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.

A sea pen may look like an underwater quill, but it's actually a colony of individual polyps — one polyp becomes the stalk of the sea pen and the bulb that attaches it to the sea floor, while the rest form feathery branches. Some sea pens have only a few polyps, while others have as many as 35,000.

The large-billed tern uses its disproportionately long and thick beak to catch fish — either by plunge-diving into the water or skimming the surface with its beak as it flies. It has a commensal relationship with the tucuxi river dolphin, which often flushes fish towards the surface while hunting.

A female Pacific blackdragon is ~60 cm (2 ft) long and uses a bioluminescent lure on her chin to attract prey. Her skin is 'ultra-black', among the darkest in nature, and her teeth are anti-reflective, so as not to reflect light from her lure and alert her prey. The male is only ~8 cm (3 in) long.

The common reed frog exhibits extreme variation in colour patterns — with some 50 recognised subspecies. Additionally, this frog changes the colour of its skin according to weather and temperature, turning pure white in the heat of the dry season.

Endemic to Fiji, the golden fruit dove exhibits remarkable sexual dimorphism — the female is forest green while the male is a brilliant golden yellow. This dove lives in the canopy and is more often heard than seen, producing dog-like barking, low growling, and snoring noises.

Endemic to Japan, the Japanese badger — like other badgers — lives in underground dens called "setts". However, the Japanese badger is known to be more solitary, with even mated pairs often living in separate setts. It is currently unknown why this is the case.

The palm-nut vulture is unusual among vultures, in that about 70% of its diet is vegetarian — mostly consisting of palm nut fruits. It was once called the "vulturine fish eagle”, because of its eagle-like appearance and the way in which it hunts; swooping to the water's surface to grab fish.

The giant otter shrew is named for its resemblance to both an otter and a shrew, despite not actually being either. It hunts nocturnally in forest pools and streams, swimming with a laterally flattened tail, like that of a fish or crocodile — an unusual swimming method among mammals.

A remora uses the sucking disk on top of its head to attach itself to larger marine animals like sharks, rays, and sea turtles — where it can stay for 3 months. The host provides the remora with protection, food, and a fast flow of water over its gills, which the remora needs in order to survive.

A silkworm wraps itself in a fluid substance from its silk glands that hardens to become a cocoon — this cocoon can be unravelled to a single strand reaching lengths of 1.5 km (1 mile). Inside, it "digests" its own larval body (called histolysis) before building up the body of a silkworm moth.