The olm, a troglobite

To see life on another planet, most would suggest a radio telescope or a NASA explorer vehicle. Yet immediately below the earth’s surface there exists an otherworldly ecosystem populated by creatures that never see the light of day. These animals are the troglobites — crustaceans, amphibians, insects and more — built to survive in the dark, limestone labyrinths that form most of the world’s cave systems.

A pseudoscorpion that doesn’t have a stinging tail and instead injects venom with its claws. A Nelson cave spider with claws on two of its super-long legs that measure just shy of six inches. A whitish, almost transparent cave crayfish that can live over 150 years. These are just some of the troglobites, many of which possess similar evolutionary adaptations: blindness, long limbs and spiky feet to better navigate rocky terrain, and lack of pigmentation as there is no need for camouflage in the dark.

Of all the troglobites, it is perhaps the proteus anguinus, or the olm, that is the star. In Slovenia, a tourism industry exists for those who desire a glimpse of the ghostly salamander that’s beguiled humans for hundreds of years. The first written account of the olm dates back to 1689, in which scholar Janez Vajkard Valvasor disputed the belief that olms were baby dragons. Found in the Dinaric Karst of Europe, it’s easy to see why olms could be fodder for myth. They are blind, yet have barely visible, regressed eyes covered by skin. Their serpentine body can grow over a foot in length, and is covered by whitish, translucent skin that’s artfully highlighted by two frilly pink gills at the back of its head. And, unlike other amphibians that metamorphose into an adult form, the olm retains its larval features, a phenomenon known as neotony. Olms spend their whole lives in water, and so there is no need for them to develop terrestrial characteristics.

In keeping with this fairytale-like appearance, olms are said to be able to live up to 100 years and can go without eating for several. Yes, several years. They, like many troglobites, have exceptionally slow metabolism in large part because of the dearth, or erratic availability, of food. Like other troglobites, the olm compensates for lack of vision by using other, specialized senses. Olms’ ears are capable of receiving sound waves in water and vibrations from the ground, their sense of smell is keener than that of most amphibians, and they possess sensors in their heads called “ampullary organs” that enable them to detect weak electric fields.

Despite such specialized capabilities, troglobites are critically connected to what’s going on above earth’s surface. For a nutritious banquet, some troglobites feast on piles of bat guano found on cave grounds. Tree roots that grow through cracks in a cave’s ceiling and leaves that flow in with water can also provide nutrition. But this water can also bring destruction. Human waste — such as sewer leaks, runoffs, and pesticides — can flow into caves disrupting an ecosystem so sensitive it is said that even human dandruff can upset its balance.

Excavations and the building of roads can also threaten cave life directly. It’s important to note that most of the world’s caves have yet to be fully explored or discovered. The limestone labyrinths beneath us are indeed the earth’s last frontier. It’s a fascinating notion –- some of us may be living above an ecosystem populated by strange species, some millions of years old, and not even know it. In 2007, environmental protection officials in Australia halted a multi-billion dollar iron ore mining proposal when 11 species of troglobite were discovered in the area to be mined. Unfortunately, the ruling was overruled several months later. The battle between moneyed interests and our wildlife continues, unfortunately with greater frequency and scope.

Troglobites are at great risk. This includes the beloved olm which is presently listed by the IUCN as threatened, a circumstance that should be taken very seriously, not only because we should be stewards of our planet (above its surface and below) or because the olm is a fascinating, wonderful species, but also because it is the olm’s very sensitivity to such things as pollution that portends what affects humans as well.

Photo © WNET.ORG/Icon Films

It is the greatest mass extinction since the dinosaurs.  Population by population, species by species, amphibians are vanishing off the face of the Earth. Despite international alarm and a decade and a half of scientists scrambling for answers, the steady hemorrhaging of amphibians continues like a leaky faucet that cannot be fixed or a wound that will not heal.  Large scale die-offs of frogs around the world have prompted scientists to take desperate measures to try to save those frogs they can, even bathing frogs in Clorox solutions and keeping them in Tupperware boxes under carefully controlled conditions to prevent the spread of a deadly fungus. Will it ever be safe to return the frogs back to the ecosystem from which they were taken? Buy the DVD. This film premiered April 5, 2009.

Scientists are struggling to understand why frogs are dying all over the world.  And not just frogs – but also other amphibians, like toads, salamanders, newts, and caecilians.  Herpetologists are scientists who study amphibians and reptiles.  The better they understand what’s going on, the more likely they’ll be able to suggest how to help the frogs.

