World's Weirdest Season 4

In the battle for survival, brawn isn't always enough to keep you alive. Animals have learned to use their brains to solve the eternal problems of getting food, finding shelter and protecting family. From whales that create bubble walls to catch their fish, to dolphins that work with humans to catch their dinner, to prairie dogs that speak their own language. These brainiacs will have you cowering behind the sofa as they flaunt their intelligence and apply logic to fulfill instinctual needs

Billions of years of evolution and more than 1 million species of animal have created very weird world and some very bizarre body parts. From sex-crazed slugs to Kung Fu crustaceans, from blood-firing lizards to zombie snails, we journey from the ocean depths to deserts and tropical rainforests to reveal that for some creatures, the truth really is stranger than fiction. We showcase some of the strangest, most shocking animal appendages on the planet, and uncover their evolutionary advantages.

On the frozen wastes of Antarctica, a mother-to-be Adlie penguin sells her body for stones. In deepest, darkest Africa, chimpanzees trade meat for sex. In Canada, a post-hibernation gathering of garter snakes becomes a frenzied orgy. A redback spider eats her partner alive while they're still mating. Are these animals behaving badly? Or is the drive to reproduce so fundamental in the animal kingdom, that "anything goes"? Meet the world's weirdest friends with benefits.

If it creeps, crawls, buzzes or sheds its exoskeleton, there's a chance it could cure an illness that's stumping modern medicine. Parasitic worms, flesh-eating maggots, blood-sucking leeches, and skin-nibbling fish -- man runs from these creatures and often tries to eradicate them. But scientists and MDs are finding out just how much we need these creepy-crawlers to stay healthy. We explore the healing properties of the animals many think are disgusting, but sometimes turn out to be lifesavers.

Nat Geo WILD explores nature as it gets rolling drunk and spaces out, and delves into the importance, or lack thereof, of intoxication in the animal kingdom. Meet monkeys that binge drink and throw frat parties, elephants that go on drunken rampages through villages and lemurs that get high off millipedes. And when a jaguar's hunting skills may have been enhanced by chewing on psychedelics, scientists question whether or not there are evolutionary benefits to psychoactive compounds.

The early days for any species are precarious. Nat Geo WILD reveals the World's Weirdest methods employed by mothers and their offspring to sidestep and outwit their predators. Stealth, cunning, disguise, poison -- no trick is too low down or too dirty for parents who want to make sure their babies get a head start over their hungry foes. And marvel in the wealth of evolutionary adaptations that give these newborns a chance to flourish. It's life but not as you might know it.

Nat Geo WILD goes behind closed barn doors to reveal some of the most bizarre farms, farming methods and farmers on the planet. From the unusual to the downright dangerous, it's a rarely seen side of farming. Visit a farm in Utah that is home to spider goats, the world's first mammal/arachnid hybrids. In Thailand, one farmer is using elephants to produce coffee. And visit a leech farm in Wales where the bloodsucking creatures are used for medical science.

High in the frozen Japanese Alps, female snow monkeys engage in same-gender sex. Across the African savannah, "Lion Kings" enjoy intimate male friendships. A pretty seahorse is not just a dad, he's a pregnant dad. And a Mexican whiptail lizard is about to experience a virgin birth. In nature, gender is as flexible as life itself. Meet the World's Weirdest Swingers.

Mass animal deaths are occurring across the globe. Should we all be freaking out about the end of the world? Or are there logical explanations? World's Weirdest: Animal Apocalypse features the puzzling cases of animals behaving bizarrely: millions of mice overtaking farms and buildings, hundreds of whales beaching on a shore, thousands of blackbirds suddenly raining from the sky and frogs spontaneously exploding.