These are some of the wildlife populations in danger of becoming extinct if drastic conservation measures are not taken.
Native to the deserts and grasslands of Namibia and Coastal East Africa, the black rhinoceros is one of the oldest mammals on Earth. The World Wildlife Fund calls them "virtually living fossils."
They play an important role in their habitats and as a source of income for their native countries through ecotourism. Yet, conservationists have been fighting an uphill battle to save them.
Black rhinos have two horns, which makes them especially attractive to poachers engaged in the illegal trade of rhino horn. Between 1970 and 1992, a staggering 96 percent of Africa's remaining black rhinos were killed for this purpose, rendering them a critically endangered species. There are less than 4,900 surviving in the world.
Yangtze finless porpoise
Yangtze finless porpoises are one of two species of dolphins, who made their homes in Asia’s Yangtze River. In 2006, however, that other species, the Baiji dolphin, was declared functionally extinct, due to the destruction of its food supply by human interference.
Finless porpoises, known for their mischievous smiles and their gorilla-level intelligence, require an ample food supply to survive. And much like the food supply of the Baiji dolphin, it is now threatened by overfishing, pollution and ship movement.
The World Wildlife Fund is currently working to reconnect more than 40 floodplain lakes with the main stem of the Yangtze River to restore seasonal flows, before these critically endangered creatures become the second species of dolphin to be wiped off the Earth completely because of humans.
A baby mountain gorilla from the family known as Amahoro, which means “peace” in the Rwandan language, is held by its mother in the dense forest on the slopes of Mount Bisoke volcano in Volcanoes National Park, northern Rwanda.
These days, an estimated 900 mountain gorillas, a subspecies of the eastern gorilla, live in the steep-sloped forests of Rwanda and neighboring Congo and Uganda, the last of their species on earth. The population has suffered from poaching, civil unrest -- including the war in Rwanda in the 1990s and years of conflict in the Democratic Republic of Congo -- as well as the loss of their natural habitats to humans.
They are listed as a critically endangered species by the World Wildlife Fund though their numbers have increased slightly in recent years because of conservation efforts.
The eastern gorilla, made up of two subspecies--Grauer’s gorillas and eastern gorillas, was listed as critically endangered by the IUCN in Sept. 2016, after a population decline of more then 70% in 20 years. It is now believed there are less than 5,000 in total in the world.
More photos: Gorillas in Rwanda
South China tiger
This South China tiger was born in captivity. Once estimated at a population of 4,000 in the 20th century, they are believed to be extinct in the wild now, without a single sighting for more than 25 years. According to the World Wildlife Fund, they dwindled from 4,000 in the 1950s to just 30-80 by 1996. One of the most critically endangered species with the only ones alive in captivity.
Northern white rhino
While the species of white rhinos as a whole is considered “near threatened,” the sub-species of northern white rhinos is severely endangered. There are only five members of this sub-species left on the planet.
Sudan, seen here, is the only remaining northern-white rhino male in the world. He and his two female companions, Suin and Fatu, live at the ol-Pejeta sanctuary in Kenya’s Mt. Kenya region. With only one male left, the future of northern white rhinos now depends solely on artificial methods of reproduction.
Unlike other leopards that live in the savannas of Africa, Amur leopards make their homes in the temperate forests of Eastern Russia. They can run up to 37 miles per hour, leap more than 19 feet horizontally, and live up to 15 years (20 in captivity).
Amur leopards are also unique in that the males often stay with females after mating, even helping to raise their young. Sadly, there are only around 60 Amur leopards left. In fact, this subspecies of leopard is considered one of the most critically endangered felines in the world.
The biggest threat to the Amur leopard is the illegal wildlife trade. They are poached for their beautiful, spotted fur. A male leopard skin can fetch up to $1,000 in Russia.
In December 2016, the International Union for the Conservation of Nature (IUCN) added giraffes to its official watch list of threatened and endangered species worldwide, calling them “vulnerable.” The group said habitat loss is largely responsible.
“There’s a strong tendency to think that familiar species (such as giraffes, chimps, etc.) must be OK because they are familiar and we see them in zoos,” said Duke University conservation biologist Stuart Pimm, who has criticized the IUCN for not putting enough species on the threat list. “This is dangerous.”
