These mammals were selected because of the degree of danger that they face, and because they have few relatives left alive in the wild -- making them some of the world's most genetically unique mammals.
Ben Collen, a member of the EDGE team, says this makes their preservation particularly urgent.
"These species are unique and irreplaceable," Collen told RFE/RL. "So if they become extinct, there will be nothing else like them on the planet. A lot of these species have very unique, very individual traits which add a lot to biodiversity and ecosystem function."
The Bactrian camel (Camelus bactrianus), for instance, differs from all other mammals in the shape of its blood cells, which are oval instead of circular. There are fewer than 1,000 individuals surviving in the wilds of northwest China and Mongolia -- even. (There are more than 2 million "domesticated" Bactrian camels in Central Asia, but conservationists are careful to distinguish between wild animals in their natural habitat and domesticated animals.)
The onager (Equus onager) is remarkably well adapted to semi-desert regions -- which are hot during the day and cool at night, with little rainfall. It's also the swiftest of all the equids family -- which includes horses, zebras, etc. -- and has been recorded running at speeds of up to 70 kilometers per hour. There are an estimated 570 onagers in two protected areas of Iran.
Some of the species on the list are better known, such as China's giant panda.
...And Lesser-Known Creatures
But many have so far been overlooked -- either because they are in poorly explored regions, they are among species in which scientists have shown little interest, or their habits make them difficult to study.
Such species include two other animals living in Iran: Setzer's mouse-tailed dormice (Myomimus setzeri) and the Iranian jerboa (Allactaga firouzi). The jerboa resembles a mouse, with long hind legs that allow it to jump up to three meters in a single bound. It is known from only a single, small population living on a mountain steppe in southern Iran.
The desert dormouse (Selevinia betpakdalaensis) occurs to the west and north of Lake Balkhash in Kazakhstan. Unlike other dormice, it sheds the upper layers of its skin when it moults.
The head of the Mammals Laboratory at the Kazakh Zoological Research Institute, Amanqul Bikenov, tells RFE/RL that little is known about the desert dormouse.
"In the last 50 years, scientists have been able to catch [just] 40 of them," Bikenov says. "The particularities of this animal [are that] it lives in hiding [and] it is a nocturnal animal. Its biology hasn't been researched yet. For science, this animal is very important; researchers around the world are interested in it."
Many of the species are the only representatives of groups that have otherwise died out.
The saiga antelope -- known for its bulging eyes and a bulbous, tubular nose to filter out dust and warm [or] cold air before it reaches the animal's windpipe -- is the only surviving representative of its genus.
Eleanor Milner-Gulland, a leading expert of the species, has argued for efforts to inform locals on the cultural and economic benefits of saigas.
"They have this great cultural interest. They're a nomadic species [and] they are a symbol of the steppes," Milner-Gulland says. "There's that kind of link between people's heritage and this piece of wildlife. And then, on the...more practical side, the saiga was until 10 years ago a really valuable and productive part of the ecosystem. It produced meat, horn, [and] skins. If the population was large enough, that could start again. There could also be potential for tourism [and] trophy hunting. So the saiga could pay its way if it were allowed to recover as a component of a sustainable steppe that could go on to the future."
The saiga inhabits open dry steppe grasslands and semi-arid deserts in Russia's Republic of Kalmykia, as well as Kazakhstan and Mongolia. Some herds migrate to Uzbekistan and Turkmenistan. Over the last decade, its numbers have plummeted from more than 1 million to around 30,000.
Sense Of Urgency
EDGE team member Collen says the Persian mole (Talpa streeti) -- an animal that runs backward almost as freely as forward -- may already be gone, like some others on the list.
"This is a species that is known from one individual, found in northwest Iran. We urgently need to survey this area to find out whether they still exist."
All the EDGE species are threatened either by hunting or habitat destruction due to human activity.
In close collaboration with local scientists and biodiversity groups, members of the EDGE team will propose conservation plans for each species on the list.
Their goal is to have conservation strategies in place for all 100 species within five years.
Organizers are also reaching out to the public for help. Donors are invited to sponsor a species, and track its conservation progress through blogs and discussion groups on the project's website.
THE FRAGILE PLANET: Since the collapse of the Soviet Union, old environmental disasters have come to light and new ones have emerged. War, poverty, and weak central-government control have led to serious environmental problems from Eastern Europe to the Russian Far East. RFE/RL has provided extensive coverage of these important issues and of efforts to cope with them.