Darwin's Amazing Animals

Divers descend into the nighttime morass of a hundred thousand small slimy creatures extending in all directions. It's a squid run, a rarely seen soiree now at great risk due to climate change. The Darwin team has combed the depths searching for clues to explain this massive gathering. The result? Incredible footage of a range of mating behaviors, from aggressive multi-armed battles and intimate pairings to a mother's delicate depositing of egg casings in a blossom-like pattern on the sea floor.

Why do most iguanas just ... sit there? 96% of the day, in fact! Well, they're herbivores, which is very rare in the lizard world. Digestion can only occur when that cold-blooded body heats up to 40 degrees Celsius. When they do move, however, things get interesting. From escaping predators to mating behaviors, the iguana's true intelligence is on full display. Ask any pet owner and you'll hear some lively tales of the costly upkeep and close personal bond the iguana forms with its human host.

More than a million sooty terns spend the breeding season in the Seychelles, a bird paradise safe from natural predators. Yet their hungry young must contend with a host of survival challenges from the air, land and sea. Meals depend on food-bearing parents avoiding the prying eyes and beaks of jealous frigatebirds. The environmental scourge of microplastics is also proving fatal to these vulnerable chicks. And fledglings face an entirely different threat that rises unseen from the ocean depths.

The Ezo mountain hare in Japan's far north relies on a range of ninja-like survival strategies: white winter fur for camouflage in the snow; a hare-raising speed of 80 kilometers per hour; and the ability to magically disappear! Don't blink ... or you just might miss it! However, all that is thrown to the wind during the warm months of the mating season. With their alert level down and romance on their minds, their biggest nemesis, the Ezo red fox, enjoys its best chance to capture some prey.

The ladybug faces many challenges in the microworld right at our feet. Most predators stay clear however, having experienced the foul smelling and tasting yellow liquid the beetle secretes. That smooth slippery dome on top also provides vital protection. But this adorable creature is powerless against a type of parasitic wasp. The nasty nemesis plants an egg in the ladybug's abdomen, which steadily consumes its host's internal tissues. It then "zombifies" the ladybug into its own bodyguard!

Hidden in the tree-covered mountains a few hours from Tokyo lies a simple puddle with a big secret. It never dries up, and attracts wildlife including green pigeons who gulp down its mysterious waters. The puddle is fed by a natural spring full of minerals including sodium, which the birds crave as a supplement to their fruit-rich diet. But this craving can be their undoing, as keener eyes survey the scene from above. The mountain hawk-eagle can swoop down in an instant, catching prey unawares.

Over 100 years ago, sea otters were hunted to the brink of extinction along Japan's coastline. But these adorably cute mammals are back and getting a welcome return in the northern prefecture of Hokkaido. Crowds line the cliffs of a remote cape to view 10 such creatures as they eat, care for their young and float on the water's surface as they sleep. But challenges remain. As their population increases, so will the effect on the area's marine resources, including clams, sea urchins and crabs.

The sharks are circling ... but those jaws aren't meant to incite panic! The Darwin crew joins a survey team as it tries to unlock the secrets of the docile and endangered sand tiger shark in the wild. The group has chosen Japan's Ogasawara Islands, a World Natural Heritage site, as its research base. Tracking soon leads to a range of locations, revealing never-before-seen behaviors. The discovery of a pair of pregnant sharks and their rather rambunctious fetuses leaves the researchers stunned.

A steady stream of tourists come to Yakushima Island each year to gaze up in awe at Japan's most famous tree. The Jomonsugi cedar exceeds 16 meters in circumference and is thought to be more than 2,000 years old. Is it the country's largest? And what lies up in the treetops hidden from view? The Darwin crew joined a special research team traversing the dense undergrowth in their four-year quest to locate other massive cedars and document the incredible ecosystem thriving in the tallest branches.

An autumn evening stroll often brings with it a cacophony of cricket cries. Males' love songs fill the air, destined for faraway maidens. How do they produce such amazing sounds? And what are the exacting standards set by their love interests? Singing insects have captured hearts and imaginations for centuries, even making appearances in two of Japan's most celebrated classical novels written over 1,000 years ago. We invite you to venture out and enjoy some of nature's nightly outdoor concerts.

Next time you pass by a mushroom, consider this: underneath that cap and stalk lies a network of thread-like filaments that could spread out up to a radius of one kilometer! Welcome to the "Marvelous Mystery Tour!" There are between 5,000 and 10,000 species of mushroom just in Japan. Yet only about 3,000 have names. And they come in all shapes, sizes, colors ... and odors! Mushrooms are without a doubt integral to forest ecology. Join us as we enter a whole new world just by lowering our gaze!

Energetic African golden wolf pups get attacked by their parents while docile pups get pampered. What gives? It's all part of an incredible educational system designed for the savanna. The young are taught to protect themselves while scavenging and seeking out small rodents in the tall grass. Yet all this time no pup is left behind. Those showing initiative are soon encouraged to leave and become independent. The timid variety may stay with the parents and help raise the next generation.