The Sumatran orangutan lives amidst the trees of tropical rainforests. They once lived throughout Sumatra, but now their habitats are mainly found in North Sumatra and Aceh.
The species is currently listed as critically endangered by the WWF, with only an estimated 7,000 remaining. Efforts are being made to reintroduce orangutans rescued from illegal trade or being kept as pets into the wild.
The Bornean orangutan is listed as endangered.
More photos: Orangutans in jeopardy
Sumatran elephants live in the forests of Borneo and Sumatra, where they travel in herds and feed on a variety of plants and deposit seeds. They are about 20 feet long and weigh approximately five tons.
These majestic creatures are critically endangered due to the destruction of their habitat by the logging, palm oil and rubber industries in Asia. Over two-thirds of the species’ lowland forest habitat has been razed in the last 25 years and nearly 70 percent of its natural habitat destroyed in just one generation. This has resulted in the animals invading local villages, destroying homes and crops. Forest rangers and activists from the Wildlife Conservation Society are trying various methods to return them to the forest, including training them to keep away and hunting for illegal loggers. There are currently between 2,400 and 2,800 of the mammals left, confined to small patches of forest.
Because only male Sumatran elephants have tusks, poaching has drastically skewed the sex ratio of this species, severely threatening breeding rates.
Cross river gorilla
Cross river gorillas live in the lowland mountain forests and rainforests of Cameroon and Nigeria, areas heavily populated by humans as well. As such, the gorillas’ territory has been threatened by poaching, clearing for timber and the creation of fields for agriculture and livestock.
Cross river gorillas can reach up to five-and-a-half feet tall and 440 pounds. They are considered critically endangered, with less than 300 of their kind left.
Western lowland gorilla
The western lowland gorilla can be found in the Central African Republic, Cameroon, the Democratic Republic of Congo Equatorial Guinea, Gabon and the Republic of Congo. They differ from other gorilla subspecies in that they are somewhat smaller with brown-grey coats and auburn colored chests.
Their total population isn’t known, but it is estimated that, primarily due to poaching and disease, their numbers have dwindled by at least 60% over the past two decades. They are listed as critically endangered by the WWF.
Pangolins are primarily nocturnal animals that can curl up into a ball when startled and use their scales to lash out at predators. Often mistaken as reptiles, they are actually mammals covered neck-to-toe in a body armor of scales.
Pangolin meat is considered a delicacy in both Asia and Africa. The animals’ scales are also utilized in a range of folk remedies for conditions like asthma and arthritis. As such, pangolins have become one of the most trafficked mammals in the world.
Two pangolin species are now listed as critically endangered on the IUCN Red List of Threatened Species.
For millennia, the snow leopard ruled the mountains of China, Bhutan, Nepal, India, Pakistan, Afghanistan, Russia, and Mongolia. It could scale steep slopes with ease, leap six times its body length and wrap its tail around its body to protect itself from the cold.
In recent years, however, this powerful cat has become endangered due to several forms of conflict with its sole predator, humans.
Animals that snow leopards traditionally hunt, like Argali sheep, are now also hunted by humans and, therefore, harder to come by. This has forced snow leopards to start killing livestock to survive, which has in turn caused local farmers to begin killing snow leopards to protect their livestock. These retaliatory killings, combined with habitat fragmentation and climate change, have diminished snow leopard populations to somewhere between 4,080 and 6,590.
The sperm whale, made famous by “Moby Dick,” is the largest of all toothed whales. Male sperm whales can grow to be more than 60 feet long and females up to about 40 feet. They live, on average, around 70 years and traverse all of the world’s oceans, plus the Mediterranean Sea.
While these torpedo-shaped mammals once numbered about 1.1 million worldwide, whaling diminished their population from the end of World War II through 1985, as hunters raced to extract oil from the reservoirs in their massive heads and render it from their blubber. Now protected by the Endangered Species Act, their numbers are still recovering with around 300,000 of them in existence.
There is also a distinctive population of sperm whales living in the Gulf of Mexico that scientists fear may be adversely affected by the Gulf Oil Disaster and all of the toxic fumes and chemical dispersants spread throughout their habitat.