But everyone can be a part of the solution.  Here are some ways you can help:

Educate Yourself

Learn more about frogs at your local aquarium or zoo.  Natural history museums are also a good place to explore.  In New York City, for example, the American Museum of Natural History has an upcoming exhibit (opening May 2009) all about frogs.

The internet makes it easy to find frog news, ranging from action-oriented to more technical.  Many people have started their own frog-related websites.  Some scientists have frog blogs, like this one by Dr. Roland Knapp, a research biologist at the University of California’s Sierra Nevada Aquatic Research Laboratory.

Knapp studies the mountain yellow-legged frog.  When scientists showed that trout introduced into Sierra Nevada mountain lakes decimated the native frogs, the National Park Service, the U.S. Forest Service, and the California Department of Fish and Game joined together to remove non-native trout.

Just as the frog was recovering from trout overstocking, it was hit with the amphibian chytrid fungus.   The Center for Biological Diversity petitioned to add the yellow-legged frog to the endangered species list to protect them by law, but it remains only a candidate for now.

Keep informed about legislation that affects your local frog populations.  You can help frogs face threats like habitat destruction, global climate change and disease.

Protect the Environment

One of the most important ways to help frogs also helps humans -– taking care of the environment.

Frogs are particularly susceptible to changes in the environment.  Their usually moist skin helps their weak lungs by exchanging oxygen and carbon dioxide with their environment – both in water and out of it.   In fact, last year scientists found a frog without lungs -– it breathes only through its skin.

Over 6,300 different species of amphibians are known – and new species are still being found.  Nearly half of the species are in decline, mostly from threats to their habitat.   Frogs lose their homes to development, but they are also harmed by garbage, non-native plants and animals, and discarded chemicals.

Watch what you throw away—and where you throw it away—to keep frog habitats trash-free.  The water that ends up in storm drains, for example, often travels through forests and grasslands and dumps into wetlands – all prime frog habitat.

On the other hand, shorelines should stay naturally cluttered with the leaf litter, rocks and logs that frogs use for cover.   Frogs evolved over millions of years to fit into specific ecological niches defined by factors like temperature and water levels.   They need clean water to survive,  but they also eat—and feed—other species.

Don’t introduce non-native plants and animals. The tadpoles that hatch from frog eggs depend on finding their favorite plants to eat and hide under.   As with the stocked trout and the mountain yellow-legged frog, sometimes even one out-of-place species can disrupt an entire habitat.

The invasive species can sometimes be another frog – like African clawed frogs and American bullfrogs that were moved outside their original habitats.  The worldwide export of some frogs may even have contributed to spreading the amphibian chytrid fungus around the world.   African clawed frogs were once exported for medical uses and are now popular as pets. Bullfrog legs are exported all over the world as food, especially from Indonesia.

If you’d like to keep a frog as a pet, look for a pet dealer who propagates his or her own animals and don’t release the frog into the wild without consulting an expert to see if it will be an invasive species.

Reduce chemical use. The water table on which we depend collects a lot of the chemicals we flush down our drains or add to our lawns (PDF), despite our best efforts to treat the water.

Chemical pesticides used in industrial agriculture harm frogs.   But declines in frog populations also show us that something is wrong with the water we drink.

Dr. Tyrone Hayes is a developmental endocrinologist at the University of California, Berkeley.  He studies how pesticides both affect amphibian development and also promote reproductive cancer in humans.

The pesticide atrazine, which is found in almost every American’s drinking water, causes hormone disruptions in both frogs and humans.

“[It] doesn’t matter if you’re a frog, a dog, a cat, a hog, or a farmer,” says Hayes.  “The hormones that are disrupted—testosterone, estrogen, thyroid hormones—those are all the same hormones.”

Hayes’ laboratory plays host to several egg-producing male frogs – frogs that were exposed to doses of atrazine a third of what’s allowed in drinking water.  Hayes says the same dosage promotes human cancers.

Don’t flush medicines down the toilet. Pesticides degrade water quality, but so do drugs flushed into our environment (PDF).  The treatment plants that process our wastewater don’t always remove pharmaceutical chemicals.  Most medicines should be thrown in the trash – sometimes mixed with kitty litter or gravel.

Conserve water. The less water you use, the less has to be treated.  And the more water stays with frogs in natural environments.

