Eastern long-beaked echidna

EDGE score: 6.8



Found only in New Guinea, the eastern long-beaked echidna ranks first on the EDGE list of mammals – tied with the western long-beaked echidna and the Attenborough's long-beaked echidna. All are distinguished by their long snouts, bristling with electro-receptors that allow them to detect weak electrical fields produced by their prey (earthworms, mostly). They do not have teeth. Instead, their tongues are covered in spikes to hook and draw food into their mouths.



When threatened by predators, the eastern long-beaked echidna raises the spikes on its back and either burrows into the soil to protect its soft belly, or curls up in a spiky ball like a hedgehog.



(Image: Tim Laman/National Geographic Creative)

Mountain pygmy possum

EDGE score: 6.29



The mountain pygmy possum is a small, rodent-like marsupial that lives only in the mountains of south-east Australia. Although this critter thrives in warm summer weather, feeding on tasty moths and other arthropods, it also depends on yearly winter snowfall for hibernation. With global warming, it has been forced to live at ever higher altitude to ensure a thick snowy blanket to curl up under.



Females build communal nests and share their territory. They give birth to four live young, which remain in their mother's pouch for several weeks before being transferred to the nest. With unusually long lifespans for their size, mountain pygmy possums have been known to live up to 12 years.



(Image: Tim Laman/National Geographic Creative) Advertisement

Sumatran rhino

EDGE score: 6.19



Its two horns, hairy body and relatively small size are what distinguish the Sumatran rhino from its four remaining relatives. It is the only surviving member of a primitive rhino group that arose 15 to 20 million years ago, thought to be closely related to the extinct woolly rhinoceros. Today, the Sumatran rhino occupies a narrow range but in the past it was widely distributed and is in fact more closely related to the two surviving rhinoceros species in Africa than to those in Asia.



Sumatran rhinos are agile climbers. An adult eats around 50 kilos of food a day, feeding mostly on saplings, but enjoying everything from bamboo to figs and mangos.



(Image: Joel Sartore/National Geographic Creative)

Kakapo

EDGE score: 6.28



Not your typical parrot, the kakapo is flightless, nocturnal and unusually large. They can weigh in at up to 3.6 kilos after increasing their bodyweight by 60 to 100 per cent in preparation for breeding. The males have a booming low-pitched mating call to match their heft.



A native New Zealander, the kakapo is now extinct in its natural range. Having evolved with few predators, it did not fare well when humans arrived bringing rats and dogs. This, together with hunting, forest burning and the environmental degradation caused by the introduction of new herbivores, caused a catastrophic decline in kakapo numbers. After translocation on to three small islands and an intense conservation effort, the population now stands at 125 individuals.



(Image: Frans Lanting/National Geographic Creative)

Kagu

EDGE score: 6.11



The kagu is known as the "ghost of the forest" on its native isle of Grand Terre in New Caledonia. It is nearly flightless and its ashy white hue is unusual for a forest-dweller. It possesses powder-down made of specialised feathers that degrade into particles to keep it dry and insulated – a feature more commonly seen in parrots. Unlike any other bird, the kagu has nasal flaps over its nostrils. With no definite relatives, it has been placed in a family all its own.



Kagus are carnivores and highly territorial, sometimes engaging in vicious fights with one another. They were once thought to live in isolated, monogamous pairs, but recent research suggests they may breed cooperatively.



(Image: Biosphoto, Nicolas-Alain Pet/Biosphoto/FLPA)

Philippine eagle

EDGE score: 5.98



The national bird of the Philippines, the Philippine eagle used to be called the monkey-eating eagle, based on the belief that it preyed only on primates. Recent studies have shown it has a far more varied diet, including rodents, bats, monitor lizards and pigs.



Although it is one of the largest and most powerful birds of prey, Philippine eagles are lovebirds with their partners. They mate for life and they share parental duties for the 20 months it takes to raise their fledglings. Each breeding pair needs an expansive 40 to 80 square kilometres to feed and rear a chick, making them particularly susceptible to deforestation.



(Image: Klaus Nigge/National Geographic Creative)

Chinese giant salamander

EDGE score: 7.21



The Chinese giant salamander lives up to its name: it is the world's largest amphibian, reaching up to 1.8 metres in length. Aquatic throughout its life, it occupies cool, fast-flowing streams and mountain lakes, feeding mostly on fish and crustaceans. Under pressure, however, these guys will eat almost anything, including their own shed skin and eggs.



Since the 1960s the population has declined by an estimated at 80 per cent. This is partly due to habitat destruction, but mostly because the giant salamander is considered a delicacy in China and is an important source of traditional medicine. Overexploitation was perhaps inevitable as the meat fetches a good price and the salamanders are very easy to catch.



(Image: Natural Visions/Alamy)

Purple frog

EDGE score: 6.77



Surviving the extinction of the dinosaurs and the splitting of a continent, the purple frog, found in Western Ghats range of India, is the only surviving member of a lineage that has been evolving for over 130 million years.



These not-so-pretty frogs live underground most of the year, only surfacing for two weeks during the monsoon season to mate. Their toes are barely webbed, ending instead in round wart-like nodules that are better suited for digging than swimming. By living close to termite colonies, they benefit from a consistent diet of their favourite food, and the insect's mounds keep the underground soil temperature low and moisture content high, providing the perfect purple frog habitat.



(Image: CC-BY-SA-3.0)