From what we know on Earth, all animals use the three forms of energy and for its consumption they use appropriate physiological systems (respiratory system and digestive system). This universality raises the possibility that the food chain as a mechanism for energy supply exists anywhere in the universe
Energy is the basic commodity that every animal and every plant needs, without it they will not survive. The three known forms of energy are gaseous energy, liquid energy and solid energy. Gaseous energy is the oxygen that all animals breathe (exclude anaerobic microorganisms). Liquid energy is the water that all animals drink and solid energy is all the plants and animals that are eaten by animals.
The basic division in terms of the use of solid energy is that there are animals that feed on plants, animals that feed on plants and animals, and animals that feed on animals. This pattern of using the solid energy is called the food chain and it is a concept "that describes the feeding relationships that exist between the participants of the biosphere. The first link in the chain is the plants that produce organic matter and are therefore the producers of the biosphere. The second link in the chain is the herbivores, who are called primary consumers, those who feed on plant eaters are called secondary consumers (like a spider that eats an ant) and those who feed on carnivores are called tertiary consumers (like an eagle that eats a snake)"1.
From what we know on Earth, all animals use the three forms of energy and for its consumption they use appropriate physiological systems (respiratory system and digestive system). This universality raises the possibility that the food chain as a mechanism for supplying energy exists anywhere in the universe where there is life, although we must take into account that there can be different variations here subject to the environmental conditions in which these life forms operate. There can be a planet where the percentage of vegetarian animals is very large compared to carnivorous animals and in another place, for example, the percentage of liquid energy needs is large compared to the percentage of solid energy needs. These variations must also be a result of the evolutionary processes operating there.
The biosphere as a system activates mechanisms to maintain a dynamic balance between the total number of animals and their active types within it, so that the number of animals does not increase too much, whether it is the whole complex or whether it is the animal species. An excess of vegetarian animals per unit area, for example, may lead to the elimination of vegetation, which will damage the base of the food chain and, as a result, also damage higher levels. An excess of predatory animals will oblige them in order to survive to prey on all the animals that are one level below them and hence, who will be left after a short time without sources of food, they will also die and the food chain will also be damaged at a higher level. This balance is a result of the percentage of animals out of the total number of individuals of a given species that die in a unit of time. The predatory animals serve as part of this mechanism. When they prey, animals of a lower rank "they prey only on the weak, the sick and the elderly - a custom that is strongly imposed on them by the fact that a healthy adult is usually able to escape or fight back - and thus they ensure that only the fit will continue to exist. If the adults, healthy and able-bodied of a species cannot escape or fight back, the entire species will quickly be doomed and another species will occupy its niche"2. This is therefore a very delicate balance in which the slight change that will occur will affect the animals at least on both levels, the level above them and the level below them.
Since life appeared on Earth, evolution has led to the diversification of the number of plant and animal species and the result is a large number of steps in the food chain. Therefore, next to the terms like primary consumers and secondary consumers, the term stairs that we mentioned earlier should be used. If, for example, we have several predators that are preyed upon by each other, then the number of steps is the same as the number of predators. If for example within the group of secondary consumers we have 4 predators Predator A, Predator B, Predator C and Predator D, Predator A feeds on an animal that feeds on plant food, Predator B feeds on Predator A, Predator C feeds on Predator B And predator D. feeds on crazy C. From this, the conclusion is required that over time, with the deepening of evolution and an increase in the extent of the differences between animals and plants, the food chain becomes more complex and sophisticated. Therefore, examining the complexity of the food chain on any planet that carries life, can give an indication as to the depth of the evolution that took place there and also an ability, albeit basic, as to the age of life on this planet.
