A New Tardigrade Species is Found Hiding in a Parking Lot

James Marshall
March 3, 2018

The tardigrades are the smallest known animal on the planet Earth and they are commonly known as moss piglets or water bears are water-dwelling, eight-legged segmented micro animals. They can survive up to 30 years without food or water, endure the vacuum of space, and live in temperatures of up to 150°C. Forget cockroaches - tardigrades will outlive us all. The newest of these odd creatures was the 168th found within Japan's borders.

Tardigrades are a very well-known group of tiny animals - micrometazoans, in the jargon - famous for being pretty much indestructible. Compared to similar species of tardigrade, M. shonaicus has differences around its mouth, organs and leg shape.

Arakawa routinely samples moss he finds around town, he said, but the portion from his parking lot turned out to be special.

"Tardigrades are very hard to maintain in the lab, often because we do not know what to feed them, so M. shonaicus was a rare case where we can maintain the culture, where I succeeded to feed them algae as food". They can suspend their metabolisms and survive enormous amounts of pressure, and they've also been zapped with X-rays.

They were luckily able to successfully breed the tardigrades in the lab and it was actually their eggs that made it clear that they are a new species. These features might help the egg attach to the surface where it is laid, Arakawa said. Once the researchers had the required numbers, they "used phase contrast light microscopy (PCM) and scanning electron microscopy (SEM)" along with DNA analysis to identify "four molecular markers to characterize the new species and determine where it fit in the phylogenetic tree".

The eggs of the new tardigrade are capped with flexible filaments. Image credits: Stec et al (2018). It is also equipped with tentacles that grow from its eggs.

These elongated strings are similar to those found in two other species described since 2015-M. paulinae from Kenya and M. polypiformis from Ecuador.

Previously, researchers knew of only 167 taridigrade species in Japan. This newest version of a tardigrade is even stranger than the ones known before it - even stranger, indeed.

When it comes to survival, few creatures are as sturdy as the tardigrade. In these extreme environments, the animals will enter a type of hibernation called cryptobiosis, in which they recoil into a compact, dried ball and stay dormant for an indefinite period of time. The microscopic dried tardigrades are blown like specks of dust in the wind, so tardigrades can travel widely in this form. There you'll find the paper "An integrative description of Macrobiotus shonaicus sp. November (Tardigrada: Macrobiotidae) from Japan with notes on its phylogenetic position within the hufelandi group". It isn't not known for sure, but hypothesized that they have a wider distribution around the Shonai area in Japan after which they are named.

This all makes the new species a mismash of several other tardigrade species, not too different but certainly not like any species we've uncovered so far.

Journal reference: Citation: Stec D, Arakawa K, Michalczyk? The addition of Macrobiotus Shonaicus now increases this number to 168.

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