Perfect apnoea swimmers

For how long can you hold your breath? If you are good you may even hold it for a minute or two. However some sea animals can reach an hour or more. This is the case of cetaceans that are mammals, and breathe with their lungs, and therefore must reach the surface in order to breathe exactly like us humans. However particular mechanisms help them to prolong the time of apnoea (i.e. their capacity to hold their breath), specially in species such as the sperm whale, that feed on giant squid, which can be found at great depths. In fact the sperm whales can reach depths below 2000 metres (a scuba diver with an oxygen supply generally does not exceed a depth of 40 metres when diving for fun) with apnoea lasting up to two hours. They have a high haemoglobin density (the protein that is present in the red blood cells that enables the transportation of oxygen), in the blood and myoglobin (a protein that is present in the muscles that can store oxygen) in the muscles : a high dose of these proteins therefore, means a great amount more of oxygen that is stored and therefore their capacity to hold their breath will be longer. These sea mammals are also able to slow down their heartbeat and to cut away less important organs from the blood stream, so as to supply oxygen where it is most needed, for example in the brain.

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