24,000 years on ice weren’t enough to kill - Ars Technica

The humble yet remarkably hardy bdelloid rotifer has now surprised researchers yet again—a recent study unearthed 24,000-year-old Siberian permafrost and found living (or at least revivable) rotifers there.

Rotifers aren’t the only living organisms to emerge from permafrost or ice.

But as key players in the bottom of the food chain, newly re-emerged rotifers indicate that maybe we should think about how species that haven’t been seen for millennia might reintegrate into modern ecosystems.

The Soil Cryology Lab in Pushchino, Russia, has been digging up Siberian permafrost in search of ancient organisms for roughly a decade.

The group estimates the age of the organisms it finds by radiocarbon dating the surrounding soil samples (evidence has shown that there is no vertical movement through layers of permafrost).

For example, last year, the researchers reported a “frozen zoo” of 35 viable protists (nucleus-containing organisms that are neither animal, plant, nor fungus) that they calculated ranged from hundreds to tens of thousands of years old.

In their most recent discovery, the cryology researchers found the living bdelloids after culturing the soil samples for about one month.

Besides using techniques designed to prevent this, the team also addressed this issue by looking at the DNA present in the soil samples, confirming that contamination was highly unlikely.

The team was naturally interested in better understanding the freezing process and gaining insight into just how these rotifers survived for so long.

The researchers did find that the rotifers could survive a relatively slow freezing process (~45 minutes).

At least on a microscopic level, it seems possible that intact micro-ecosystems may thaw together (nematodes, rotifers, protists, viruses, bacteria, etc.).