It all depends on the conditions that have developed on this or that potentially habitable planet. On planets covered with huge oceans, it can be aquatic creatures that resemble the inhabitants of our deep sea.
In a world with strong gravity and a dense atmosphere, large, strong and, apparently, aggressive (due to harsh living conditions) creatures can live. In ice worlds, probably only bacteria can live. To survive, they can unite in giant networks.
Carbon chauvinism
This term is a consequence of the assumption that alien life, if it exists, should be similar to terrestrial life. In particular, the molecules responsible for vital chemical processes must be built primarily from carbon. It is clear that such a form of life is closest to us, therefore it is extremely difficult for earthlings to imagine a different biochemistry. So let's not change traditions.
"Carbon chauvinism" limits our fantasies about other forms of life, but, of course, does not mean that life like the earth does not exist anywhere else.
Aurelia and the Blue Moon
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This is a joint project of Blue Wave Productions Ltd. and a group of American and British scientists commissioned by the National Geographic Channel. Aurelia and Blue Moon are hypothetical examples of a planet and moon on which extraterrestrial life could arise.
Scientists suggest that we can discover a planet like Aurelia within 10 years. It is highly likely that it will orbit a red dwarf. Indeed, it is these stars that are most common (80% of all stars) at relatively small (within 50 light years) distances from the Earth (to detect planets at more distant distances, too powerful telescopes will be needed, which are not yet possible to design).
Red dwarfs are cool stars, producing less than a tenth of the light from our sun.
So, before us is a red dwarf. A planet similar to the Earth - Aurelia revolves next to him. In order for liquid water to form on its surface - an indispensable attribute of the carbon form of life - it must orbit close enough to its star. However, much closer than our planet. After all, the red dwarf, as we know, is much colder than the Sun. Therefore, under the influence of gravity, such a planet will not rotate around its axis and will always be turned by one side to its star. There will be no change of day and night and seasons.
Previously, it was believed that the planets orbiting red dwarfs could not be habitable, since on the one side of this planet the atmosphere should freeze, and on the other - evaporate.
But using a terrestrial weather model, scientists from the Met Office (UK's National Weather Service) proved that liquid water could exist on a planet that does not revolve around its axis and is near a red dwarf.
There will be no light on the dark side of Aurelia, and the temperature will not rise above zero. Unattractive living conditions. On the bright side, meteorological models predict a permanent giant cyclone. Hurricanes and continuous torrential rains sweep overland. However, between the dark and stormy zones, there is likely to be a belt of warm and stable climate. Here, according to scientists, life is more than possible.
Rivers that form in the storm zone flow here, so there will be a huge number of reservoirs. Who can live here?
If we consider that the estimated age of the hypothetical Aurelia is 5 billion years, then the following life forms may be on it. The main one is the Sting Fan. These bizarre creatures resemble plants, but they are animals that have learned to catch daylight. They are fighting for a place in the sun - a red dwarf. Their planet is motionless, so the fans themselves move, taking the best position. The fans of the Sting reach 10 m in height. Their wings stretch towards the sun to provide energy for sugar production. Their lightly engineered hearts transport nutrients through the body. Don't believe me? Think of similar creatures on Earth - corals, jellyfish, some types of molluscs. They also live at someone else's expense, their captives carry out photosynthesis and produce the necessary food. It's a symbiosis.
According to the world's leading biologists and biomechanics, life on Aurelia will depend on Sting Fan. But there are other forms of life as well. For example, the pig-nosed is the planet's largest predator. The height of the pig is 4.5 m, weight is like that of a buffalo The pig-snout meets all the rules for the structure of the animal's body.
Scientists involved in the project suggested that the "Aurelian" creatures, for sure, obey the laws of biology, similar to those of the earth. Thus, it is logical for an Aurelian to have five senses and their organs: eyes, ears, nose, taste sensors, and skin. All these organs should be located in front of the body, since it is the environment that the animal perceives from the front. It is also natural for such creatures to have a brain and a computing center located as close to the sensors as possible. A long neck will allow the body to remain stationary, while the body part will move, tracking down the victim. The intestines take up a lot of space, but they must be in a stable place - for example, at the feet. Legs must be long in order to quickly overtake prey.
Living beings on Earth chose the same methods of adaptation. There are not so many ways of swimming or movement, for example, and living beings for millions of years have chosen the same ones. According to scientists, the situation is probably the same on other planets. On Aurelia, life is ruled by the same evolution.
The second hypothetical object of research by leading world experts is the Blue Moon. It is a fictional satellite of a planet like Jupiter, almost completely covered in water and having a very dense atmosphere. Such conditions allow scientists to assume the presence of flying whale-sized creatures on the satellite.
The Blue Moon should be comparable in size to Earth, but according to the model, atmospheric pressure on its surface is three times that of Earth. A characteristic feature of the Moon is the absence of polar ice caps. The dense atmosphere and ocean covering the surface reduce temperature fluctuations.
An excess of oxygen in the atmosphere should theoretically lead to an increase in the muscle strength of celestial whales, whose wingspan reaches 10 m. Billions of algae and mosses float in this “air”. Celestial whales feed on them.
Non-carbon life form
Most of the life forms on our planet are made up of carbon, oxygen, phosphorus and sulfur. But in 2010, scientists discovered organisms that don't need oxygen.
Silicon is believed to be the most likely candidate for the role of a structure-forming atom in alternative biochemistry. Their properties with carbon are very similar. But silicon atoms have a larger mass and radius, they are more difficult to form a double or triple covalent bond. This can interfere with the formation of biopolymers (polymers that make up living organisms).
And although the main hypotheses for the existence of non-carbon extraterrestrial life forms are based precisely on silicon - it is likely that such life will have much less variety than carbon life. After all, silicon compounds cannot be as diverse as carbon compounds. But if this is the case, then the silicon life form can be so different from the one we are used to that we hardly have the opportunity to fantasize about what the "silicon" aliens look like.
Olga Fadeeva