With thousands of species dependent on the Mekong River, many of them yet to be described, the region is one of the most biologically rich and productive regions in the world. The river is home to the critically endangered Mekong giant catfish, as well as a species of freshwater dolphin, the Saurus crane, the Siamese crocodile (the world's "most endangered" reptile), and numerous other species of birds, turtles, fish, snails, and mussels.