In this photo, a woman approaches the carcass of a 50-foot sperm whale washed ashore on the Pacifica Beach near San Francisco, April 15, 2015.
African wild dog
The African wild dog is one of the world’s endangered mammals. Ranging from 40 to 70 pounds, these animals gather in packs and hunt medium-sized animals of opportunity, at speeds of more than 44 miles per hour.
The African wild dog population is currently estimated at somewhere between 3,000 and 5,000. Its numbers are dwindling due to viral diseases like rabies and distemper, habitat loss, and competition from larger predators like lions.
Cheetahs are the fastest land mammals on Earth, possessing the ability to accelerate from zero to 64 miles per hour in just three seconds. However, they’re small and they can’t sustain those speeds for long, which makes them susceptible to larger predators like hyenas and lions. In fact, cheetahs will often surrender a kill to one of these predators to avoid a fight.
Male cheetahs will form groups of two or three and remain together for life. Female cheetahs are more solitary. They are threatened by both the growing scarcity of suitable habitats and the illegal trade in cubs as pets.
While cheetahs as a whole are considered “vulnerable,” the Asiatic and Northwestern Saharan subspecies are listed as Critically Endangered. Their numbers are thought to be between 60 and 100, making them some of the most endangered cats on the planet.
Leatherback turtles are the largest and most migratory sea turtles in the world. They cross both the Atlantic and Pacific Oceans to feed, and their Pacific and Southwest Atlantic subpopulations are considered critically endangered by the WWF.
Named for their unique shells, which are more leather-like than hard, these turtles grow up to 63 inches long and 1500 pounds. They are a fundamental link in marine ecosystems and help keep jellyfish populations in check.
Sadly, though, Leatherback turtles are at risk of extinction due to intense egg collection and fishery bycatch.
There are only 400-500 Sumatran tigers, the smallest tiger subspecies left. They have heavy black stripes and orange coats.
Deforestation and poaching are the biggest threats. The market for tiger parts and products has a big impact on the survival of this critically endangered species as well.
Bonobos look like smaller, leaner, darker chimpanzees. Like chimpanzees, they share 98.7 percent of their DNA with humans, making them one of our two closest living relatives in the animal kingdom.
As primates go, bonobos live in relatively peaceful groups led by females. They maintain long relationships and settle conflicts with sex. Wild bonobos are found in the forests of the Congo Basin.
Years of civil unrest and poverty in the Democratic Republic of Congo have hampered scientific study of this species, and contributed to both bonobo poaching and the harmful deforestation of their habitats. As such, these animals are now considered endangered with less than 50,000 remaining.
Asian or Malayan tapir are the largest of the four species of tapir and are found in the lowland rainforests of Southeast Asian. They are distinguished by a light-colored patch, which extends from their shoulders to their rear ends, acting as a sort of camouflage. When lying down, this patch leads other animals to mistake Asian tapir for large rocks rather than prey.
Despite their poor eyesight, Asian tapir have few natural predators. Thanks to their size (between 550 and 710 pounds), it’s even rare for tapir to be killed by tigers.
The animals are primarily threatened by deforestation for agricultural purposes, illegal wildlife trade, and flooding caused by the damming of rivers for hydroelectric projects. In short, this is yet another species endangered by human activity.
The Hawksbill sea turtle gets its name from its pointed beak. Their colored and patterned shells are frequently sold as “tortoiseshell,” making them highly valued commodities.
They can often be found around the world in coral reef areas, but are critically endangered.
Saola were first discovered in Vietnam in May 1992. Since then, the elusive animal has only been documented in the wild on four occasions.
Saola have two distinctive parallel horns with sharp ends that can reach up to 20 inches in length. Ranging from 176 to 220 pounds, these animals reside in the evergreen forests of Vietnam and Laos, which have little to no dry season.
Affectionately known as the Asian unicorn, Saola resemble antelopes, but have striking white markings on their face. Because they are so rarely seen, it is difficult to estimate their current numbers. However, scientists believe there are only a few hundred left at most, possibly only a few dozen remaining. As their forest habitat disappears to make way for agriculture, plantations and infrastructure, these critically endangered creatures are being squeezed into smaller and smaller tracts of land, where they are less and less protected from hunters.
