Summary
Highlights
Squirrels' teeth grow continuously and are orange due to tough enamel. Birds like chili peppers because they lack taste buds for capsaicin. Rhino horns are made of keratin, like hair and nails. Woodpeckers can peck 20 times per second, up to 12,000 times a day. Starfish have light-sensitive eyes at the end of each arm. Frogs absorb water through 'drinking patches' on their skin. Caterpillars have around 4,000 muscles.
Christmas tree worms hide two-thirds of their bodies in calcium carbonate tubes. Narwhals' tusks are actually incredibly sensitive teeth. Anteaters lack teeth but use a long tongue to eat 35,000 termites and ants daily. Fleas can jump over 200 times their body length. Red-eyed tree frog eggs can hatch early if threatened. Small animals often perceive time in slow motion. Koala fingerprints are so similar to humans they can be confused at crime scenes.
Hippo 'sweat' is a pink, oily fluid that moisturizes, protects, and acts as an antibiotic. Polar bears have black skin and hollow, translucent fur, even on their paws for grip and warmth. Tarantulas can live over two years without food. Platypuses close their eyes, ears, and nostrils when swimming. Emus can't walk backward despite their strong legs.
Crocodiles have tongues attached to the roof of their mouths, protecting their airways underwater. Many aquatic animals, like snakes and dolphins, can drown if submerged too long. Hummingbirds are the only birds that can fly backward, beating their wings 80 times per second. Elephant shrews are more closely related to elephants than shrews and use their trunk-like noses to find insects. Cats cannot taste sweet things.
Flamingos eat with their heads upside down due to their unique bill structure. Tiger skin is as striped as their fur. Toucans sleep in tight balls, turning their heads to rest their beak on their back. Ostriches have eyes larger than their brains, the size of billiard balls. All clownfish are born male but can become female irreversibly. Seahorses mate for life and travel holding tails.
Termites never sleep and can eat 24/7. Sloths take two weeks to digest food. Dogs' nose prints are unique, like human fingerprints. Owls have immobile eye tubes instead of eyeballs. Penguins have excellent hearing despite lacking external ears. Jellyfish are 98% water and can evaporate after washing ashore. Alligators defer to manatees in underwater traffic jams.
Grizzly bears have bites strong enough to crush a bowling ball. Giant pandas sleep wherever they are and their newborn cubs are tiny. Red hand fish 'walk' on evolved fins. Cats primarily meow at humans for attention, not each other. Sloths can't shiver, and their metabolism shuts down in extreme temperatures.
Immortal jellyfish can revert to a younger state. Chickens and ostriches are the closest living relatives of T-Rex. Moray eels have a second set of extendable jaws for catching prey. Some snails have hairy shells to stick better to wet surfaces. Humpback whales use 'bubble net' tactics to hunt. Snow leopards cannot roar but can meow, growl, hiss, and purr. Sea otters hold hands or entangle in seaweed while napping to avoid drifting.
Lionesses do up to 90% of the hunting, while males protect the territory. Cats have 32 muscles in each outer ear for ear movement. Some shark species glow in the dark, visible only to other sharks. Humans have 8,000 taste buds, dogs have 1,500. Blue jays imitate hawk coughs to scare other birds away. Slow lorises are the only venomous primates, secreting toxins from their inner arm. Wildebeest use a zigzag pattern to escape predators.
Bottlenose dolphins have individual names in the form of specific whistles. Giraffes have long, black tongues, possibly to protect them from sunburn.