The hooded pitohui is one of the few known toxic birds. Like poison dart frogs, it builds up toxins in its body — likely from beetles that it eats — storing them most potently in its feathers which can cause an itching, burning, and numbing sensation when touched.

The olm is a blind salamander found only in the caves of the Dinaric Alps. Like the axolotl, it never metamorphoses, and its maximum lifespan has been estimated at ~102 years. Olms would occasionally wash out of caves during floods and were once believed to be baby dragons in Slovenia.

The Okinawa rail is Japan's only flightless bird — found exclusively on the island of Okinawa. Before nightfall, it uses its powerful clawed feet to climb trees, where it sleeps to avoid nocturnal-hunting pit vipers. In the morning, it drops back down in a graceless fluttering of wings.

The island canary — native to the Canary Islands, Madeira, and the Azores — is the wild ancestor of the domestic canary. It was bred to be garishly coloured, to have different haircuts and postures, and to imitate the songs of other birds or the sound of babbling water. Later, it was used to detect dangerous gases in coal mines.

The white-rumped vulture was once India’s most common vulture — and perhaps the most numerous large bird of prey in the world. But between the mid-1990s and 2006, its population plummeted by 99.9%, and it’s now considered critically endangered.

The desmans are the odd duo out in the mole family. Both are semi-aquatic: the Russian desman lives in slow-moving waters, while the Pyrenean prefers fast-moving mountain streams. Desmans were more numerous once, but today these are the last two species left.

The Kauaʻi cave wolf spider has adapted to the lightless caverns of southern Kauaʻi by losing its eyes entirely. It creeps slowly — consuming ~40% as much oxygen as surface-dwelling wolf spiders — pursuing its primary prey: the Kauaʻi cave amphipod, a blind crustacean endemic to the same caves.

The raccoon dog isn’t a raccoon at all — it’s a canid, more closely related to foxes. It’s the only member of the dog family that hibernates and one of the few to use communal latrines, where it leaves behind smelly “messages” about its diet, health, and breeding status for other raccoon dogs to sniff out.

The white-tipped sicklebill uses its extremely decurved bill to reach inside sharply curved flowers, allowing it to drink nectar other nectarivores cannot reach. It is also a ‘trapliner’ — repeating the same foraging circuits, visiting favourite flowers along its particular route.

The immortal jellyfish is so-called because it can revert to a previous stage in its life cycle due to stress or injury. However, this isn't immortality as we typically think of it: the jelly turns back into a stationary polyp that spawns several genetically identical medusae.

The Kangaroo Island dunnart lives only on Kangaroo Island, off South Australia. In 2019–2020, catastrophic bushfires swept across the island, burning over 90% of the dunnart’s habitat. The species was feared extinct, but a few were found to have survived — perhaps just 50–100 individuals.

The eastern and western meadowlarks look nearly identical, behave in the same way, and share similar habitats — even overlapping in range in the central plains of North America — yet they are separate species that rarely interbreed. What keeps them apart are the different songs they sing.

The male Darwin’s frog “swallows” his offspring — nudging the eggs into his vocal sac — where they soon hatch into tadpoles. He carries them for 50 to 70 days, during which they develop entirely within the sac, before spewing out fully formed froglets.

The pygmy hog is the smallest pig species in the world — standing just 25 centimetres (9.8 in) at the shoulder. It is also one of the rarest. Once widespread across the southern foothills of the Himalayas, fewer than 250 mature individuals now survive, confined to a small patch of grassland in Assam, India. 

Each spring, thousands of firefly squid gather in Japan’s Toyama Bay and light up the water with their neon-blue bioluminescence. After laying and fertilising their eggs, they die. A year later, their offspring will return to do the same.

The Asian koel is a brood parasite that lays its eggs in the nests of other birds. The species is also sexually dimorphic: males are dark-feathered goths, while females are boldly streaked in brown and white.

The pig-nosed turtle is the sole surviving species in its family. It lives in the rivers of northern Australia and southern New Guinea, using its pig-like nose to "snorkel" without exposing the rest of its body.

The saola — often called the "Asian unicorn" — is endemic to the Annamite Mountains of Laos and Vietnam. Discovered by science in 1992, it has never been directly observed alive by researchers in the wild and may number fewer than 100 individuals.

The capuchinbird is named for its resemblance to Capuchin monks, with the brown plumage around its bald head looking like the monks’ hooded robes.

Rainbow lorikeets travel in nomadic flocks, following the flowering of trees — using their brush-tipped tongues to feed on nectar and pollen. At night, they roost communally, perching close together and occasionally hanging upside down or lying on their backs, feet in the air.