Since the first step in the food chain is the vegetation, the second step should appear only with the appearance of the animals. From what is known on Earth, it seems that the food chain should have appeared at least in the Carboniferous period (360 million years ago), when huge forests of plants first appeared, at the same time or after them, amphibians began to spread, the first reptiles appeared and different groups of insects began to spread throughout the world3 . But the findings show that animals appeared earlier. An example of this is the jawless vertebrates that appeared in the Ordovician (505 million years ago)4. Since these vertebrates had to have food sources and if indeed there was no vegetation then, they had to rely nutritionally on animals of a lower rank than them. Since the origin of life, including the first animals, was in the sea, the conclusion is required that the food chain began at a very early stage in the development of life, even before there was vegetation and the environment in which it appeared was therefore the marine environment. As a result, the conclusion is required that the food chain does not have to start with plants, but with another biological factor, which constitutes the first step. This would imply different starting points for a food chain in other biological evolutions that found their place on life-bearing stars.
A food chain whose first rung is vegetation has a new element and that is that it operates mainly on land. Even if it exists in an aquatic environment, it is extremely limited. It is only possible up to that place where sunlight cannot reach. On Earth this is only possible up to a depth of 200 meters. This depth is a function of the planet's distance from the Sun. It could be that if the earth was closer to the sun (a distance where the sun's heat still allows the presence of water), an aquatic food chain based on marine vegetation could exist even at greater depths.
There have been several mass extinctions of animals on Earth. First at the end of the Ordovician period, second at the end of the Devonian period, third at the end of the Permian period, fourth at the end of the Triassic period and fifth at the end of the Cretaceous period5. This has one meaning and it is the interruption of the food chain and its renewed development, with the renewal of life. There is quite a bit of geological evidence for such a phenomenon. An example of this is the extinction that occurred about 240 million years ago, in the transition between the Permian and Triassic periods6. Possible explanations for this extinction are, for example, a powerful meteorite impact, which raised large amounts of dust that were dispersed in the atmosphere or volcanic eruptions on a global scale that resulted in the emission of amounts of ash and gases on a cataclysmic scale. In any case, the result was the same - the darkening of the earth's surface, slowing down and cessation of photosynthetic activity. The animals that feed on plants, lost their source of life and died as well, thus the entire food chain stopped as a whole. It was renewed only when the dust began to settle and the sun began to illuminate the earth again. Whether one of these explanations is true or both are true, this phenomenon can also happen on other life-bearing stars. In any case, the meaning is one, the food chain will be renewed only when the whole of life is also renewed.
Parallel to the food chain, there is an opposite food chain. This is the same food chain that decomposes the dead animals7. In the first step there are maggots of flies or insects (beetles and ants) that feed on the various parts of the carcass and break it down into smaller units. On the second level are even smaller animals, such as leeches that feed on the small units of the corpses. As these parts pass through their digestive system, they are broken down even further, and the parts secreted from the digestive system feed the creatures on the third level. Among the creatures found in this level are the fungi and they break down these parts into simple compounds which in turn are broken down into the inorganic starting materials by the bacteria found in the fourth and last level.
In light of the fact that life on Earth was accompanied by a number of extinctions, the possibility arises that this extinction actually created massive and sudden sources of food for all the animals in the opposite food chain, which allowed their rapid reproduction. With the renewal of life and the return to a mortality rate, if it can be called "normal", then the total food sources for the animals in the reverse food chain were reduced and therefore their number also decreased. If cyclical extinctions are a phenomenon that also occurs on other stars, then the same cyclical processes apply in the opposite food chain.
If you want, you can see the parallel activity of the two food chains as a kind of biological equivalent to the law of conservation of energy. Just as energy does not disappear, but only takes and expands form, so does life. From the time they began to develop on a certain planet until the possibility that they stop for any reason, the whole biological mass and its chemical components does not disappear, it only takes on and expands form during biological evolution starting with the poorest animals and ending with the most developed animals.
Sources
1. Marcuse Hess Adi - Biology Today, Chapters in Biology, Tel Aviv Books 1995, p. 176.
2. Dixon Doel - After Man, Zoology of the Future, Sefrit Maariv, 1984, p. 21.
3. Yablonka Hana - Evolution, Unit 2 The Open University, 1994, p. 120.
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6. Eshat Yoram - "The Greatest Extinction of All" Galileo, November 31, 1998, p. 46.
7. Marcuse Hess Adi - ibid. 176-177.
