How Anaerobes Breathe
Still more primitive animals, primarily bacteria, have no haemoglobin and are therefore unable to actively extract oxygen from their surroundings. However, they are often doomed to environments where there is little or no oxygen at all. Nevertheless, these creatures are quite happy to reconcile themselves to an absence of oxygen. This led to their being named anaerobes, which means ‘one who lives without air’.
How do anaerobes manage to live without air? Not so long ago this has seemed to be a puzzle that could not be solved. Now we know that they do need oxygen all the same. Instead of extracting oxygen from the atmosphere the anaerobes simply take it from organic substances. Some bacteria even extract oxygen from inorganic substances, using nitrites and sulphites for the purpose.
Anaerobes breathe by oxidizing the products of metabolism without using additional oxygen and are quite content with the amount already present in the substance being oxidized. For, when a substance is oxidized, it makes no difference whatsoever whether oxygen is added to, or hydrogen removed from it.
Filed under oxygen | Tags: anaerobes, bacteria, breathing, extract oxygen, haemoglobin, oxygen | 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)