<p><strong>Scientist Kris Helgen holds an Eastern long-beaked echidna in <a id="aott" title="Indonesia" href="http://travel.nationalgeographic.com/travel/countries/indonesia-guide/">Indonesia</a>'s <a id="ecpx" title="Foja Mountains (map)" href="http://maps.nationalgeographic.com/map-machine#s=r&amp;c=-2.7510175647965727, 138.95782470703125&amp;z=8">Foja Mountains (map)</a> in a file picture. The elusive egg-laying species is one of the rarest and most genetically unique <a id="hzo2" title="mammal" href="http://animals.nationalgeographic.com/animals/mammals/">mammals</a> on the planet, according to the Zoological Society of London's <a id="o8qr" title="2010 EDGE (Evolutionarily Distinct, Globally Endangered) list" href="http://www.edgeofexistence.org/">2010 EDGE (Evolutionarily Distinct, Globally Endangered) list</a>, released November 19. </strong>(<a id="ujgb" title="Take an endangered-animals quiz." href="http://animals.nationalgeographic.com/animals/endangered-animals-quiz/">Take an endangered-animals quiz.</a>)</p><p>Of the 100 species on this year's list, 49 are new additions since the last EDGE update, in 2007—and some may already be extinct. In addition to the Eastern long-beaked echidna, the Western long-beaked and Attenborough's long-beaked echidna topped EDGE's list this year. All three—and most of the other EDGE species—are deemed critically endangered by the <a id="y6wz" title="International Union for Conservation of Nature (IUCN)" href="http://www.iucn.org/">International Union for Conservation of Nature (IUCN)</a>.</p><p>The EDGE project calculates a score for a species' uniqueness by looking at a so-called supertree, a "huge family tree showing the evolutionary relationships between all mammals," said <a id="hifm" title="Carly Waterman" href="http://www.edgeofexistence.org/community/member_info.php?id=2">Carly Waterman</a>, program manager for EDGE. That number—combined with the animal's scarcity according to the IUCN—determines a species' rank on the EDGE list. ZSL created a separate <a id="m_oc" title="EDGE list for weird and rare amphibians" href="http://www.edgeofexistence.org/amphibians/top_100.php">EDGE list for weird and rare amphibians</a>.</p><p>Though a 2010 expedition to Indonesia's Papua Province did not reveal any live echidnas, the team did find telltale holes that the creatures poke in the earth while searching for worms.</p><p>"And everybody we spoke to that had encountered one had eaten one," Waterman said. "Every single person said they're really, really tasty." (Related: <a id="n53:" title="&quot;New Snub-Nosed Monkey Discovered, Eaten.&quot;" href="http://news.nationalgeographic.com/news/2010/10/101027-snub-nosed-monkey-sneezes-new-species-science-discovered-eaten/">"New Snub-Nosed Monkey Discovered, Eaten."</a>)</p><p>While experts suspect that hunting is the biggest danger to echidnas, "we don't really know what the relative impacts of the threats are," Waterman added.<em></em></p><p><em>—Rachel Kaufman</em></p>

1-3: Three Long-Beaked Echidnas

Scientist Kris Helgen holds an Eastern long-beaked echidna in Indonesia's Foja Mountains (map) in a file picture. The elusive egg-laying species is one of the rarest and most genetically unique mammals on the planet, according to the Zoological Society of London's 2010 EDGE (Evolutionarily Distinct, Globally Endangered) list, released November 19. (Take an endangered-animals quiz.)

Of the 100 species on this year's list, 49 are new additions since the last EDGE update, in 2007—and some may already be extinct. In addition to the Eastern long-beaked echidna, the Western long-beaked and Attenborough's long-beaked echidna topped EDGE's list this year. All three—and most of the other EDGE species—are deemed critically endangered by the International Union for Conservation of Nature (IUCN).

The EDGE project calculates a score for a species' uniqueness by looking at a so-called supertree, a "huge family tree showing the evolutionary relationships between all mammals," said Carly Waterman, program manager for EDGE. That number—combined with the animal's scarcity according to the IUCN—determines a species' rank on the EDGE list. ZSL created a separate EDGE list for weird and rare amphibians.

Though a 2010 expedition to Indonesia's Papua Province did not reveal any live echidnas, the team did find telltale holes that the creatures poke in the earth while searching for worms.

"And everybody we spoke to that had encountered one had eaten one," Waterman said. "Every single person said they're really, really tasty." (Related: "New Snub-Nosed Monkey Discovered, Eaten.")

While experts suspect that hunting is the biggest danger to echidnas, "we don't really know what the relative impacts of the threats are," Waterman added.

—Rachel Kaufman

Photograph by Tim Laman, National Geographic

Pictures: 14 Rarest and Weirdest Mammal Species Named

From echidnas to hairy-nosed wombats, see ten of the rarest and weirdest mammals on Earth, as ranked by the Zoological Society of London.

Read This Next

The science behind seasonal depression
These 3,000-year-old relics were torched and buried—but why?
How the Holocaust happened in plain sight

Go Further

Subscriber Exclusive Content

Why are people so dang obsessed with Mars?

How viruses shape our world

The era of greyhound racing in the U.S. is coming to an end

See how people have imagined life on Mars through history

See how NASA’s new Mars rover will explore the red planet

Why are people so dang obsessed with Mars?

How viruses shape our world

The era of greyhound racing in the U.S. is coming to an end

See how people have imagined life on Mars through history

See how NASA’s new Mars rover will explore the red planet

Why are people so dang obsessed with Mars?

How viruses shape our world

The era of greyhound racing in the U.S. is coming to an end

See how people have imagined life on Mars through history

See how NASA’s new Mars rover will explore the red planet