Longest animal cryptobiosis
Who
Panagrolaimus kolymaensis
What
46,000 year(s)
Where
Russian Federation ()
When

The longest state of cryptobiosis (suspended animation) known for an animal is 46,000 years. Specimens of Panagrolaimus kolymaensis, a previously unknown species of nematode (roundworm), were collected in this frozen state from Russian permafrost precisely radiocarbon-dated to that age and present near north-east Siberia's Kolyma River. The worms were then successfully revived in the laboratory. The most recent research into these nematodes was published in the journal PLOS Genetics on 27 July 2023.


Animals entering cryptobiosis reduce their metabolism to exceedingly low, barely functioning levels in order to withstand extreme environmental conditions – in this instance, extreme cold (specifically known as cryobiosis).

The discovery of long-frozen, cryptobiotic Russian nematodes was first outlined in a 2018 study that estimated them to be approximately 42,000 years old. That was originally reported in the journal Doklady Biological Sciences in May 2018. However, this new, latest study of July 2023 pushes the time-span of cryptobiosis for nematodes (and thus for all animal forms) back a further 4,000 years.