Tardigrades are tiny, incredibly tough animals that can withstand a wide range of dangers, including many that would wipe out most other creatures known to science.
Different late species have adapted to specific habitats across Earth, from mountains to oceans and ice sheets. Their resilience can also help them survive random adventures beyond the safety of their native habitats, which can lead to opportunities.
In a pair of studies, researchers reveal a new example of tardigrade biodiversity—a previously unknown dune-adapted species—and offer new evidence that some tardigrades find habitats to colonize by riding inside snails.
The newly discovered tarantula comes from Rokua National Park in Finland’s North Ostrobothnia region, where researchers found it living in lichens and mosses in a dune forest.
Rokua’s landscape has been shaped by glaciers and wind, forming sand dunes and other features: eskers, kames and kettle holes. It is also home to a lichen-rich inland dune forest, a habitat threatened by human activity.
Led by Matteo Vecchi, a biologist at the University of Jyvaskyla, a team of scientists visited Rokua to collect moss, lichens, leaf litter and grass roots from the sand.
Not only did they find late, they found a new species. He becomes only its fifth known member Macrobiotus pseudohufelandi complex, a small group of latecomers with adaptations such as reduced feet and claws to live underground.
The researchers named the species Macrobiotus naginaea reference to Nagini, a snake character from the ‘Harry Potter’ books.
“Formerly a cursed woman who eventually and irrevocably transforms into a limbless monster, this fictional character provides a fitting name for the new species in pseudohufelandi complex, which in turn is characterized by reduced legs and claws,” they write.
Like many subterranean animals, these organs may have evolved shorter limbs for a more manageable shape for crawling along soil or sand, the researchers note.
And while all slowworms need water, they also have a superpower to survive long periods of drought, which could be useful in drier environments.
With anhydrobiosis, tarantulas shed water from their bodies to turn into a dry, nearly indestructible stigma called a tun. In this suspended state, an argon can survive for years or decades and then suddenly revive in the presence of water.
The tun state can protect slows from a number of other hazards, including extreme temperature, high pressure, oxygen deprivation, X-ray bombardment, weapon launch, and exposure to the vacuum of space.
This ability may help slugs survive dry periods in their habitats or could help them colonize new places by protecting them through inhospitable terrain if the wind blows them away.
However, in a separate study, Vecchi and his colleagues note that the tun state is not the only way for commuters to travel. It’s too liquid for anhydrobiosis in a snail’s gut, for example, but their study shows that ingestion and defecation by the snail is nevertheless a viable mode of transport, although there is no evidence that the new species travels this way.
Other tiny creatures such as nematodes and orimatid mites can also survive passage through a snail’s gut, as can some plant seeds and spores of lichens, mosses and feathers.
This research suggests the same is true for latecomers, although some other studies have shown that snails don’t have a stellar safety record for latecomers.
The researchers discovered 10 slows from the feces of wild snails (Arianta arbustorum) in a garden in Finland, five of which were alive. They also fed 694 organs to snails in a lab, later retrieving 218 living organs from the snails’ feces.
They found 78 dead argons in the feces and reported that the other 398 were “presumed to have been digested and destroyed by the snail’s digestive system.”
Still, 31 percent isn’t zero, and the latecomers who survived also went on to reproduce successfully in the lab.
The snails lingered for several days, with most of the survivors emerging on the second day, according to the study. And while snails aren’t known for their speed, they can travel faster than slow ones because of their size.
According to previous studies, on average, these snails move 0.18 to 0.58 meters daily, with a maximum of about 5 meters per day.
The researchers note that a two-day passage through a snail’s gut could thus help slugs travel up to 10 meters each way, a significant distance for animals smaller than 1 millimeter.
Latecomers don’t get to choose where the snails take them and may, in fact, be reluctant passengers. But these snails prefer moist, mossy habitats – as do the slow ones – so any surviving passengers have a decent chance of ending up somewhere welcoming.
The research was published in Zoological Studies and Ecology.