- Djoko Tjahjono Iskandar has spent nearly 50 years exploring rural Indonesia in pursuit of novel frog species.
- Indonesia is home to almost 10% of around 6,000 known species of frogs in the world; however, scientists warn half of amphibians worldwide could be lost without urgent action.
- The archipelago of 270 million people also accounts for a majority of the world’s exports of frogs’ legs to Europe and other regions, most of which are caught in the wild.
BANDUNG, Indonesia — Nearly 50 years have passed since Djoko Tjahjono Iskandar began his early scientific expeditions to uncover new species hidden across Indonesia. In that time, Djoko has described several of the 400 species of frogs so far cataloged in the world’s largest archipelagic country.
“Ever since I began my research in 1975, I have always been drawn to the conclusion that the universe was created as unique,” Djoko told Mongabay Indonesia at the Bandung Institute of Technology (ITB), the university where he started teaching 45 years ago.
Over the course of his career, Djoko has waded through marshes in Sumatra, hiked forests in Java, ascended peaks in Sulawesi, tracked rivers in Borneo, and led expeditions through Papua — covering a remarkable amount of ground across Indonesia’s 17,000 islands.
“I usually start by tracing a river,” he said.
Djoko counts several species descriptions made during his five-decade career for which he was named, from lizards such as Gekko iskandari in 2000 and Draco iskandari in 2007, to frogs like Fejervarya iskandari in 2001.
Born in Bandung on the island of Java, Djoko published Amphibians of Java and Bali in 1998, widely seen as the successor to The Amphibia of the Indo-Australian Archipelago, published in 1923 by Dutch zoologist Pieter van Kampen. Djoko’s book featured 35 newly described frog species. To date, he has 163 publications and more than 20 books to his name.
In Kalimantan, the Indonesian portion of the island of Borneo, Djoko located Barbourula kalimantanensis, a frog without lungs that breathes through its skin, which had eluded researchers for years. On the island of Sulawesi, he described another frog species, Limnonectes larvaepartus, where the female gives birth to live tadpoles instead of laying eggs in a body of freshwater.
“Frogs themselves display such a wide variation in reproductive processes from evolution and diversification,” Djoko told Mongabay Indonesia.
Croak and dagger
Amphibians face a dangerous array of threats to their survival in the medium term, from habitat destruction and invasive species, to climate change, pollution, and demand for meat.
Data from Indonesia’s Ministry of Agriculture recorded the value of the nation’s frog exports at around $22.5 million per year. Experts say almost all of these frogs are caught in the wild for their legs, the meatiest part of the animal. Most have their legs amputated while they’re still alive.
In 2022, European NGOs Pro Wildlife and Robin des Bois published a report detailing the extent of the European market for frogs’ legs, a delicacy in parts of Western Europe and China.
“If the plundering for the European market continues, it’s highly likely that we will see more serious declines of wild frog populations and, potentially, extinctions in the next decade,” Pro Wildlife co-founder Sandra Altherr said in a statement.
The report estimated that Indonesia was the source country for 74% of European imports of frogs’ legs, a large majority of which are sent to Belgium.
“Actually, this has been happening for a long time,” Djoko said.
The Amphibian Survival Alliance, the world’s largest amphibian conservation coalition, projects that half of all amphibian species could be lost in the coming decades without “immediate and coordinated action” to strengthen landscape and species protection.
“Amphibians are the most threatened vertebrate class on Earth, with 41% of species threatened with extinction,” according to the Amphibian Specialist Group at the IUCN, the global wildlife conservation authority.
For Djoko, the study of frogs offers both a window to our past and a glimpse of a worrying future. Scientists can parse the loss of frog populations, he said, to infer detailed realities as to the health of an environment.
“Amphibians might be an indicator to measure the extent of the impact of climate change,” he said.
Mongabay Indonesia met Djoko in a laboratory at ITB’s biology department in mid-January. Classes hadn’t resumed yet after the holidays, so the campus halls were quiet.
Djoko had recently published a paper on Limnonectes phyllofolia, a newly described species of fanged frog in Sulawesi, whose eggs are guarded by the male until they grow into tadpoles.
Djoko unlocked his cellphone and began flicking through photographs taken from his expeditions to all but two of Indonesia’s provinces — only the capital, Jakarta, and Bangka-Belitung, a clutch off islands off Sumatra’s eastern coast, haven’t been the sites of Djoko’s research trips.
About 1.6 million species have been identified and cataloged by science to date, and around 18,000 species are described every year, according to the U.K.’s Royal Society, the world’s oldest academy of sciences. Unidentified species are estimated to account for around 80% of all species on Earth.
Despite having spent half a century exploring the world’s largest archipelagic country hoping to discover new frogs, Djoko said he believes his life’s work is far from complete.
“I worry sometimes when I see the current state of research,” he said. “Research in Europe is 100% finished: they have researched everything [that they have].
“For us, it’s only 20%, but it’s already considered finished — and yes, it has to be acknowledged that our research progress is minimal,” he said.
Today, he’s focused on writing a paper on how evolution has proliferated a kaleidoscope of biodiversity throughout Indonesia. He wants frogs to capture the imagination of Indonesian and international readers, and for greater attention to be paid to the viability of amphibian species.
“Isn’t it everyone’s duty to give meaning through their research, to look for new ideas, and relate these to the public?” Djoko said. “I think that is the essence of knowledge for life.”
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