Red River giant softshell turtle

The Red River giant softshell turtle (Rafetus swinhoei) may be the rarest and most threatened of all turtles, in addition to one of the largest – only four individuals are known remaining alive in the world.

Two long-term captive animals in China were brought together three years ago and have produced eggs, but these eggs failed to develop. One lone animal confined in Hoan Kiem lake in downtown Hanoi is revered as symbol of Viet Nam’s independence.

And the last animal remaining in the wild became the reluctant subject of a hostage drama when his home reservoir burst its dam in November 2008, and was caught downriver by a fisherman; the turtle was handed over to conservationists only after protracted negotiations, and was then released back into its native wetland.

IN PHOTOS: View a photo gallery of endangered turtles.