While all Gorilla species are vulnerable, the Cross River Gorilla is the most endangered great ape in the world. Unfortunately, the Cross River Gorilla, which was first noted in 1904, was largely ignored until it was too late in 1987 and its population numbers were already low. Today, it is estimated that there are less than 250 Cross River Gorillas in the wild and only one known to be in captivity. The biggest threat to the survival of the Cross River Gorilla is habitat loss due to human activities. Also, the Cross River Gorilla is threatened by bushmeat hunting by locals. Due to the hunting, Cross River Gorillas are very fearful of humans and are very rarely observed. Have you ever heard of Cross River Gorillas?

Cross River Gorillas live in highlands on the border of Cameroon and Nigeria in small, scattered groups that rarely, if ever, interact with one another. This has led to inbreeding. This results in a loss of genetic diversity, a weaker gene pool and also negatively impacts the already small population of remaining Cross River Gorillas. Are you concerned about the future viability of these rare gorillas?

Of all the animals on this list, none are as mysterious as the Saola, which has been aptly dubbed the "Asian Unicorn." So little is known about the Saola that there is no real data on the elusive animal's current population. Because the Saola has only been seen in the wild a handful of times since its remains were first discovered in 1992, population estimates wildly vary from as little as 25 individuals to as many as 750. However, researchers believe that the Saola population is much lower, and most likely less than 250. Were you familiar with Saola before this survey?

Most of the information known about the Saola comes from William G. Robichaud, who managed to keep a female Saola in captivity for about 15 days before she died of unknown causes. According to Robichaud's observations, the Saola was not afraid of humans, only dogs. All other efforts at a captive breeding program have failed. Are you concerned about the future of Saola?