Support Conservation

Give the frogs some time. If you want to be hands-on, find a local habitat preservation or citizen science monitoring program.  Or you can take part in a 24-hour BioBlitz near you.

Put your money where it counts. Many environmental organizations (such as Amphibian Ark and Partners in Amphibian and Reptile Conservation), zoos and aquariums, scientific consortiums, and countless community groups are already tackling the global frog crisis.  But there’s still a lot to do.  Donate or raise money for your favorite.

Chytrid continues to move quickly, extinguishing entire frog populations in a matter of months.  Scientists have taken drastic measures to counteract it, such as evacuating frogs from the wild and sheltering them in a sterile environment.  The El Valle Amphibian Conservation Center in Central Panama, for example, houses 58 species of frogs in their facility, including the rare golden frog, which no longer exists in the wild. To date, the only chytrid-free area left in Panama is the Burbayar Forest, a thriving environment still full of healthy, unaffected frogs.

Frogs may seem small and insignificant, but their bodies may hold the key to important new discoveries in medical research.  Scientists are finding that chemical compounds found in frogs’ skins can be used to treat pain and block infections, and are even being explored as HIV treatments.  Our chances for the discovery of future medical miracles may be slipping away with the disappearance of these tiny creatures in our midst.

Their impact on the world’s ecosystems is great.  Frogs sit right in the middle of the food chain, and without them, other creatures are disappearing, too.  We are only just beginning to understand what life may be like without them.  The race is on to stem the tide – before the next frog crosses the thin, green line.

Frogs: The Thin Green Line premieres Sunday, April 5 at 8pm ET on PBS (check local listings).

Filmmaker Allison Argo at the American Embassy in London

I’ve just returned from London where there was a special screening of Frogs: The Thin Green Line at the American Embassy.  It was great to see the enthusiasm of the audience — and their concern.  The amphibian crisis is an international one, and folks throughout the world are worried.  Even Prince Charles is taking action. Frogs and princes have had a long association, but Prince Charles is taking it to new heights. Check out his first YouTube movie (you can also see it on his website: www.rainforestSOS.org).

You can catch another special screening of the film if you live in the San Francisco area. It will be shown at the Museum of Natural History on June 18. I’ll be there to talk to the audience and answer questions — and Tyrone Hayes will be there, too. I’m hoping he’ll do his “Frog Rap” after the film. It’s really sensational!

Later this summer there’s also going to be a screening of the film in Houston. No date yet, but stay tuned for more info…

In the meantime, don’t forget our amphibian friends: lay off the pesticides and fertilizers in your gardens and yards — and keep your energy consumption down by reducing your driving and turning off lights and appliances when you don’t need them! I’m also trying to buy organic whenever possible — and I’ve decided to create a frog pond in my back yard this summer. I got inspired after reading about how even a small homemade wetland can help amphibians.

- Allison Argo

Poison dart frog

Almost a year ago NATURE asked me to make a film about the disappearance of amphibians.  I’d made a film on that very subject 15 years ago, so I was a bit reluctant… for about a nanosecond.  Then I realized I couldn’t say no.

The fact is, since making my prior film dozens of frog species have disappeared -– and the decline of amphibians has escalated into one of the greatest environmental crises of our time.  Scientists are calling it the greatest mass extinction since the dinosaurs.  It’s HUGE!!!

The other reason I said yes is: I love frogs.

So, on a blustery day in April I began to piece together my stories… Since the crisis is global, that meant finding characters and frogs in spots as far away as Australia and South America, as well as right here in our own backyards.

The research was sobering.  Amphibians have survived for 360 million years and suddenly they’re vanishing…  I quickly learned that there isn’t any one culprit; frogs are getting hit from just about every direction: climate change, habitat loss, chemical run-off, introduced predators, over-collection, and deadly diseases… Basically, humans have stirred up a perfect storm for amphibians.

Over the next three days I’ll be posting more about my experiences with Frogs… Tomorrow: Panama (where we were faced the challenges of filming frogs in the middle of a wet jungle at night).  Hope you’ll come back…

- Allison Argo

Dr. Karen Lips remembers when she came across the first infected frog at her pristine research valley in the cloud forest of El Cope in Panama.

For eight years, a team of scientists worked with Lips, a conservation biologist at the University of Maryland, to stake out conditions at the site, logging the number of frogs, tadpoles, and eggs for each frog species. They surveyed almost 30,000 amphibians. The team also kept track of where the frogs lived, when they bred, and the types of predators they faced.

