In 2006, in the central rainforest of Panama, David Attenborough and the BBC documentary team filmed the golden-yellow Zetsch toad there. That was the last time a human imaging device had recorded the animal in the wild.
Zetsch toad | Yinan Chen / Wikimedia Commons
A golden toad that speaks "sign language"
For people, the rainforest is probably quiet. The leaves swayed by the wind and the occasional noisy perch bring only a relatively soft white noise. But if you lean down and look low enough, you'll be back in a small "rainforest" that envelops you in a deafening sound. Zetsch toad lives in such an environment: the male enclosure is king, and a fallen wood or a stone covered with lichens next to the noisy stream is its sacred kingdom - attracting females and breeding, Zephyllum toads are almost lifelong in this vicinity.
Zetsch toad's habitat is | Brian Gratwicke / Flickr
Like most frogs/toads, Zephyllus can communicate with each other through sound. The lack of eardrums did not cause them to lose their hearing, and although the cries of small bodies were easily masked by the noise of the environment, they still had the ability to distinguish between similar sounds and orientations. The regular cries of the males were a means of mutual temptation, and any uninvited guest who stepped into the territory would receive a verbal warning from the lord.
Zetsky's "sign language" | BBC Studios / Youtube
In addition, they have evolved a unique "sign language" – gently swinging their forelimbs, friend or foe, at a glance. For females, the male's "sign language" represents friendship and overture; between males, "sign language" is a demonstration signal in addition to verbal warnings, and fruitless communication is short contact.
After the fight, the losing side chooses to give in | BBC Studios / Youtube
The golden body color makes the Zee's spotted toad particularly prominent in the rainforest. Encountering such an animal in the wild can easily lead to the fact that it carries toxins. The toxin of the Zephyllum is deadly to humans, and the local natives used it to make poisoned arrows. Some snakes can digest these toxins, so Zephyllum's means of resisting enemies are not foolproof, but fortunately there are not many such natural enemies.
The Zetsky spotted toad in the middle of the hug | Brian Gratwicke / Wikimedia Commons
Deadly infectious diseases
The rainforests of Central America sheltered zebra toads and many other amphibians until a fungus broke the calm. Batrachochytrium dendrobatidis swept through the rainforests of Central and South America.
This is a water-borne pathogen that produces zoospores with flagella through asexual reproduction. Using flagella, zoospores move freely in the water, and after contacting the skin of frogs/toads, they can enter the subcutaneous skin of the host, form cysts under the epidermis, and then develop into zoosporangia; zoosporangia can produce and release more zoospores into water bodies. These new zoospores can repeatedly infect the same host, or look for the next victim.
The life history of Chytrid frog fungus | Collins/PNAS (2016) (Chinese: Species Calendar)
For frogs/toads, the skin is an extremely important organ, not only as a first barrier against various pathogenic factors, but also as a function of breathing, regulating body temperature and penetration. If the skin is invaded by the frog chytrid fungus, the water and salt metabolism will be unbalanced, and eventually the heart will die.
With the exception of Antarctica, chytridiosis is currently found on every continent, covering at least 56 different countries and territories; of the more than 1,000 species that have been tested, 42% are infected. Retrospective studies have also found that before the frog was officially named, it had spread in Mesoamerica – although it had not been discovered early.
The spread of Chytridiosis in Central America marks the year and the distance at which each stage is advanced on average per year (left); transmission in South America is even earlier and more directional (right) | Lips et al. / PLOS Biology (2008)
An analysis of a total of 234 isolates around the world shows that the Korean Peninsula is a hotspot for the genetic diversity of Chytrid frogs; East Asia is likely to be its birthplace.
So, how did Chytrid frog spread around the world?
In the 1930s, scientists discovered that female Xenopus who were injected with pregnant women's urine (containing the human chorionic gonadotropin hCG) lay eggs the next day, so they were used as a pregnancy test tool. At the same time, Xenopus is also an excellent laboratory animal, and the trade against them has spread around the world, and the frog chytrid fungus lurking in the skin of Xenopus laevis has spread all over the world. People once thought that Xenopus laevis was the "culprit" who invisibly spread Chytrid disease.
The pot-backed Xenopus laureate | Tim Vickers / Wikimedia Commons
Now we know that Chytridium did not originate in Africa, and that Xenopus laevis is not a "mastermind". However, international trade is still difficult to get rid of. In fact, it is the increasingly developed international biological trade and commercial exchanges that inadvertently promote the global spread of chytridiosis.
Although Panama is small, it is a land bridge connecting North and South America, and the Panama Canal is an important waterway connecting the Pacific Ocean and the Atlantic Ocean. This world-renowned shipping route has been in operation for more than 100 years and is still an important part of world trade. The social contribution brought about by the prosperity of shipping is indelible, but unfortunately, people have not realized for a long time that the whistle of ships on the docks may also be the death knell for Zee's spotted toad.
As the black arrow indicates, a few tens of kilometers from the Zephyllum habitat (red zone) is the Panama Canal | IUCN
Currently, regardless of the continent, wild amphibians naturally lack the ability to fight Chytrid frogs. If left unchecked, only death or extinction awaits them.
After 2006, the Zetsian toad in the Panamanian rainforest was almost completely wiped out. Conservationists captured and protected the remaining population; although it was scarce at the time, it was the only hope of retaining the species. To this day, at least 500 Zephyllus toads have been successfully bred under artificial conditions, but they will never be able to return to their rainforest homeland – until the effects of chytrid disease are minimized.
Artificially bred Zetsian spotted toad | The lord of allosaurs / Wikimedia Commons
The road ahead is unpredictable
From sporadic to large-scale outbreaks, chytridiosis is arguably an emerging infectious disease (EID) in the animal kingdom. In the last two decades or so, many human infectious diseases have also increased dramatically like chytridiosis and will continue to increase in the future. Together, they weave a special "map of the world."
Map of emerging infectious diseases in the world (2017) | Antony Fauci
The person who drew and updated this map of the disease was Anthony Fauci.
Emerging infectious diseases often ignore geographical constraints and require only effective transmission between the initial few people to develop into a public health event affecting the world. In addition to international trade, climate change, ecological destruction, bacterial resistance, and the many backwardness and injustices brought about by poverty can fuel the growing fire of infectious diseases.
The fate of the Zee's spotted toad rests on the hands of humans| Brian Gratwicke / Wikimedia Commons
Scientific research, cross-regional cooperation, on a grand scale, the struggle between human beings and infectious diseases has never stopped; and for ordinary people, not to carry animals and plants into and out of the country, to refuse unguarded informal trade, is within their ability.
"Infinite distances, countless people, all related to me." And, of course, this includes the current global pandemic.
The Zephyllum toad display area at the Maryland Zoo | Brian Gratwicke / Wikimedia Commons
Zetsi is a toad endemic to Panama and has another name, the Panamanian Golden Frog. According to local legend, the dead Zetsch toad will turn into gold, bringing good luck to those who encounter it. However, as of now, Zetsch toad has not been able to have its own luck.
Can we have our own good fortune?
This article is from the species calendar, welcome to forward
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