Wildlife

30-Year Deep Freeze

After being locked in a deep freeze for more than 30 years, two microscopic creatures called tardigrades have been resuscitated, with one of the adults getting busy with reproduction "immediately" and "repeatedly," scientists reported.

Scientists were even able to revive a tardigrade egg after it spent the past three decades cooling its jets alongside the mature duo in a researcher's freezer.

Their findings shattered the previous preservation and revival record for tardigrades and their eggs, which had been eight years for frozen tardigrades and nine years for dried eggs stored at room temperature.

Scientists retrieved the two microscopic Acutuncus antarcticus hitchhikers and one egg from a piece of frozen moss that had been collected in Antarctica in 1983. For years, the moss was kept frozen at minus 4 degrees Fahrenheit (minus 20 degrees Celsius.) During that time, the tardigrades maintained a state known as "cryptobiosis," showing no visible signs of life and with their metabolic processes at a standstill.

But after more than 30 years in this suspended state, they were brought back to life. Scientists rehydrated them and video-recorded the results, observing that after just one day, a revived tardigrade was tentatively stretching a pair of its stubby legs. Six days after rehydration, the tardigrade was moving its body, as though it were trying to lift itself, the researchers noted. After 13 days had passed, the animal was eating algae, its first meal in decades, And after 22 days, eggs were visible inside the tardigrade's chubby body.

It eventually laid 19 eggs. A. antarcticus reproduce through parthenogenesis, which means that their embryos grow and develop without fertilization, and in this instance, a total of 14 hatchlings emerged.

The other tardigrade survived for just 20 days after rehydration, and died without reproducing. But the frozen egg hatched and produced a larva that went on to lay 15 eggs, of which seven hatched successfully.