfied without oxygen. need. In fact, after 70 minutes of diving, the brain consumed only 33% of the total sugar.

The strange thing is, where does so much lactic acid come from? The brain and lungs cannot make lactic acid; it must come from somewhere else in the seal's body. Experiments have shown that lactic acid comes from muscles and skin because blood flow in these parts is very low, accounting for only 15%. Due to lack of blood and lack of oxygen, these organs can only perform anaerobic metabolism and produce lactic acid. However, the energy produced by anaerobic metabolism is very small. No wonder those organs with low free flow consume so much glucose to produce lactic acid.

Weddell seal brains consume very little oxygen, which is very beneficial for diving. The blood of Weddell seals contains 1,000 milligrams of oxygen, and the brain uses only 3 to 4% of the blood oxygen in 70 minutes, while the human brain uses 90% of the blood oxygen in the same time. A Weddell seal's heart uses 14% of its oxygen in 70 minutes, compared with 57% for a human heart. Judging solely from the oxygen consumption of the Weddell seal's brain and heart, it also has the potential to extend dive times.

Contrary to humans, the Weddell seal’s head is pitifully small, only about 5% of the human brain. It is not unreasonable for such a huge creature to have a small head that is less than 1/1000 of its weight. This may be one of the secrets why Weddell seals are suitable for deep and long dives.

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