For all their death-defying abilities, one thing that tardigrades are pretty rubbish at is walking long distances, though new research suggests that the podgy little moss piglets may be able to overcome their locomotive impotence by hitching rides on snails. And while snails themselves might be synonymous with sluggishness, the authors of the study published in Scientific Reports suggest that traveling aboard such a gentle mount may be safer than being whisked away by the wind or larger animals.
Measuring just a fraction of a millimeter, tardigrades struggle to move very far on their pathetically stumpy legs, and therefore rely on help from external factors to relocate. Previous research has indicated that the adorable little water bears are sometimes transported in the guts of snails or birds, before being pooped out further down the line.
To survive such a journey, tardigrades enter into a kind of suspended animation known as a tun state, which they achieve by expelling all the water from their bodies via a process called anhydrobiosis. This allows them to endure even the most extreme ordeals, such as space travel.
Once in a more hospitable environment, the microscopic beanbags then rehydrate and resume their various tardigrade responsibilities and projects. Noting that the critters often share their habitat with snails, researchers decided to test their ability to hitchhike on the mollusks’ backs in a series of lab experiments.
To do so, they enclosed tardigrades within silicone boxes inside petri dishes that also contained grove snails. In some dishes, the tardigrades were allowed to snuggle up inside a pillow of moss, while others contained nothing but water droplets for the tiny creatures to float around in.
The tardigrades were only able to escape their silicone boxes when in the presence of snails, and none managed to break out when the snails were absent. “Therefore, we assume the snails were responsible for tardigrade transportation,” write the researchers.
However, the experiments with moss resulted in far fewer passengers aboard the snail express than those involving nothing but water. According to the researchers, this may be because tardigrades like to bury themselves inside bundles of moss, which may reduce their chances of being picked up by a snail.
While snail-surfing tardigrades have never been observed in the wild, previous research has indicated that the little dudes can sometimes be carried up to 1,000 kilometers (621 miles) on air currents. However, the study authors note that when traveling on the wind, “the environment at the final stop is random and may be hostile for a tardigrade.”
“In contrast, a snail is a vehicle orientated to a particular type of a microhabitat,” they explain, adding that “if a snail will take a tardigrade (or tardigrade egg) for a ride, the passenger will [probably] be dropped off within a suitable environment.”
As convenient as this sounds, snail travel does have one considerable downside: deadly snail mucus.
Because this slimy substance is made mostly of water, tardigrades immediately start to rehydrate when they come into contact with it. However, the mucus dries extremely quickly, and the tardigrades struggle to adapt to such a rapid change, often failing to re-enter a tun state fast enough to survive.
As a result, only 34 percent of tardigrades that got slimed survived their journey, compared with 98 percent of those that avoided contact with snail mucus.
Sometimes it’s safer to just stay at home.
