▲ Water bear worm that looks a bit like an alien creature (imaginary picture). Figure/insect creativity

It may be the most widely distributed creature in the solar system known to mankind.

Do you know that there is life on the moon? Life on the moon originated from a mistake made by the earth people. Last April, Genesis, Israel's first spacecraft that landed on the moon, crashed on the surface of the moon due to a miscalculation. The ship carried thousands of water bear worms wrapped in epoxy resin. According to the sponsor of this project, these water bear insects have a good chance of surviving on the moon.

▲ Genesis spacecraft landing on the moon. Arch Mission foundation

There is no water, no food, no air, and there is endless space radiation around. How does life on earth survive?

The stunt of "the strongest on the surface"-hidden life

The reason why water bear worms are considered to be able to survive on the moon is that they have the "strongest surface" stunt-cryptology: in harsh environment, water bear worms will shrink into a small bucket, reduce their water content from 85% to 3%, and maintain their metabolic level at only 0.0 1% of the normal level, just for survival.

▲ In the dark, the water bear worm will curl up into a "small bucket". Figure/Wikipedia

In order to study the latent ability of water bear insects, human beings have created various extreme environments for them to test their "bottom line". In these cruel experiments, the water bear worm was carried down again and again. If it were any other creature, it would have jumped into the street. William miller, a researcher of biological evolution at Baker University, once found a hidden water bear worm under a rock in desert of sinai. "You know, it has never rained a drop in 25 years! They just wait quietly, don't eat or drink for decades, until the water overflows here, and then resurrect like a soaked sponge, as if nothing had happened. "

▲ Aerial photography of Sinai Peninsula desert. Figure/Wikipedia

In addition to coping with drought, aquatic insects can cope with both high and low temperatures. Among the water bear worms, some "real warriors" can tolerate the low temperature just above the absolute temperature of 1 degree Celsius, that is, minus 272 degrees Celsius, while others survive the high temperature of 150 degrees Celsius. Although they can only last for a few minutes in extreme cold and heat, this is already a superpower for life on earth. Aquatic insects can cope with high or low pressure vacuum. Some water bear worms can withstand 6000 times the atmospheric pressure, which is equivalent to nearly 6 times the pressure at the bottom of the deepest Mariana Trench on earth. In an outer space experiment in 2007, a European research team "tied" a group of water bear worms outside the Futian -M3 rocket and flew around the earth for 10 days. When these "space shuttles" returned to Earth, scientists found that 68% of the individuals survived.

▲ Space Shuttle Endeavour carrying out STS-11mission. 20 1 1 In May, Italian scientists carried slow-moving animals and other extreme microorganisms (such as bacteria with high temperature and salt tolerance) on the space shuttle Endeavour, which carried out the STS- 134 mission. Figure/Wikipedia

You know, in space, there are not only tests of vacuum and low pressure, but also deadly radiation. The radiation tolerance of water bear worms is 1000 times stronger than that of human beings: for human beings, radiation of 5 to 10 Gy is fatal, but the dormant water bear worms can tolerate gamma rays of 5000 Gy or heavy ion radiation of 6200 Gy. I really don't know what the water bear worm has experienced, and it has evolved such a strong endurance! The strong adaptability makes the water bear worm spread all over the world, and scientists even think that it will drift with the wind, enter a dormant state in the atmosphere, and then resurrect, reproduce and grow in a new environment.

From the slopes of the Himalayas at an altitude of 6000 meters to the deep seabed of 4000 meters, from the ice beneath the Antarctic continent to the tropical rain forest at the equator, from your backyard to the corner roof, water bear insects are almost everywhere. However, they prefer humid and mild environment to dry, cold or hot, because it is actually an aquatic animal. Ponds, lakes and grasslands are ideal homes.

In addition, thanks to the Israelis, there are water bear worms on the moon. In this way, it should be the most widely distributed creature in the solar system known to mankind, right?

Why is the water bear so awesome?

The operation of the water bear worm is so against the sky that some people are quite critical of their life experiences. A documentary company called VICE even swears that they are a kind of creatures originated from aliens-because they can survive in space. Miller sneered at these rumors: "Although water bear worms have unique ability to survive in space, we have no reason to believe that they evolved this ability for space travel."

