‘Bizarre’ blob-headed fish and amphibious mouse among 27 new species found in Peru

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Researchers on an expedition in Peru have discovered 27 animal species new to science – among them a “blob-headed fish” and a type of semi-aquatic mouse.

The survey was conducted by Conservation International, an environmental non-profit. It was carried out over a 38-day expedition in 2022 by a team working in the Alto Mayo landscape of northwestern Peru, which covers about 1.9 million acres of forest and agricultural areas and contains a diverse range of ecosystems.

Although the region is densely populated, relatively little has been known about its biodiversity and the health of its ecosystems – with researchers hoping to fill gaps in the data through the survey.

But they were not expecting to unearth so many species new to science: four mammals, eight fish, three amphibians and 10 butterfly species.

When a discovery is considered new to science, it means it has never before gone through the formal scientific process through which new species are given a scientific name.

“We were very surprised to find such high biodiversity in a landscape with so much human influence,” said Trond Larsen, a researcher who led the expedition and directs the Rapid Assessment Program at Conservation International.

Among the most surprising new species was an amphibious mouse with webbed toes – to adapt for life in the water. The group of semi-aquatic rodents to which this mouse belongs is “exceedingly rare” said Larsen, adding that they are “incredibly difficult to find (…) very little is known about the lives of these creatures.”

The researchers found this particular mouse species in just one small patch of swamp forest currently threatened by agricultural practices, making it a high priority for conservation.

The other new mammals the team discovered were a spiny mouse, a short-tailed fruit bat and a dwarf squirrel.

Also described for the first time was the “blob-headed” fish, which gets its name from its enlarged, blob-like head. Fish experts involved with the survey had never seen a feature like this before.

“The blob-headed fish has an incredibly bizarre head that looks almost like a giant swollen nose,” Larsen told CNN. “Scientists have never seen anything like it, and we don’t know what the function of this bizarre blob-like structure is.” One possible theory is that the blob helps the animal detect food, he said – but it “remains a mystery.”

Overall, the survey recorded 2,000 species in the landscape which spans from the Andes to the Amazon and crosses over Indigenous territories, towns and cities. Of those species, 49 are on the International Union for the Conservation of Nature’s Red List – meaning they are at risk of extinction.

The researchers hope that knowing more about the region’s biodiversity will make it possible to implement effective conservation measures in the face of threats posed by de-forestation and agricultural expansion.

And while the discoveries may have been “new to science,” that does not mean they were entirely unknown. The expedition enlisted the help of local indigenous researchers and continues to collaborate with indigenous communities on conservation efforts.

“This Rapid Assessment allows the Awajún (indigenous community) to protect our culture, natural resources and our territory, as we have a deep connection with nature,” said Yulisa Tuwi, an Awajún woman who assisted with the survey’s research on reptiles and amphibians.

“Being part of this research has allowed me to better understand how plants, animals and ecosystems interact with each other, and how this is part of our Awajún cosmovision,” she said in a press release.

“Our main goal is to provide scientific knowledge needed to move conservation forward in a way that works for nature and people,” said Larsen, who added that time is limited to meet global goals for biodiversity conservation.

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