Vaquita, the rarest marine mammals in the world, live in the Gulf of California and are most often spotted in the shallow waters near the shore. They are small porpoises with large dark rings around their eyes and dark patches on their lips.
Vaquita were only discovered in 1958 and now, due to fishery bycatch, they are on the brink of extinction. Nearly one out of every five Vaquita become entangled and ultimately drown in gillnets intended for other animals. Now, there are less than 100 of these animals left.
An addax is a pale antelope with long, twisted horns that can reach up to 33 inches on males and 31 inches on females. Its coat grows darker in the winter and lighter in the summer. This mammal is uniquely equipped for arid climates with sandy or stoney deserts because it can survive for long periods of time without water.
Once abundant in Northern Africa, the addax is now extinct in Algeria, Egypt, Libya, Sudan and the Western Sahara. It has been reintroduced in Morocco and Tunisia, but is listed as critically endangered on the IUCN Red List of Threatened Species. The addax is not a terribly fast animal, making it a relatively easy target for predators like lions and cheetahs.
Here, an addax calf born June 7, 2013 roams the enclosure at Brookfield Zoo on July 2, 2013 in Brookfield, Illinois. About 200 of the nearly-extinct addax live in North American zoos. As of 2013, only about 300 still survived in the wild.
San Joaquin Kit Fox
The San Joaquin kit fox is one of the most endangered animals in California. Once abundant throughout the state’s San Joaquin Valley, the creatures are now only found along its edges.
The size of a house cat, the San Joaquin kit fox is distinguished by its yellowish-grey fur, big ears and long bushy tail. Primarily active at night, these tiny foxes live in underground dens and survive off of rodents, birds, lizards and other small animals like cottontails. They don’t need to drink water because they can absorb all the hydration they need through their prey.
As the open grasslands in California’s Central Valley are converted to farms, homes and roads, it becomes increasingly difficult for San Joaquin kit foxes to survive and find mates. They are also threatened by the state’s severe drought and the outdoor poisons used to kill rodents, like mice, which they then consume. Currently, there are less than 7,000 of these small mammals left in the wild.
Point Arena Mountain Beaver
The Point Arena mountain beaver is one of seven subspecies of mountain beaver, and it is considered the most primitive living rodent. It is stout and compact with small eyes, rounded ears and a distinctive cylindrical stump of a tail.
Among other beavers, the Point Arena mountain beaver is distinguished by its unique black fur and its lack of aquatic tendencies. It has opposable thumbs on each forepaw and long curved claws on each of its digits for digging.
Averaging one foot in length and two to four pounds in weight, these mammals, listed as endangered by the U.S. federal government, are found only in California.
The Baluchistan bear, found in the Baluchistan Mountains of southern Pakistan and Iran, is a subspecies of the Asiatic black bear. It has a cream colored crescent patch on its chest, coarse fur that often appears more reddish-brown than back, and it ranges in size from 200 to 400 pounds.
The Baluchistan bear, sometimes referred to as the Pakistan black bear, has a thinner coat than its brethren because it resides in a much warmer climate. It prefers a diet of local fruits, like figs and bananas.
Once prevalent throughout Baluchistan, the bear’s numbers have been significantly depleted by deforestation and the consequent loss of habit. It is now listed on the International Union for Conservation of Nature’s Red List of Threatened Species.
There’s some good news. Giant pandas, the rarest members of the bear family, were moved from endangered status to “vulnerable” on the IUCN Red list in September 2016. Their population has grown “due to effective forest protection and reforestation.” They’re not safe, though, because climate change is expected to eliminate more than 35% of the bamboo habitat they depend on in the next 80 years.
Pandas live primarily in bamboo forests high in the mountains of Western China, where they each eat between 26 and 84 pounds of bamboo per day.
This peaceful creature is adored worldwide and considered a sort of national treasure in its native country. However, China’s booming economy has been the biggest threat to its habitat and thus, its species.
According to the World Wildlife Fund, “Roads and railroads are increasingly fragmenting the forest, which isolates panda populations and prevents mating. Forest destruction also reduces pandas’ access to the bamboo they need to survive.”
China has established more than 50 panda reserves to help boost population numbers. There are about 1,826 left in the wild.