Steller's sea-eagle is a rare raptor from the rocky coasts and rivers of northeastern Siberia — flying southwards to Hokkaido, Japan, in winter. It's the world's heaviest eagle and a particularly aggressive species, known to frequently steal fish caught by other eagles.

Marine hatchetfish are creatures of the deep. They have rows of light-producing organs along their bellies which shine a pale blue — matching the light from above and making the hatchetfish invisible to predators below. This fish's name comes from its body shape, which resembles the head of a hatchet.

Lidth's jay is only found on a few of the Ryukyu Islands in southwestern Japan. Its existence has been threatened by the introduction of mongooses and an increased crow presence on these islands. As of a 2016 survey, fewer than 3,900 mature jays are estimated to remain.

The Japanese pygmy seahorse is the size of a grain of rice — about 1.6 cm long (0.6 in) — among the smallest seahorses in the world. It wasn't formally named until 2018, whereupon it received the specific title of "japapigu" or "Japan pig", because locals think it resembles a baby pig.

To make his presence known, a male copper pheasant will drum loudly with his wings — creating a thunderous "phrrrrp" sound — and show off his tail feathers, which can grow to be 125 cm (4.1 ft) long. The males also fight for a female's favour; jumping and kicking each other to decide a victor.

For over 1,300 years, the Japanese cormorant has been part of a traditional fishing method known as ukai. A dozen cormorants swim alongside a wooden boat, each held by a leash around the neck. The cormorants catch and swallow fish into their throat pouches and, afterwards, the fishermen make them "cough it up".

A male blood pheasant has splatters of "bloody" feathers across his face, breast, and tail. This species lives in the Himalayan Mountains, feeding mostly on mosses and moving with the snowline between elevations of 3,200–4,700 metres (10,500–15,400 ft). It's adapted to resist both hypoxia and high UV radiation.

The pumpkin toadlet is one of the smallest frogs in the world — only some 18 mm (0.7 in) long. Because of its minuscule size, the organs in its ears that are responsible for balance cease to work mid-jump. As such, it cartwheels rigidly through the air before making a clumsy, floppy landing.

Skeleton shrimp are skeletally thin and often have ghostly transparent bodies. They grasp algae with their spindly rear legs, while their front legs form large "claws" used for grooming, defence, and capturing prey. Luckily, they only grow to a couple of centimetres (~1 inch) long.

The Japanese weasel's agility and lithe body allow it to pursue its prey anywhere; down tunnels, up trees, or into water. During winter, it spends its time pursuing rodents through snowy tunnels and, after catching and eating its target, it lays down to enjoy the warmth of its prey's burrow.

The torrent duck is highly adapted for hunting within the fast-flowing rivers of the Andes — it kicks with powerful webbed feet, its long claws cling to slippery rocks, and its sleek body allows it to scale waterfalls. Even chicks, soon after hatching, plunge into the dangerous currents.

The riverine rabbit is among the rarest rabbit species in the world. Considered 'critically endangered', only around 250 individuals survive in a few areas of the Karoo Desert in South Africa — where they typically live along seasonal rivers.

The Mexican mole lizard digs intricate tunnels that run below the surface of the soil. To regulate its body temperature, the mole lizard moves to tunnels at different depths — it spends cooler mornings near the surface and as the day heats up, it moves deeper and deeper below ground.

Often described as ghostly, the elusive Japanese serow lives in the wooded mountains of central and southern Japan. Typically solitary, it stands on rocky outcrops, staring down at the landscape for extended periods — likely watching for predators or rivals. It can be active both day and night.

The willie wagtail is aggressively territorial. It's known to harass much larger birds (including eagles), venomous snakes, and humans that wander too close to its nest. Before an assault, it flares its white "eyebrows", making it look especially enraged.

While the spotted owlet is nocturnal, it can sometimes be seen during the day — it will bob its head and stare intensely at anyone who bothers it. This owlet can be located by watching for the small birds that often mob it or — during dusk and dawn — by the owlet's “chirurr-chirurr-chirurr” chuckle.

The Chinese softshell turtle uses its tubelike nostrils to "snorkel" while staying submerged beneath the water. Most turtles urinate through their cloacas, but to avoid losing water, the Chinese softshell can secrete urea from its mouth — essentially peeing via its mouth.

During mating season, male red salamanders are not aggressive towards each other. In fact, they actually court one another — this likely isn't a case of mistaken sex, but an attempt to trick rival males into wasting their sperm packets (spermatophores).

The speckled mousebird hangs belly to belly with others in its flock to keep warm while sleeping. After a meal — of toxic plants, clay, dirt, and peddles — a mousebird may hang upside down, exposing the black skin of its belly to the sun in order to warm up and aid digestion.

A male Visayan warty pig can become four times larger than a female. During mating season, the male uses his tusks for combat and three pairs of warty growths on his face for defence — he also grows a 23 cm (9 in) long mane to attract females. The species is only found on two Philippine islands.