Very few people seek out slugs while adventuring in the woods. Yet if you are trekking through the misty forests of Mount Kaputar, New South Wales, you might just be lucky enough to see an otherwise unassuming slug boldly sporting a fluorescent pink exterior.
The 20-centimeter-long (8-inch) vivid invertebrates are only found within the 1,000 meter-plus elevation eucalyptus forests that ring the mountain.
Previously believed to be a variety of the red triangle slug (Triboniophorus graeffei), a species common along the NSW coast, a genetic analysis proves they are actually a distinct endemic species. A paper describing the as-of-yet unnamed species will be published soon, according to Michael Murphy, a National Parks and Wildlife Service ranger stationed at the mountain who has collected most of the known information about the slug.
''It's just one of those magical places," Murphy said to the Sydney Morning Herald.
''It's a tiny island of alpine forest, hundreds of kilometers away from anything else like it. The slugs, for example, are buried in the leaf mould during the day, but sometimes at night they come out in their hundreds and feed off the mould and moss on the trees. They are amazing, unreal-looking creatures.''
First formed by a volcanic eruption some 18 million years ago, the mountainous slopes have evolved into a moist and cool forest ecosystem that is quite at odds with the hot, arid lowland environment now surrounding it. Naturalists from the NSW Scientific Committee speculate that the slug’s ancestors arrived at Kaputar during a geological period when the entire eastern coast of Australia was covered in lush rainforest, yet as the inland region dried out over the millennia, the population became isolated.
Now, the florid creatures are limited to a “narrow environmental envelope” around Mount Kaputar. Although exact population figures are unknown, the pink slug is currently listed as endangered due to habitat destruction caused by feral pigs and climate fluctuation.
According to the IUCN Red List, the species may soon vanish entirely, because the slug’s unique ecosystem is acutely susceptible to climate change. Rising temperatures, reduced rainfall, and the resulting increase in forest fires will transform their humid oasis into an inhospitable environment resembling that of the lowlands. As the species shifts its range to higher and higher elevations to compensate, they will eventually top out and perish – a process called mountaintop extinction.
As to why the slugs evolved their shocking color? Scientists like Murphy can only speculate. One possible explanation is that it is an adaptation for disguising themselves among the red-toned eucalyptus leaf litter of the Kaputar forests.
“However, [the slugs] also spend a lot of their time high on tree trunks nowhere near fallen leaves, so it is possible that the color is just a quirk of evolution," Murphy told National Geographic. "I think if you are isolated on a remote mountaintop, you can pretty much be whatever color you like.”
[H/T: National Geographic]
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