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The original title: "how to kill" the strongest creature on the surface "water bear worm? "

Photo Source: some things in FoxHD are not poisonous, but they are lethal.

The water bear bug is probably the most indestructible animal on the planet.

In a harsh environment with no food and no water, it turns itself into a ball, stops metabolism, and has a chance to survive for up to 30 years. Using this method, water bears can also tolerate low temperatures close to absolute zero (- 273 ℃), are also good at enduring hypoxia, and can survive in a vacuum.

In addition, even if exposed to radiation equivalent to 1000 times the lethal dose of humans, the water bear bug is not serious. Other scientists loaded frozen water bugs into bullets and shot at the target at a speed of more than 800 meters per second, but the strong impact still failed to kill the water bears. Many people even suspect that even if huge meteorites fall, leading to the mass extinction of life on Earth, water bears may survive.

So, does the water bear bug really have no fatal weakness? Helping them find their weaknesses has long been the research direction of many scientists who do not believe in evil. Recently, two researchers from Poland found a "dead train" for the water bug.

How the snail became an express water bear worm, officially called tardigrade, which is not a species, but a phylum of thousands of species.

Gathered under this door, basically are micro-organisms, most of the body length between 0.3 mm and 0.5 mm, more than 1 mm is considered huge. They have eight feet, each with 4 toes and 8 toes. They have excellent athletic ability, and sometimes they can walk two body-length distances in a second. However, because the body is too small, the speed can only be measured in centimeters per hour, so I have no choice but to be called a "walking animal".

These small animals, which can only be seen clearly with a microscope, should be very difficult to go to distant places on their own. But the fact is that water bears can be found in almost every corner of the earth, whether it is a mountain of more than 6000 meters or a deep sea of more than 4000 meters. So, they also need some more efficient means of transportation than legs to transport themselves to the rest of the world in order to have today's majestic territory?

Scientists have known before that many small animals, such as nematodes or mites, can attach to larger animals and make long trips-a phenomenon called phoresy, which means "phorein" in Greek. This time, researchers at the University of Mitzkevich in Poznan want to confirm that slow-walking animals, or water bears, have similar behavior.

The water bug the team used for the experiment came from a species called Milnesium inceptum. The vehicle prepared for it is the forest spring onion snail (Cepaea nemoralis). The reason for this choice, scientists say, is that the two species overlap in their natural habitats, and their favorite atmospheric conditions are very similar: in places with high humidity, the surface of snails is also wet. such an environment is conducive to water bears to stay active. Another thing, of course, is that snails are bigger than water bugs and have room to carry such passengers. In this way, there is reason to expect the water bear bug to get on the snail train.

The researchers prepared three kinds of boxes: box A with water bears; box B with water bears and snails; and box C with extra moss collected from the concrete wall. After all, moss is one of the daily preferred dwellings of water bears.

Box An is the control group, with only 10 water bugs placed on silicone; box B adds a snail to box A; box C adds moss to box B (photo source: original paper) scientists have prepared 30 of these three boxes, each containing 10 water bugs. So, a total of 900 water bugs are going to take part in the experiment, and their initial positions are all within the range of a silicone square. The researchers put 90 boxes in the feeding room and waited for three days.

After 72 hours, they need to see how many water bears have moved and how many remain where they are. It was found that in the A box without snails, the water bear worms did not leave the silicone box, while in the B box and C box containing snails, some water bear worms left the silicone box.

On the left is the number of water bears that have moved, and on the right is the number of water bears that have moved and survived (photo source: original paper). So scientists believe that the long-distance movement of water bears depends on the help of snails. Although snails are known for their slow movement, for small walking animals, clinging to snails is a high-speed train.

In addition, the researchers noticed that many of the water bears that moved out of the box had died. The first theory put forward by scientists is that a living water bug can fasten itself firmly to the surface with its feet, making it difficult for snails to carry it away, while dead water bugs are more likely to be separated from the surface. it also creates opportunities for snail transport.

Of course, there is another possibility: there is something in the car that can kill the passengers.

Secret scientists who kill water bears suspect that the mucus in snails may be fatal to some water bears.

So they tested some water bears with snail mucus. If you remember that it was mentioned at the beginning of the article that water bears can turn themselves into a ball and stop metabolism in a harsh environment without water, scientists are testing water bears in this state.

Specifically, scientists let snails crawl through the environment where water bears live, leaving their own mucus; then ask the snails to leave, and wait until 24 hours later to hydrate the "fake dead" water bears to see if they will be "resurrected." It turned out that only 34% of the balls that touched the snail's mucus survived, and the rest died. In contrast, 98% of the water bears in the control group that had not been drenched with snail mucus successfully recovered after hydration.

The death rate of water bear worms exposed to snail mucus is relatively high. The main component of snail mucus is water. Scientists suspect that the reason is that the mucus dries too fast: when a snail passes a "fake dead" water bug, it is rehydrating it, but if the mucus dries quickly, it will not have time to respond effectively to the rehydration process and re-dehydration. At this time, it is difficult for the water bear to ball again in the correct posture, which can be explained by the high mortality rate.

However, studies have only confirmed that this method can kill "fake death" water bears, and not a hundred hits. Even snail mucus can kill some active water bears, and as long as one lucky one survives, it will have a chance to take the snail train to the next place and open up a new territory for the water bear family.

If you react slowly, your life may be in danger.

Original paper:

Https://www.nature.com/articles/s41598-022-08265-2

Reference link:

Https://www.newscientist.com/article/2316379-tardigrades-can-hitch-hike-on-snails-to-travel-longer-distances/

This article comes from the official account of Wechat: global Science (ID:huanqiukexue), written by: chestnut, revision: Erqi

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