“Everything was great until one day we found an infected frog. The next week we found the first dead frog. And within the next 4 months, we found 400 dead frogs,” says Lips. The frogs were infected with an amphibian skin fungus. “Seventy percent of the species that occurred there were found either dead or infected.”

By the next year, all the frogs in the streams had disappeared. Now, above the mountain streams of El Cope, the cloud forest is eerily silent – devoid of once-ubiquitous frog calls, but also of the rustling of snakes and the scrambling of lizards. The streambeds grow slick with algae that blooms unchecked without interference from snacking tadpoles stirring up sediment. The tadpoles also infused the crystal-clear streams with nitrogen – important for plant growth.

“The minute the tadpoles are gone, the water quality changes,” says Lips. “Whatever happens in those headwaters has an impact downstream.”

The fungus epidemic at El Cope documented how the disappearance of frogs triggers a chain reaction in an ecosystem. The storm front of the amphibian fungus is advancing 14 to 62 miles per year on every continent but Asia. It’s probably responsible for the extinction of at least 100 amphibian species since the 1970s. But the biggest menace to frogs remains habitat loss from development, pollution, and global climate change.

With nearly a third of the known 6,300 species under threat, scientists are racing to better understand the role of the frog in our world. Frog science may evoke the smell of formaldehyde and the image of scalpels glinting by pinned and splayed legs, but scientists have been turning to frogs — while they’re still alive — to better understand the health of our ecosystems and our bodies.

The evidence of algae growth spurred by tadpole declines describes only one fractured link in the ecological chain anchored by frogs. Wasps and spiders eat frog eggs; shrimp, fish, and dragonfly nymphs eat tadpoles; birds, snakes, and lizards eat frogs; and frogs in turn eat a wide variety of worms and insects.

“Amphibians play a huge role in these ecosystems in terms of feeding on insects and flies, many of which are disease vectors for lots of human diseases,” says Lips.

By eating pests like mosquitoes and their larvae, frogs may control the spread of diseases like avian malaria and dengue fever.

As a side effect of filling their bellies with bugs, some frogs concentrate chemicals called alkaloids in their skins. The frogs act as vacuum cleaners, sucking up insects or mites that contain the alkaloids. Studying the skins of poison frogs has yielded a catalog of over 800 alkaloids.

Researchers are just beginning to explore the chemical goldmine to be found in the skins of frogs, especially tropical and Australian frogs – the very frogs that are hardest hit by the amphibian chytrid fungus. Chemicals secreted and sequestered by frogs may turn out to be very useful to humans.

In the wild, the one-inch-long poison dart frog secretes enough of an alkaloid called batrachotoxin to kill 100 people. The poison locks open the sodium channel in nerve cells, potentially leading to cardiac arrest. Scientists examine the channel’s mechanism to study drugs like anesthetics and antidepressants.

The lessons locked in alkaloids may be able to be used to create non-addictive painkillers, appetite suppressants, and medicines to fight Alzheimer’s disease. Several pharmaceutical companies — Abbott Labs and Cephalon Chemicals among them — are exploring chemical equivalents to the frog alkaloids.

Another pharmaceutical company, Genaera, examined another type of chemical secreted by frogs – protein-like molecules, or peptides, called magainins that help frogs’ skin heal quickly from wounds. Magainins can be antifungal, antiparasitic, antibiotic, and antiviral.

Researchers at Vanderbilt University Medical Center in Nashville, Tennessee, found magainins in the red-eyed Australian tree frog that may block infection by HIV – the virus that causes AIDS. The peptide punches holes in the virus’s cell membrane to destroy the virus – instead of attacking internal chemicals like most modern medicines.

And that’s just one peptide, from one frog. Another peptide — from the giant Mexican leaf frog — has shown promise as a potential treatment for high blood pressure. Yet another peptide from the same frog prevents blood clotting and could help scientists cure deep vein thrombosis and heart disease.

Frog toxins may hold keys to unlocking mysteries about our own bodies. But as frog populations face unexplained and unprecedented declines, what we can learn from frogs depends on how long they will be around.

“There are a lot of exciting things going on,” says Lips about the explosion of frog research. But she worries about the future for frogs. “At this point, we’re just keeping our fingers crossed and hoping for something to come through, because it’s not looking good.”