Indeed, they can live in the cold regions of the earth's poles, in mountainous areas with thin atmosphere and common snow, in the dark seabed without light and food, and even in hot and alkaline volcanic hot springs.
As long as you can think of the earth's environment, there are their figures. They are indeed the strongest life forms. What we are looking for on Mars now is this simple ancient microorganism.
Moreover, life has appeared on the earth for more than three billion years, and the simplest microorganisms have always existed. Today, they are also veritable masters of the earth.
But what you never expect is that the vitality of macro life can be surprisingly tenacious, and it is also a fish living in water.
We know that fish will die in a few minutes without water, and their lives are very fragile, but the lungfish living in Africa can definitely refresh your cognition. They have been on the earth for 400 million years and are very old creatures, which biologists call "living fossils".
The existing lungfish are freshwater fishes, which are divided into three families, namely Australopithecidae, South American lungfish and African lungfish. Among these three families, there are 3 genera and 6 species.
There is only one genus and one species of Australopithecidae, which is called Australopithecus. Their appearance is similar to that of ordinary eels, and they have four paddlelike fins. They only have the respiratory system of ordinary fish, that is, they breathe through gills and cannot leave the water.
South American lungfish and African lungfish have filiform pectoral fins and ventral fins, and they have two sets of respiratory systems: fish gills and swim bladder. In the juvenile stage, they mainly rely on gills to breathe underwater, and in adulthood, they gradually lose the function of gills and mainly rely on swim bladder to breathe.
Their swim bladder is a highly evolved respiratory system, similar to the lungs of amphibians, which can breathe directly in the air to get the oxygen they need, so African lungfish look like fish, but if you keep them trapped in water for a long time, they will drown.
Because they need to surface to breathe air every once in a while, biologists believe that this kind of fish had this ability 400 million years ago and has never changed until now, so lungfish has become a "living fossil" on the road of biological evolution on earth.
We know that all creatures on land, including amphibians, reptiles and mammals, were the first fish to migrate to land hundreds of millions of years ago.
Biologists found a complete fish with a quadruped skeleton in fossils. It lived about 380 million years ago. Biologists have seen the earliest skeleton structure of quadrupeds from fossils. These structures are all wrapped in fins, and we can find the skeleton prototypes of existing land creatures, including humans.
Therefore, we believe that this fish had the ability to crawl on land 380 million years ago. They may be the earliest creatures that walked on land and the ancestors of terrestrial animals.
But if they want to climb the land, they must be able to breathe in the air, and 400 million years ago, lungfish explained that the ability of fish to breathe in the air was earlier than that of quadrupeds.
So the existing lungfish is an evolutionary living fossil, which explains some evolutionary mysteries for us.
But lungfish can not only breathe in the air, they also have the ability to "fake death" to stop time.
Although lungfish can breathe in the air, they never go ashore. Like other fish, they like to live in water. They often eat small fish and crustaceans at the bottom of streams, ponds and swamps, as well as roots and seeds of plants.
The freshwater environment where lungfish often live often dries up, which is a fatal blow to all aquatic animals, but it has no effect on lungfish.
Because they have evolved a very cow coping strategy to adapt to this environment, when drought comes, lungfish will dig holes at the bottom of the river bed, bury themselves in a cave 20 cm deep, and put their heads and tails together, and their bodies will secrete mucus to form mud cocoons;
In order to prevent the body from losing water too quickly, only a small hole will be left at the top of the hole to breathe. At this time, lungfish will minimize their metabolism in the body. They don't eat, drink or excrete for a long time, and they are in a state of "suspended animation" to cope with drought.
During this period, the energy it consumes is the fat accumulated in the body. Once the water comes in, the surrounding soil becomes soft, and the lungfish will wake up and climb out of the cave.
Generally speaking, the longest drought in Africa lasts only six months, and lungfish can cope easily in dry soil. It is even reported that if they don't wait for the rain, they will never wake up, and they can stay in a state of "suspended animation" for four years.
Therefore, lungfish are very resistant to natural disasters, and general disasters are like tickling them. After all, creatures that lived 400 million years ago have proved everything up to now.
Because from 500 million years ago to today, life on earth has experienced five mass extinctions. According to the time when lungfish appeared, it experienced at least four times, and each catastrophe caused more than 75% species extinction on earth.
Lungfish have survived to this day. Although their species number has decreased a lot compared with Devonian, they are still very prosperous and not endangered.
The only threat to them is that Africans sometimes dig them out of dry soil to eat, but the smell of this fish is too strong for everyone to accept, so humans will not pose a great threat to them.
Biologists are most interested in how lungfish enter and stay in suspended animation, which is very important for human beings. If humans have this ability, or have some kind of machine, they can also enter the dormant state of suspended animation.
This is of great help to our future space travel and medicine. We often see in science fiction films that human beings need to sleep when traveling in space by spaceship to fight for a long time, but human beings do not have such technology at present, and space dormancy is still in science fiction.
If humans can sleep, they can also travel in the future, which is safer and more reliable than the current cryopreservation.