12 rare animals that are teetering on the brink of extinction

Every day, species around the planet are going extinct. And for each species that goes extinct, many more become and remain endangered due to habitat loss, poaching, human activities, and climate change. Some are so critical that they are teetering on the brink of extinction.

All these threatened animals are included on the International Union for Conservation (IUCN) Red List of Threatened Species, a non-prescriptive list that is the world's most comprehensive inventory of the global conservation status of species.

"The IUCN red list tells us how close to extinction species are," Craig Hilton Taylor, head Red List Unit of the Global Species Programme at the IUCN, told Business Insider. "It is a fairly coarse measure [but] we have a set of quantitative criteria that we try to rank species under, and if a species moves into one of the threatened categories - vulnerable, endangered, or critically endangered - then we know that a species either has a high, very high, or an extremely high risk of going extinct in the wild unless we do something about it."

For example, he said, polar bears are considered vulnerable to extinction, while tigers are endangered (a more critical category), and just this July, the IUCN declared that the Bornean orangutan critically endangered.

Here are 12 species at risk of extinction, including some that you probably didn't even know existed.