If the co -mammals of the CO2-In content increases, get panic and struggle to air because this indirectly indicates that the oxygen becomes scarce to breathe. In addition to this sign, seals apparently also have a second breathing alarm: the marine mammals can directly feel how much oxygen their blood contains, as biologists have found in an experiment. Thanks to this sensitive oxygen sensor and its reports to the brain, the seals can stay under water for longer when diving and reappear in good time before drowning. It is still unclear whether other marine mammals such as whales or sea lions also have such a secret weapon.
The bodies of marine mugs such as dolphins, whales and seals are well adapted to life in the ocean. Over time, they have developed a number of properties to survive in the water and survive even long and deep dives. Among other things, the animals have developed various methods to use oxygen (o2) to save and tolerate low oxygen values. This allows you to stop the air for a long time. Nevertheless, they regularly need fresh air to breathe and have to appear so as not to suffocate.
Most mammals cannot perceive the oxygen circulating in their blood directly, but only the carbon dioxide (CO2) in the blood. When the CO2-T content is increased, this indirectly indicates a low oxygen content. As with us humans, this creates discomfort to panic and a kind of “air hunger”. You then try to get air.
Robben react to changed oxygen and co2-Salary
This mechanism is sufficient for most land mammals, but also protects marine mammals sufficiently from drowning? Or can you possibly also perceive the oxygen in your blood directly? Researchers about Chris McKnight from the University of St Andrews in Scotland have now examined this. For this purpose, the biologists analyzed in six wildly caught cone seals (Halichoerus Gypus) whether this fluctuating oxygen and co2-perceive values in your blood and adapt your diving behavior. The researchers exposed the seals in a “breathing chamber” different air mixtures and then observed their hunting behavior under water in a test environment.
The observations showed that there is actually a direct connection between the oxygen content of the inhaled air and the diving time of the seals. In normal air in the breathing chamber, the animals dipped an average of around four minutes. If the inhaled oxygen content was only half as high, the seals ended their dives an average of 27 seconds earlier and also remained for 53 seconds longer to breathe. However, if the oxygen content was more than twice as high as normal, the seals remained under average for 14 seconds longer.
The co2-Stensed in the breathing chamber, on the other hand, surprisingly had no influence on the duration. The seals did not stay shorter under water, even if the CO2-Concentration was 200 times higher than in normal air, as McKnight and his team found. However, the seals of the seals then took longer: they stayed in the air chamber for 73 seconds longer before leaving for a new dive.
Oxygen sensors protect against drowning
McKnight and his colleagues conclude that bowling seals not only the CO2-Content, but also the oxygen content in your blood can perceive directly. This enables you to regulate your diving time accordingly – although you are primarily responding to the oxygen content and less to the CO2-Salary. “Robben can regulate their diving behavior so that they avoid the arterial o2-Pliegel values reached that cause severe neurological damage and lead to drowning, ”write the marine researchers.
The biologists suspect that this oxygen detection is based on the unusually sensitive chemoreceptors in the carotid arteries of the seals, which are known from previous studies. These sensors forward the signals via nerves to the brain and solve with too low o2-Wind alarm. In contrast, the CO seem2-Id receptors in the veins of the seals or the neurons that forward their signals to react weaker than with other mammals, according to the researchers.
McKnight and his colleagues suspect that other marine mammals also have this or similar abilities for oxygen perception, since their body has also adapted to long dives in the course of evolution. Whether and like other types of seals, sea lions, vision cows, whales or dolphins feel oxygen, follow -up studies must now show. They should then also clarify why these skills are missing in agriculture. So far, it is unclear whether this sensor has only arisen among marine mugs or whether the common ancestors of marine mugs and land -living mammals already had such a sensor. Then the land mammals could have lost this oxygen sense over time.
Source: Chris McKnight (University of St Andrews) et al., Science, Doi: 10.1126/science.adq4921