Meet the tiny Patagonian monito that is a ‘living fossil’ from the ancient past

By Katie Hunt, CNN

The monito del monte, an endearing mouselike creature that lives in the forests of Patagonia, races vertically up trees, covering a meter of bark per second, to feast on insects and summer fruits ripening high in the canopy.

But it’s the monito’s ability to slow down its bodily functions to survive the region’s harsh winters that has fascinated scientists, such as biologist Roberto Nespolo, a professor who studies animal metabolism at the Austral University of Chile.

Once the weather turns cold, the bug-eyed monito builds a mossy nest in a tree hollow. Cozying up with four to eight fellow monitos, it settles in for the winter. There, the tiny marsupial enters what Nespolo described as a deathlike torpor, and its heart rate drops from 200 beats per minute down to 2 or 3 beats per minute. In this inactive state, it conserves energy, only taking a breath every three minutes. Its blood stops circulating.

“I got interested (in the monito) because of the amazing capacity of this marsupial to reduce (its) metabolism and save about 95% of energy during torpor,” said Nespolo via email. His work is featured in the new CNN Original Series “Patagonia: Life on the Edge of the World.”

“That’s what we measured … in the laboratory. Now we could replicate those measurement(s) in the wild, and found that this capacity is even greater. Monitos could hibernate at zero degrees (Celsius), without any harm to their tissues!”

Nespolo has made it his life’s work to understand how these diminutive creatures of South America’s southwestern tip pull off this feat, something that could help us better understand human metabolism and perhaps even help us come up with solutions for long-haul space travel. Space agencies say that if humans want to make it to Mars, figuring out how to induce hibernation in astronauts could be the best way to save mission costs, reduce the size of spacecraft and keep crew healthy.

“Natural hibernators have a number of physiological adaptations that permit them to almost stop metabolism, without injuries, and to wake up weeks later perfectly,” he said.

“So many colleagues are seeking to identify those mechanisms to be applied either for potential human hibernation, or also for medical applications such as organ preservation.”

The monito is a zoological curiosity in more ways than one.

Like kangaroos and koalas, it’s a marsupial that raises its young in pouches. However, the monito is more closely related to its Australian brethren than other marsupials, such as opossums, that live in the Americas — something that’s long puzzled scientists.

Scientists consider the two species of monito (Dromiciops gliroides and D. bozinovici) to essentially be living fossils — part of a lineage called Microbiotheria that’s ancestral to Australian and American marsupials, making them the sole living representative of an animal group long thought extinct.

As a “relict species,” the monito acts as a window into the past that can help scientists understand how they have survived for so long, Nespolo’s research has suggested.

The temperate forest habitat where the monito lives is shrinking, but Nespolo is confident that the tiny creature, whose direct ancestors once roamed Earth’s ancient supercontinent Gondwanaland, will continue to thrive.

“I’m hopeful for the monito because they’re very resilient. They are able to adapt to change as long as their habitat still exists,” Nespolo said in the CNN Original Series.

The-CNN-Wire
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