Forget branching antlers: the water deer sports inch-long retractable canine fangs, barks like a dog, bounds like a rabbit, and swims for miles across open rivers. This patchwork creature, scientifically named "defenseless" despite its three-inch tusks, lives a fractured existence. It is critically endangered in its native China yet has exploded to 700,000 individuals in South Korea, where it is now classified as harmful wildlife.

This episode explores the biology and improbable global journey of one of nature's strangest survivors. We unpack the muscle-controlled switchblade fangs, the ritualized stabbing combat, the bizarre vocalizations, and the highest reproductive capacity of any deer. Then we trace the population extremes across China, Korea, England, France, and Russia, including a Victorian-era escapee colony in Britain that now hol ...