Most-tolerant invertebrate discovered in Leningrad region

The micro-animal is named Hypsibius vaskelae to honour a village Vaskelovo in Leningrad region where the species was discovered. The study is published in Zootaxa.

The three unknown freshwater tardigrades were found in 1993 in a lake near the railway station Vaskelovo in Vsevolozhskii district of Leningrad region. The-then aspirantura student Denis Tumanov collected water samples for his thesis. The tardigrade, as the scientists says, did not match any known species in Eurasia. Only 25 years after he discovered the species, the report describing the similar species found in South America was published.

“Today, science knows only two similar species, yet represented only by few samples (two and five, correspondingly): they are found in Argentina and Peru, South America”, — says Denis Tumanov.

They must belong to a rare group of species or even to the relict species that existed in early geological eras. Yet it is just a hypothesis as there is little, if any, evidence.

Denis Tumanov, Candidate of Biology, Department of Invertebrates at SPbU

The Hypsibius vaskelae is rather small, even by the tardigrade’s standards: just 300 microns (0.3 millimeters). Apart the species themselves, the scientist found a “pouch” with three eggs. The female species store their eggs underneath the cuticle, afterwards shed them along with the cuticle when moulting. The scientist described the new species mostly by its morphology: unique mouthparts, cuticle stripes, and sculpture of the body surface.

Tardigrades, also known as water bears, are a type of the invertebrates that are a close relative of arthropods. There are 1,200 known species. They are one of nature’s smallest animals (they are never longer than 1.5 mm), feed by sucking the juices from moss, lichens and algae, yet some of them are predators. They have been discovered almost all over the world: from scorching deserts to snowy mountain peaks, from pools and puddles to abyssal zones of the ocean.

More and more new species of tardigrades are being described, says the scientist. Every discovery contributes to what we have already known about their morphology, spread, and evolution. They belong to the extremophiles that are the animals that can survive in extreme conditions: extreme heat and cold, high pressures, rapid changes in salinity. They are most anhydrobiosis-tolerant organisms: they can survive severe dry and then restore.

They can even survive high doses of radiation: some species can cope with ionizing radiation of 570 thousand X-ray units, which is one thousand beyond the fatal doze for humans (400–500 X-ray units). A group of Japanese scientists has performed DNA sequencing of the tardigrades to unlock the mystery of how they can survive in such extreme environmental conditions. The tardigrades have a protein Dsup that prevents the animal’s DNA from breaking. The protein-coding gene was embedded in the genome of model culture of human cells and increased their radiation tolerance up to 40%.

“There are species that have a ubiquitous distribution, — says the biologist. — For example, the Parhexapodibius pilatoi was described from the moss and soils in semi-deserts in the USA, then was found in the soils of the Alps meadows in Italy, and I discovered it at the bottom of the lakes in Vyborgskii district of Leningrad region”.

There are many myths around these creatures. For example, in anhydrobiosis, they can live up to 100 years. It is just a beautiful story, says Denis Tumanov. We have some evidence that the water bear was found in moss herbarium that was kept in a museum for about 120 years. The author of the publication was an amateur researcher, and his account is rather discredited: he got an impression that the water bear moved its leg. In fact, they can live up to 10, at most 20 years in anhydrobiosis.

“The study of water bears is full of further unpredictable discoverings, — says Denis Tumanov. — We often have students in biology who are discouraged by thinking that it is not possible to discover multicellular organisms as the Russian fauna is so well studied. You don’t have to go to the tropics or other exotic locations – just make one step away”.