Oh, rats!

Just what the world needs, a giant rat.

Actually, that might be exactly what the world needs. At a time when the more usual story of species is their extinction, the discovery of a new -- if less than endearing -- species provides a heartening reminder that the Earth hasn’t run out of mysteries and marvels quite yet.

A team of biologists working on a BBC television special found the rat in the crater of Mt. Bosavi, an extinct volcano on Papua New Guinea, one of more than 30 new species discovered in an isolated little world of their own. Though most of the species were bugs, there were also a fanged frog and a fish that grunts. The big find was the silvery-pelted rodent measuring a yard long, including its tail, and weighing in at more than 3 pounds.

It’s a cousin of our common Norwegian rat, which doesn’t actually come from Norway, but this one is as large as a cat and imposing enough to send Fluffy scooting to his litter box. We are happy to report that it’s a vegetarian. Also, having never encountered people before, the rats weren’t afraid of their human visitors. Maybe they should be.

Now that we know about the Bosavi woolly rat’s existence, we need to know enough to leave it alone. The crater of Mt. Bosavi isn’t easily reached, which is why hunters haven’t bothered checking it out. But 20 miles away, trees are being cut down for their lumber; changes to the environment are clearly underway. And it’s all too easy to envision eco-tourists dropping by.

The biologists believe there are other pockets of the world that sustain as-yet-unknown species. They’re planning a new trip with that in mind. With the destruction of rain forests -- which hold the widest variety of wildlife -- it’s a guess whether we will manage to discover new species before we manage to eradicate them.

The Bosavi woolly rat is unlikely to gain the iconic status of a panda or an African elephant, animals endangered largely by loss of habitat, but as we struggle to keep from losing species, this discovery rekindles hope that the story of our epoch is not just of disappearance. Once in a while, we find a new rat.