▲ Water bear worms in the water. Figure/Wikimedia

In 20 15, a geneticist sequenced a freshwater water bear worm. They found that many genes of the water bear worm came from other organisms, so they put forward the conclusion that the water bear worm gained its ability through "star attraction". This magical conclusion was finally characterized as "Oolong", and it turned out that their samples were polluted ... It turns out that the exogenous gene of this water bear worm only accounts for 1.2% of the total gene amount, that is to say, the ability of the water bear worm evolved by itself.

In fact, the water bear worm is not an animal, but a general term for slow-moving animals, which consists of more than 1000 species. They all have barrel-shaped bodies and four pairs of short legs, and they walk like bears, so they are called water bears.

Water bear insects are very small, the largest species is 1.2 mm in length, and most other species are only 0.3 to 0.5 mm. Their prey includes nematodes, bacteria, algae, mites and even small ones. Their tubular mouths have probes that can be used to pierce the outer wall of prey.

The high tolerance to the environment makes the water bear worm a pioneer on the earth. When the water bear worm settles down, it can be used as food to provide nutrients for later animals. However, water bear worms sometimes have the advantage. Now, under the Antarctic ice, because there is no "higher level" predator, it has become a creature standing at the top of the food chain.

▲ Water bear worm lying on a grain of sand. Figure/Wikipedia

The fossil of the water bear worm can be traced back to the Cretaceous, but because it looks so strange, it was not until the emergence of molecular evolution analysis technology that people determined who its relatives were. Through the study of modern molecular technology, it is considered that the water bear insect belongs to pan-arthropod, and its homology includes velvet worm and arthropod phylum (crustaceans and insects) Scientists have found that when the water bear worm enters a dormant state, it will fill cells with a molecule called trehalose, which can not only replace water, but also "bind" the remaining water so that they will not expand rapidly and destroy cells under the action of high or low temperature.

▲ Water bear worm after artistic rendering. Figure/vision china

By studying the genome of water bear, scientists also discovered the unique secret of water bear's anti-radiation injury inhibitory protein. This protein has been widely expressed since the embryonic stage of water bear, and can be combined with DNA as a "shield" against radiation damage. When scientists genetically modified human cells to express the same protein, the cell damage after irradiation was reduced by 40% compared with the control group. Of course, even the water bear worm with the ability to go against the sky can't resist the sudden change of the environment. In a research achievement just released on June 5438+ 10 this year, the survival rate of dormant water bear worms is only 50% when they are heated to 150 degrees Celsius within one hour. Of course, the survival rate of water bear worms in non-dormant state is even lower. If the heating time is extended to 24 hours, most water bears can tide over the difficulties smoothly.

Why pay attention to water bear worms?

Scientists use various extreme environments to "abuse" water bear insects. What is this for? You know, creating an extreme experimental environment is not very cheap. We study water bear insects, of course, not for fun, not because we have any strange hobbies, but because we want to learn from them.

▲ There is also an international conference on water bears and insects, which is the LOGO of the 12 conference. The water bear worm in LOGO is very cute. Figure/12 international symposium on slow-moving animals

The powerful gene repair ability of water bear worm may lead us to find new gene drugs to conquer cancer and even prolong life. In the short term, we can also use its anti-radiation ability to improve sun protection. The fact that water bear worms can survive in space aroused the enthusiasm of astronomers, who began to re-examine the possibility of life on other planets. Of course, the most important thing is that the water bear worm will not age when it sleeps in extreme environment. Although the life span of most water bear worms is only three or four months and the length is only two years, they can "live" for decades by seclusion and then recover in an environment with water. Is this scene familiar? Yes, isn't this technology used in many science fiction movies?

▲ Space dormancy cabin in science fiction movies. Figure/"Alien"

However, up to now, our research on the concealment ability of water bear insects is still in the primary stage, and we know little about the principle of its recovery from concealment. We will learn more knowledge from these little guys in the future, because among them, there may be the key to your space roaming or immortality!

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Zhang Wenyi Chen Yu