Tardigrades are the most resistant animals On the ground. It is usually difficult to see them, because on average they reach half a millimeter in length. They love a moist environment, live in water, and live among algae on land.
Scientists have found that tardigrades can withstand temperatures close to absolute zero (-273.15 degrees Celsius) and extremely high (150 degrees). They can survive for a hundred years without water. They endure a cosmic void and doses of radiation that kill humans. They even survived when fired into the sand at over 2,500 kilometers per hour!
They are commonly found all over the earth. Polish researchers were fascinated How tardigrades travel long distances. After all, they are small and do not move very efficiently (the Latin name for tardigrades – tardigrades means “slow-moving”) how did they spread around the world?
Many small animals travel surreptitiously – on the backs of large animals. Researchers from Adam Mickiewicz University in Poznan, Milena Roskovska and Zofia Kisicevic, decided to check whether tardigrades can do this.
They put tardigrades in one container Milnesium inceptum alone, and in the second with the snails common in Poland from the May squad snail (Cepaea nemoralis). Both species live naturally in the same environment. In the third, tardigrades and snails were placed on a bed of algae.
Three days later, the researchers verified the fate of tardigrades in containers. It turned out that in the empty containers they were still in their former places, but they were moving in the box with snails.
It is true that some of these little animals died touching snail mucus (so there is something bad for them). However, as the researchers add, Tardigrades often reproduce asexually. It is enough for one to go somewhere to multiply.
On the other hand, tardigrades in the container did not move with algae and snails, which are most similar to the natural environment. The researchers believe that tardigrades hiding among the algae have less chance of sticking to the snail. This does not mean that this does not happen in nature – but that it should be examined outside the laboratory.
Are tardigrades not light enough to be carried by the wind? It is theoretically possible that they also travel on tangles of algae (these are their juvenile forms that grow from spores). In 2018, it was reported that it is transmitted not only by snails, but also by wind and water. In the same year, cases of tardigrade travel on birds were also described.
