Millions of rhinos once roamed the Earth. There were hundreds of species of all shapes and sizes. But today, the rhinoceros is one of the planet's rarest animals, with three of its species on the brink of extinction. While there is still a chance to save them, teams of experts work to protect rhinos from poachers, relocate them to better habitats, and breed them in captivity.

Sunday, 5/18/08 from 8-9 p.m. ET
Thursday, 5/22/08 from 4:30-5:30 a.m. ET