CLOSE
Getty Images
Getty Images

Watch: Inside the Tennessee, Alabama, and Georgia (TAG) Caves

Getty Images
Getty Images

In the southern United States, a tri-state region is home to an incredible density of caves. Known as "TAG" (for Tennessee, Alabama, and Georgia), this is a hidden world explored by secretive cavers, for good reason—the more traffic these caves receive, the faster they're destroyed.

In the short film below entitled Sharing the Secrets, director/cinematographer Drew Perlmutter brings us inside these caves, with perspectives from cavers on why these landscapes are so significant and fragile.

If you're interesting in getting started with caving, check out this FAQ.

nextArticle.image_alt|e
Olivier Testa for the Abanda Expedition
Bat Poop Might Be Turning Gabon’s Cave Crocodiles Orange
Olivier Testa for the Abanda Expedition
Olivier Testa for the Abanda Expedition

In 2010, scientists started exploring the Abanda cave system in Gabon after getting a tip about something strange living there: crocodiles. And not just any crocodiles. Orange crocodiles.

Crocodiles will sometimes use caves as temporary refuges during droughts, but the dwarf crocodiles (Osteolaemus tetraspis) in the Abanda caves seemed to have taken up permanent residence there. When we wrote about the expedition a few years ago, the researchers didn’t know much about the cave crocs. They knew they were there, they knew they were weird, and they knew some of them had turned orange. The scientists, led by biologist Matthew Shirley, have since gone back into the caves to study the animals. Their new paper, published in African Journal of Ecology, overturns some of their early ideas about the Abanda crocodiles, showing that life in the caves has been good to them, and offers a new explanation for their strange colors.

After seeing the crocodiles for themselves, the team began surveying the caves and capturing crocodiles by hand, taking their measurements and determining their sex. To see what the reptiles were eating, they used a method called the hose-Heimlich technique, which is exactly what it sounds like. While one scientist flushed a croc’s stomach with an improvised stomach pump, another grabbed the animal and squeezed its belly, expelling the water and the stomach contents through the animal's mouth. They did the same with a group of crocodiles living aboveground at streams in the forest around the caves.

While the forest crocs barfed up freshwater crabs, shrimp, crayfish, and a variety of insects, the cave crocodiles were eating cave crickets and bats—and little else. The difference in diets, the researchers say, suggests that cave crocodiles don’t hunt or feed aboveground and likely have very little contact with their neighbors. The animals have to come out of the caves to breed and lay their eggs because there aren’t any suitable places to build nests in there, but they apparently don’t spend much time on the surface. They’re not entirely trapped in the caves, as the researchers once thought, but they’re still very isolated.

Even with all that time spent in the caves, the Abanda crocs don’t appear to be changing in response to life underground. Despite some physical and genetic differences between them and the forest crocs, the researchers say that the cave crocodiles “showed no signs of physical adaptation, or repercussion, of living in a hypogean environment”—such as the reduced pigmentation or smaller eyes often found in other cave-dwelling animals. The only notable physical change the team thinks is connected to their lifestyle is the crocs’ orange skin. They initially thought that the color change might have been an adaption to living in darkness or caused by their diet. But they now have a different—and grosser—idea.

With thousands of bats hanging from the cave ceilings, the floor has become covered in a caustic mixture of water and bat waste. “We hypothesize that the orange coloration in large adults is caused by ‘bleaching’ of the skin after what is presumably years of inundation in bat guano,” the researchers say. In some cases, they found, the guano isn’t just bleaching the crocs’ skin and changing its color, but eroding it to the point where the scientists could clearly see the animals’ skulls peeking out through the skin.

Those don't sound like the best living conditions, but the caves offer plenty to make up for it. After taking all the animals’ measurements, the researchers found that the cave crocodiles were in better physical condition than any of the crocs living aboveground. The team thinks this is because the cave crocs’ prey—bats and crickets—is abundant (numbering in the tens of thousands), easy to catch, and available year-round. Furthermore, the caves provide a stable microclimate and protection from the elements. The researchers also found more crocodiles in the caves than they did in the surrounding forest, where the animals are vulnerable to logging and bushmeat hunting, leading them to think that the caves also provide some safety from humans. Living in guano may have its costs, but at the end of the day, it’s not easy being green.

nextArticle.image_alt|e
Drone Captures Stunning Images Inside One of the World's Largest River Caves

Tucked away in the Khammouane province of Laos is a tourist attraction called the Tham Khoun Xe, or Khoun Xe cave. The 4-mile-long river cave is one of the largest in the world, featuring passage walls that are an average of 249 feet wide and 184 feet tall. While its massive and beautiful tunnels are open to the public, the site's remote geographic location makes it hard for most people to access. But you can still get to a small glimpse of the cave, thanks to drone footage from Beijing-based photographer Ryan Deboodt.

In an interview with Smithsonian.com, Deboodt spoke about the experience of kayaking into the cave for two days and flying his DJI Phantom Three drone through the darkness. Tourists are typically allowed to go around 300 meters (984 feet) into Khoun Xe, but the photographer and his crew got to see it all, by invitation from the national park that oversees the site.

"It’s very empty, but then you look up in the distance and see these huge stalagmites," Deboodt said. "It’s a very strange feeling—it’s so empty and yet there’s so much big stuff on the sides."

Still, capturing the experience wasn't easy. While some people might assume that caves like Khoun Xe are pre-lit, the video shows that's not the case at all. In fact, the only light sources are from the outside (like, Deboodt's flashlights) and glowing lights on the kayaks.

Deboodt chose to shoot the video with a drone instead of relying solely on still photography because it "just creates a new perspective for me on the caves and a new challenge," he said. "Cave photography is already really difficult, and filming is another step up. You have to deal with all the movements, and it’s quite a bit harder. I like the challenge involved with it."

But not all of the Deboodt's sightings made it into the footage. For instance, the team witnessed evidence that massive spiders made their home in the cave. "In some parts of cave, you can find their legs," he said. "We saw these things that looked kind of like sticks, but it turned out they were big spider legs … It’s not something that you really care to run into in the dark."

Check out the video above for more on the hidden treasure.

Images via Vimeo

[h/t Smithsonian]

SECTIONS

arrow
LIVE SMARTER
More from mental floss studios