Poisoned by Oxygen
There was a good reason for the scientists’ interest in oxygen poisoning. The problem was how to facilitate the work of divers. A man can survive in an atmosphere of pure oxygen for about twenty-four hours. If he breathes oxygen for longer than that, pneumonia ensues and, strange as it may seem, death due to asphyxia, which is a shortage of oxygen in the most important organs and tissues. A man can endure a pressure of two to three atmospheres not longer than one and a half to two hours. Then he becomes intoxicated with oxygen, loses coordination of movement, and suffers from mental distraction and loss of memory. If the oxygen pressure exceeds three atmospheres, convulsions will soon follow causing death.
Oxygen proves even more poisonous for animals which live where there is a critical lack of oxygen. This is how ascarides living in human intestines are combated. Oxygen is fed into the intestines, causing no danger to the man himself, but surely killing the parasites.
An excess of oxygen is not only detrimental to animals, but also to plants. It is interesting that, although plants saturate the atmosphere of our planet with oxygen, the Earth’s atmosphere is not good for them. They are rather short of carbon dioxide and, strange as it may seem, there is too much oxygen for them. According to recent investigations not only the usual concentration of oxygen but even as little as two per cent, that is one-tenth of what is to be found in the atmosphere, considerably retards photosynthesis. This means that plants have created an atmosphere quite unsuitable for themselves. Had there been less oxygen they would have grown and developed more rapidly.
Filed under oxygen | Tags: breathing, carbon dioxide, excess of oxygen, lack of oxygen, oxygen, oxygen poisoning, oxygen shortage | Comment (0)Struggle for Breathing in Ecological Niches
There are many places on the Earth which have little or no oxygen. In most cases, living creatures themselves are responsible for this, bacteria being especially heavy consumers of oxygen. One milligram of bacteria is able to consume 200 cubic millimetres of oxygen per hour. It should be pointed out that a working muscle of comparable weight will, during the same period, use only 20 cubic millimetres of oxygen and only two and a half cubic millimetres when relaxed. Owing to the activities of bacteria and the larger microorganisms many nooks on our planet are becoming quite unsuitable for life, and so animals have to be more inventive to settle in such ecological niches.
One such niche is successfully inhabited by electric eels. These large fish live in the swamps and small rivers of South America. During the rainy season the rivers become turbulent, and the swamps are flooded with streams of muddy water. These streams are rich in oxygen and the dwellers of the underwater kingdom can breathe easily. But, during the drought which follows the rainy season, the rivers quickly become shallow, forming small lakes with narrow stretches of water between them, and the marshes begin to dry out. In the shallow pools heated by the tropical sun the plants rot and the microorganisms multiply rapidly, consuming oxygen at a greater rate than it diffuses from the air. Thus, breathing becomes more and more difficult for all the water-dwellers, dyspnoea develops.
But the electric eel feels tine and does not seem to sutler from the lack of oxygen. What is more, food is plentiful. All the inhabitants of the disappearing pools are attracted to the place where the eels have settled. We shall have something to say about animal power stations later, but now we shall only point out that the electric eels do not hunt for their prey. Liquid mud is brown like coffee dregs in which you cannot even see the tip of your nose. It is obvious that one cannot catch anything there, except quite by chance. The eels kill their prey with powerful electric shocks, without even looking or trying to see what kind of creature it is.
Filed under oxygen | Tags: bacteria, electric eel, lack of oxygen, muscles, oxygen, rich in oxygen | Comment (1)