The ESA is the most significant piece of endangered species legislation, having prevented the extinction of 99 percent of the species it protects since its inception in 1973.

Today, the Endangered Species Act protects more than 1,400 U.S. species and 600 foreign species.

Unfortunately, nine species from the list have gone extinct. Just 14 have recovered enough to be removed.

Technically all of these were among the first species to be protected under the 1966 Endangered Species Preservation Act, but only the Timber Wolf is a mammal. The Whooping Crane is categorized as a bird and the American Alligator as a reptile or amphibian.

The Kemp's Ridley Sea turtle is critically endangered, with an estimated population of about 1,000 females in the world.

True. In 2008, the polar bear was listed as threatened due to the continuing loss of Artic sea ice.

Thankfully, no cat has gone extinct since the saber-toothed cat nearly 11,000 years ago, but the Iberian lynx is coming close. It's the most endangered cat in the world, with numbers in the low hundreds.

Diseases like the Ebola virus and illegal poachers are decimating what's left of this incredible species.

It's estimated that tigers in the 13 tiger range countries have lost 93 percent of their historical range.

The gray wolf was officially removed from the list in 2013 after its population rebounded by as much as 300 percent.

Conservationists have taken to sawing off the rhinos horns, which are prized by illegal poachers.

The bald eagle was on the Endangered Species list for more than 30 years, but was removed in 2007 after a successful recovery.

Habitat destruction, illegal poaching and introduction of new species are all major threats to endangered species.

Both are ways you can help protect endangered species from extinction.

Estimates place the number of cheetahs at between 10,000 and 15,000, with about 1/10 of those living in captivity.

The Florida Manatee was one of the first mammals listed under the 1966 Endangered Species Preservation Act.

The 1966 Endangered Species Preservation Act included nearly twice as many birds than mammals.

The Javan rhinoceros is the most endangered of the world’s five rhinoceros species, with an estimated 40 to 60 animals remaining on the western tip of the Island of Java in Indonesia.

Whales are drowning after becoming wrapped in commercial fishing gear. Although, with global climate change, the availability of food is also proving to be another serious threat to their recovery.

The saola is related to cattle and resembles an antelope with brown and white patches on its head and face and spindly horns. It was first discovered in 1992 and has been seen just a few times since.

A few sightings of the ivory-billed woodpecker in Arkansas and Florida have trickled in, but there's still no solid evidence of the ivory-bill’s continued existence. If a population does exist, it is likely to be tiny and extremely vulnerable.

President Richard Nixon signed it into law in 1973.

The Endangered Species Act of 1973 replaced the Endangered Species Conservation Act of 1969.

The Convention on International Trade in Endangered Species (CITES) is one of the largest environmental agreements regulating the international trade in wildlife.

True. CITES has a voluntary agreement and it currently includes 181 member states.

True. The illegal wildlife trade is estimated to be worth $7 billion to $23 billion, making it the third-largest illegal trade by dollar value, after drugs and guns.

Both poaching and trade in tiger parts and products is a major threat to wild tiger survival.

The ESA proposed delisting three subspecies of island fox native to California’s Channel Islands: the San Miguel, Santa Rosa and Santa Cruz Island fox. The removal would be the fastest recovery for any mammal on the Endangered Species List in the United States.

Just five species of rhino still exist on earth — the white rhino, the black rhino, the great-horned rhino, the Sumatran rhino and the Javan, all of which are endangered.

Just 1 percent of African elephants — approximately 600,000 — survived when they were added to the international list of the most endangered species in 1989.