An expedition finds a 'lost' mammal that lays eggs and a shrimp that lives in trees

A scientific expedition to a treacherous mountain range on the island of New Guinea has collected the first-ever photographic evidence confirming the survival of a bizarre, egg-laying mammal. The team also found dozens of undescribed species of insects, as well as newfound arachnids, amphibians and even a shrimp that dwells in trees.

This rediscovered mammal, known as Attenborough's long-beaked echidna and named for Sir David, has "the quills of a hedgehog, the snout of an anteater and the feet of a mole," said James Kempton, a biologist at the University of Oxford who led the exploration to the Cyclops Mountains, in the Indonesia province of Papua. Most details about the life history of this critically endangered mammal, which is slightly smaller than a house cat, remain a total mystery.

For years, the echidna was feared extinct. The only prior scientific record of the species was a specimen collected in 1961. "So it is really valuable to understand that it still occurs in the Cyclops Mountains," said Kristofer Helgen, a mammalogist and director of the Australian Museum Research Institute who wasn't involved in the expedition. "To me, these are some of the most special animals on Earth."

This species is one of five living monotremes, a strange group of primitive mammals that includes the platypus and three other echidna species. Monotremes diverged from the common ancestors of other mammals around 200 million years ago. The five species lay eggs and nurse their young with milk through pores in their skin, as they lack nipples, and possess snouts that sense movements and electrical currents in prey.

In a patch of forest toward the top of the Cyclops Mountains, the researchers also found an unusual type of shrimp, slightly larger than grains of rice. These crustaceans were all over the place, including in trees, moss, rotting logs and even under rocks, said Leonidas-Romanos Davranoglou, the expedition's lead entomologist who works at the Oxford University Museum of Natural History.

"It's a very weird creature," Davranoglou said, adding that it's able to leap three or four feet in the air to escape predators. "We were quite awe-struck, really."

There are about nine other species of terrestrial shrimp, all of which live by the shore and are known as beach hoppers. "Our species definitely hops, but it lives nowhere near a beach," Davranoglou quipped.

Near constant rain and steep terrain make the Cyclops Mountains difficult to explore. So do venomous snakes and tree-dwelling leeches. Davranoglou said he had fractured his hand coming down a mountain.

The researchers placed 80 camera traps at various elevations in June and July, and eventually collected 14 photographs and four videos of echidnas. And it wasn't until the last day of the expedition that they discovered they had spotted the echidna. The results were uploaded to the website bioRxiv before submission to a journal for peer review.

Worldwide, there are more than 2,000 "lost species" of plants and animals that have not been scientifically recorded for over a decade. It's vital to know whether such species are still around as human activity accelerates species extinctions, Kempton said.

That's especially true with evolutionarily distinct species like monotremes, he added.

"These five species are the sole guardians of 200 million years of evolutionary history," Kempton said. "To protect that unique and fragile evolutionary history is extremely important."

The scientists found another of these "lost species" toward the top of the mountains when they spotted a pair of Mayr's honeyeaters, lively birds with curved bills and long tails that haven't been documented for 15 years.

Local residents from the village of Yongsu Sapari, on the north side of the mountains, including two guides, Zacharias and Samuel Sorondanya, were crucial to finding species and properly placing camera traps, said Madeleine Foote, an expedition member and social scientist at the University of Oxford. Local students also received biodiversity survey training from the researchers during the trek.

The team plans to name the new species for the local students and collaborators.

During one climb a researcher fell into a moss-covered hole that turned out to be an unknown cave system. Within it the team found blind spiders and crickets, and a large whip scorpion, all new to science, Davranoglou said. The team also found at least three new species of amphibians in the surrounding forest.

Much of the Cyclops Mountains is a nature reserve but surrounding tropical forests face threats such as clearing for agriculture, logging and mining. Iain Kobak, co-founder of Yappenda, a conservation and research foundation based in Papua that helped organize the expedition, said that such explorations would help protect the flora and fauna of the area.

"I really hope and believe this will become a catalyst for strong conservation of the Cyclops Mountain Range," he said.