The deadliest pathogen in earth’s history is wiping out amphibians faster than scientists can discover them. It also forces us to reprioritize how we view conservation.

The Panamanian golden frog, which is actually a toad, breeds near moving bodies of water like waterfalls. Males, however, lack the ability to make sounds so they must get creative, waving their arms and bobbing their heads at prospective females. Th…

The Panamanian golden frog, which is actually a toad, breeds near moving bodies of water like waterfalls. Males, however, lack the ability to make sounds so they must get creative, waving their arms and bobbing their heads at prospective females. These toxic toads, whose skin contains enough poison to kill 1,200 mice, has reportedly gone extinct in the wild due to the spread of a fungal disease through Panama’s rainforests.

With the entire world reeling as a potential coronavirus outbreak looms, we have become incredibly aware of the potential devastation that lies in the wake of destructive pathogens. This heightened vigilance is not misplaced. Some pandemics of the past, like the Spanish flu or the notorious Bubonic Plague, have ravaged populations, killing millions. However, most people are unaware of the deadly pathogens that ravage the animal world until they spill over into our world, like the swine flu. But these diseases have been the scourge of wildlife conservation for decades, spreading through the natural world like wildfire, wiping out innumerable species.

The deadliest of the bunch is Batrachochytrium dendrobatidis (Bd), a disease that has been disastrous for amphibians world-wide. Some researchers have even labelled the disease as the most destructive pathogen in the history of earth. According to the International Union of Conservation of Nature’s (IUCN) Red List, the world’s preeminent database of threatened species, amphibians are the most threatened class of organisms on earth. 41% of the world’s frogs, salamanders, toads and worm-like caecilians are facing extinction. More than 90 species have already succumbed to extinction, and scientists stress that these are only conservative estimates. There is no way to account for all of the potential species out there not yet known to science. Many of these species will be eliminated from the tree of life before scientists even know where to put them.

Amphibian extinction: a global crisis: Click on the photos above to find out what is threatening these endangered amphibians from Asia and Australia to Central and South America.

Similar to coronavirus, Bd, more commonly referred to as chytrid fungus, mysteriously emerged in Asia, escaping the continent in the 1930s before spreading its destructive tentacles throughout the rest of the world. It has been devastating in Australia. It has been destructive in Africa. And it has become a full blown catastrophe in Central and South America. But the reason why this pandemic never made it onto the front pages of newspapers, or prompted large-scale travel restrictions and quarantines, is because this disease did not target people or any creature remotely like us. This decades-long catastrophe demonstrates a cruel reality — wildlife conservation is often a tragic game of triage that favors the cute and cuddly, the charismatic and the familiar, at the expense of creatures like amphibians.

 


 

Amphibian Epidemic

Toughie, the last of his species (known as an endling), died at the Atlanta Botanical Garden in 2016, taking a species barely known to science with him.

Toughie, the last of his species (known as an endling), died at the Atlanta Botanical Garden in 2016, taking a species barely known to science with him.

A tragic example of the demise of the world’s amphibians is the Rabbs’ fringe-limbed tree frog, which quietly went about its life high in the trees of Panama’s rainforests for millennia before scientists discovered it in 2005. Unfortunately, they did not beat the chytrid fungus to these once pristine rainforests that once acted like bastions for amphibian diversity. Rabbs’ fringe-limbed tree frogs reportedly disappeared from Panama by 2007. The last known member of the species, Toughie, a brown frog with wide, dark eyes, died in captivity in 2016. With him, a whole species slipped into extinction. Some 500 amphibian populations have declined due to chytrid fungus, and several species are in critical danger of sharing the same fate as Toughie and his kin thanks to the pathogen’s destructive capabilities.

Bd feeds on the proteins in the permeable skins of amphibians. Amphibians, many of whom live in both water and on land, need their skin to breathe. Often times, the Bd-damaged skin leads to organ failure and death. The disease, along with complicating factors like climate change and habitat loss, has caused an amphibian epidemic as it has spread around the world. The disease originated in Eastern Asia, where it co-existed with amphibians for millions of years before the most destructive strains emerged between 120 and 50 years ago. Unfortunately for frogs worldwide, this coincided with the advent of the global amphibian trade. Many frogs and salamanders were transported out of Asia as pets and food, carrying with them a deadly pathogen in their skin as humans unknowingly sparked extinction. Most of the amphibian casualties occurred after the disease took the world by storm in the 1980s, but it has continued to rage on in the decades since.

Climate change is also exacerbating the spread of Bd and other chytrid diseases. In Australia, an exceptionally extended El Nino season in 2015 led the alpine tree frog population (which included individuals already infected) to rapidly breed and disperse around the area due to the warm and wet climate. Because chytrid fungus does not kill its victims quickly, it efficiently spreads to more victims, which completely wiped out the unusually large alpine tree frog population. Bd is also capable of infecting, to varying degrees, almost 700 species of amphibians, by simply jumping from one to another.

Species that are not affected by Bd, like this American bullfrog in Michigan, can often spell doom for nearby amphibian species as they act like reservoirs for the disease, potentially transmitting it throughout their environment.

Species that are not affected by Bd, like this American bullfrog in Michigan, can often spell doom for nearby amphibian species as they act like reservoirs for the disease, potentially transmitting it throughout their environment.

Sadly, the disease has also wiped out more than just amphibians. A recent study of tropical snakes in Panama found that the overall snake population, in regions where their amphibian prey had been decimated by Bd, was less diverse with fewer healthy individuals. According to the researchers, a similar trend is happening with amphibian predators elsewhere. This is one of the first studies to take into account how destructive pathogens, like Bd, wreak havoc on entire ecosystems by toppling intricate food webs.

