Will Smith’s journey into a little-known cave where tarantulas grow as big as dinner plates
In his new National Geographic series Pole to Pole, the actor ventures deep into the Amazon in search of creatures whose venom may yield new life-saving drugs.
Under the hot sun of the high Andes, a team of scientists, local guides, and a movie star trudges downhill on a dirt path. Their long, slippery walk through the Amazon Rainforest ends at Tayos Cave, a massive underground system. The crew rigs up ropes and descends close to 300 feet, the equivalent of a 20-story building. There, in the pitch black, they will seek out venomous creatures—scorpions, centipedes, and spiders—including an unidentified tarantula the size of a dinner plate.
“It’s one of the most amazing ecosystems that I’ve ever encountered,” says Bryan Fry, a National Geographic Explorer and toxicologist at the University of Queensland in Brisbane, Australia. His expedition to the Tayos Cave appears in an episode of National Geographic’s series Pole to Pole with Will Smith—premiering January 13 on National Geographic and streaming the next day on Disney+ and Hulu—where the two get friendly with deep-dwelling creepy-crawlies.
Their goal is to identify new species and explore venoms to discover molecules that could seed powerful new pharmaceutical drugs. For Fry, this expedition is just one of many in his more than two decades spent studying venoms, venomous creatures, and their evolution.
Treasure hunt
The only way into Tayos cave is through cracks at the Earth’s surface. “Any life in there is basically trapped,” Fry says. Because of the difficulty—and danger—of getting in and out, the remote cave is virtually unknown to researchers outside of Ecuador. “Our expedition is the first one that’s going to be publishing the biodiversity of this cave system,” Fry says.
Venturing deep into the cave, the expedition wades through knee- to mid-thigh deep droppings deposited by South American oilbirds that roost in Tayos Cave. These birds frequently leave the cave to forage for fruit and then return, shedding nutrients through their feces that fuel an ecosystem.
Long ago, cockroaches tumbled into the cave and have since evolved to be some 3 inches long, Fry says. The cave is also home to critters such as spiders, scorpions, and centipedes. Aside from the oilbirds and some bats, there are no other vertebrates. “It’s this arthropod empire, basically, and at the top of this heap are these giant tarantulas,” Fry says.
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(Meet the newest species of tarantula. It’s electric blue.)
Inside the cave, Fry and Smith sweep flashlight beams across the walls and turn over rocks. Fry spots a gigantic brown, furry tarantula and captures it in a jar. Later, he knocks it out with carbon dioxide gas. Working quickly before the creature awakens, Smith and the researchers zap the tarantula’s venom glands with pulses of electricity and gently compress the muscles used to inject its venom. On a fang, large beads of venom form, which the team collects in a plastic tube.
Because this cave is so poorly known to scientists, anything they find here has potential to be a new species. With that in mind, Fry’s team collects the creature in a jar to study its genetics and compare it with known animals. They’ll also analyze the effects of the tarantula’s venom and the compounds it contains—a process that Fry has become deeply familiar with over the years.
Venom seekers
Toxic substances have fascinated Fry since childhood. “My first memory is actually being in the hospital from being torn apart by toxins,” Fry says, recalling an episode at age two of spinal meningitis, in which toxins from the microbial infection can wreak havoc on the body. Fry survived but lost hearing in his right ear as a result. “That got me interested in this idea of toxins, these invisible substances that can completely change your life’s trajectory.”
In his youth, Fry had a fondness for critters that slither, skitter, and crawl. His family moved a lot, and, at each new home, Fry would go out armed with a field guide and a pillowcase to collect anything he could get his hands on: scorpions, snakes, spiders, lizards, frogs, turtles, salamanders, and more.
“I was four or five years old when I grandly announced that I was going to study venomous snakes when I grew up,” Fry says. In the process of turning his childhood dream into a career, Fry has racked up a laundry list of harrowing experiences: hundreds of stitches, 27 snake bites, 25 broken bones, three concussions, and one nearly fatal scorpion sting.
“He is very reckless,” says Tim Lüddecke, a zoologist and biochemist at Fraunhofer Institute for Molecular Biology and Applied Ecology in Giessen, Germany, who was not involved with this expedition. But that’s a common trait in researchers who seek out animals for their toxins, he says. It’s not just for thrills: In venomous creatures, researchers see a source of untapped molecules that could have medical payoffs.
Precious habitats
Venomous animals have evolved the ability to make potent molecules. They help with prey capture, deter would-be predators, and fulfill other biological needs. Past ventures into the world of venoms have yielded powerful drugs, such as the blood pressure medication captopril, a modified version of snake venom that’s been used for more than 50 years. More recently, researchers found a compound in the venom of funnel web spiders that is now being tested in clinical trials as a treatment for heart attacks.
Researchers are unlikely to find new compounds in creatures that have been studied extensively, so they have to look in unusual environments. “If you want to find something novel, you need a novel animal, and you’re not going to get anything more novel than the tarantulas from the Tayos Cave,” Fry says. The animals in these settings have encountered new prey and new enemies, “so they will require novel toxins to deal with the situation,” Lüddecke says. Many of these venomous creatures aren’t harmful to humans, so researchers have often overlooked them in studies of venoms.
(It’s tarantula mating season. This is the best place to watch.)
Like islands, caves can act as laboratories for evolution, says biologist Edgar Neri-Castro of the National Autonomous University of Mexico, who collaborates with Fry but was not part of this expedition. “Because they remain isolated for thousands or even millions of years, the species that live inside can evolve in very unique ways,” he says. Collecting and studying venom unveils how creatures have evolved such a wide variety of venoms, and it can help improve antivenoms and treatments, he says, which can be crucial for rural communities that face the greatest danger of snakebites and scorpion stings.
A future of venoms at risk
After collecting samples in the cave, the team makes a grueling trek back, their packs loaded with venom samples and animals they’ve collected. Fry will later realize that he, Smith, and their companions have discovered at least six new species. “It really underscores how much biodiversity there is, and also how precarious it is,” Fry says.
Venom systems are unique in each species, Lüddecke says, and scientists are racing to study venomous species before they go extinct. “It could be that we actually have lost or will very soon lose a couple of blockbuster drugs against cancer and other diseases before we actually can study them,” he says.
Although physically isolated, Tayos Cave is connected to the outside world by its oilbirds, which spend half of the year in forests in other parts of South America. Habitat loss in those areas would endanger the oilbirds and the cave life they sustain, Fry says. That could have effects for drug design and pharmaceuticals—ones that could have lasting consequences on modern medicine.
“Even if people don’t like venomous animals,” Fry says, “they should want them to stay around.”
