JUANA SUMMERS, HOST:
In Australia, there's a little critter known as the marsupial mole. It has lush, golden fur. It is blind. It has flipper-like front feet so it can swim through desert sands. And it is not easy to find. NPR's Nell Greenfieldboyce reports on how scientists recently learned some of its secrets.
NELL GREENFIELDBOYCE, BYLINE: There's moles around the world, but the moles of Australia are special because they're marsupials.
NATHAN CLARK: Their body plan and limbs and stuff look just like the European mole or the star-nosed mole, but they're completely unrelated.
GREENFIELDBOYCE: Nathan Clark is a biologist with the University of Pittsburgh. His lab has been studying how different moles have adapted to living completely underground.
CLARK: That's clearly a very extreme change, to go deep underground. Dark, different foods, different air - everything is so drastic.
GREENFIELDBOYCE: A fully subterranean life does have advantages, like protection from predators and extreme temperatures. So within mammals, this lifestyle has evolved independently at least five times. He was really curious about how this happened in Australia, a continent where the northern and southern marsupial moles have been isolated for millions of years. These little marsupials have pouches like kangaroos, but the mole's pouch is upside down.
CLARK: Its pouch did a 180 at one point. Who knows how that happened?
GREENFIELDBOYCE: Presumably it's so the pouch won't fill with sand as the mole swims forward. These moles are so obscure, a mere sighting makes headlines. Clark says they're difficult to study.
CLARK: It's endangered, so you're not allowed to go looking for it. It's extremely rare anyways. And it's in Australia, in the desert. And how are you going to find this thing? It doesn't have permanent tunnels.
GREENFIELDBOYCE: Still, Clark and some other colleagues recently teamed up with biologists in Australia. They took genetic samples from a single museum specimen, a dead female southern marsupial mole. It turns out the mole's closest relatives are two small, nocturnal marsupials, the bandicoot and the bilby. What's more, genetic evidence suggests that the marsupial moles' population may have suffered an abrupt crash around 70,000 years ago, possibly related to climate change.
SARAH LUCAS: I think that's definitely one of the major findings of this paper.
GREENFIELDBOYCE: Sarah Lucas is currently with the University of Munster in Germany and a member of the research team. It's just published its analysis in the journal Science Advances.
LUCAS: They were listed as extremely endangered because we had no idea about what their population dynamics were happening. And, again, it's really hard to find a living one.
GREENFIELDBOYCE: She says another key finding is how the marsupial mole gradually went blind as vision-related genes degraded. First to go were genes related to the eye's lens, then genes for cone cells that perceive bright light, then genes for rod cells used in dim light. This progression was striking and made the researchers wonder if other mammals that have lost vision follow a similar sequence of events.
LUCAS: We're trying to actually study more on how other mammals lose their eyesight to see how unique or not the marsupial mole is compared to them.
GREENFIELDBOYCE: Like bats, for example - they also come to rely less on vision, even though they live in the darkness of the night air instead of the blackness underground.
Nell Greenfieldboyce, NPR News. Transcript provided by NPR, Copyright NPR.
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