 


 

Playing Favorites

Why do we protect certain species at the expense of others? Why is the panda the symbol of wildlife conservation instead of the more endangered Lord Howe Island stick insect, so large it goes by the moniker “tree lobster”? Why are everyday people much more aware of the demise of polar bears than amphibians?

The obvious answer is that pandas, polar bears, tigers and rhinos are either cute or charismatic. In a world with limited conservation resources, these animals are often given top priority from organizations like the World Wildlife Fund (WWF) at the expense of more endangered species. Pandas, which have been downgraded from endangered to threatened, inspire more people than the Rabbs’ tree frog ever could.

Our preference for charismatic mammals has even been proven. One study took place at a zoo in Paris and looked at 10,000 visitors’ willingness to pay for a certain specie’s conservation. Unsurprisingly, the animals that people came to the zoo to see, like lions and giraffes, received the bulk of the theoretical aid, while species like the tomato frog, a stocky, bright-red amphibian from Madagascar, was at the opposite end of the spectrum. The study chalked this up to the similar principle theory that proposes that humans more easily empathize with endangered mammals, especially apes, because they are more similar and familiar to us. Humans and amphibians, on the other hand, are separated by hundreds of millions of years of evolution.

Although many people recoil from “slimy” amphibians, frogs like this Australian green tree frog, are seen by others as adorable. Unfortunately, although this species is currently listed as least concern, it has been suffering from habitat loss and t…

Although many people recoil from “slimy” amphibians, frogs like this Australian green tree frog, are seen by others as adorable. Unfortunately, although this species is currently listed as least concern, it has been suffering from habitat loss and the chytrid fungus which are threats for all amphibians on the relatively amphibian-poor continent of Australia.

Amphibians are also facing an additional roadblock to wide-scale conservation help. By reading about their plight, outlined in harrowing details in articles like this, many everyday people (as well as several scientists) can easily fall into the trap of believing that any conservation effort would be “too little, too late”. While an incredible amount of damage has already been done, and at least 90 species have been wiped out, there are still hundreds of species fighting Bd, climate change and habitat loss. Some species, like the Panamanian golden frog, have been extinct in the wild for over a decade but still cling to survival in captive breeding programs. These breeding programs, in addition to strictly regulating the international amphibian trade and preserving as much amphibian habitat as possible, give these victims of the “most destructive pathogen” ever a fighting chance.

 


 

An Amazing Amphibian Ark

Although we are separated from amphibians by evolutionary history, they are still our ancestors. Shortly after the first fish hauled themselves onto land almost 400 million years ago, they evolved into amphibians, leading to reptiles and eventually mammals. Several endangered species, like the giant salamanders of China and Japan, still resemble primitive amphibians. Although not threatened by Bd, these behemoths (the Chinese giant salamander, the largest of all amphibians, reaches a length of almost 6 feet!) are threatened by polluted water and over harvesting for consumption. When we look at frogs, salamanders and legless caecilians, similarly to when we look at chimpanzees and gorillas, we are looking into the eyes of our distant past. That is definitely worth protecting.

The hellbender, sometimes referred to as a “snot otter”, “devil dog” or an “Allegheny alligator”, is North America’s largest salamander, reaching two-feet long. Found from New York down to Alabama, their wrinkly skin gives them a larger surface area…

The hellbender, sometimes referred to as a “snot otter”, “devil dog” or an “Allegheny alligator”, is North America’s largest salamander, reaching two-feet long. Found from New York down to Alabama, their wrinkly skin gives them a larger surface area to extract oxygen from the water, which has become dangerous in the wild as their natural stream environments have become degraded. Another threat is a strange skin disease that has caused them to lose their feet in the wild. Photo taken at Chicago’s Shedd Aquarium.

Usually bright green on their back, turning over glass frogs reveals an alarming surprise: a clear view of their internal organs, and sometimes their eggs! Found throughout Central and South America, these tiny frogs will protect their eggs, even ki…

Usually bright green on their back, turning over glass frogs reveals an alarming surprise: a clear view of their internal organs, and sometimes their eggs! Found throughout Central and South America, these tiny frogs will protect their eggs, even kicking away predators like wasps.

Amphibians are incredible in their own right as well. Although giant salamanders can reach the size of an adult human, a frog in Papua New Guinea can fit comfortably on a dime with room to spare. The endangered axolotl (“water dog” in Aztec) salamander of Mexico spends its adult life in its juvenile state of development, retaining its pink gills even after its grown lungs. They can not only regenerate limbs with ease, but can regrow their spines, jaws and parts of their brains. The golden poison dart frog of Colombia is rightfully considered one of the most toxic animals on earth. A paper-clip-sized individual has enough poison to kill 10 full-grown men! The skin of glass frogs, from Central America, is so translucent you can see its eternal organs, including a beating heart.

One of the most incredible traits of amphibians is their ability to alert us that something is not right in an ecosystem. Because they breathe through their skin, they are incredibly sensitive to changes in water quality, making it apparent when a toxic chemical drains into a river or a disease ravages a jungle stream. They have been warning us that something has been wrong in ecosystems around the world for decades, but we just haven’t been listening closely enough. We have to ask ourselves – Would that have been the case if pandas and lions were transmitting that message?

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All art and photographs by Jack Tamisiea

Sources:

https://www.mentalfloss.com/article/63130/11-awesome-axolotl-facts

https://www.nationalgeographic.com/animals/amphibians/g/golden-poison-frog/

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