A blue whale’s tongue is massive and can weigh as much as 8,000 lbs (3,600 kg).

All oysters are born male but most change their gender to female after about a year and can switch back at will. An oyster is therefore able to produce both eggs and sperms.

Considered to be the loudest land animals, howler monkeys create loud, guttural sounds to defend their turf, that can travel up to 3 miles (4.8 km).

Polar bears have clear fur covering a layer of black skin which helps them absorb the sun's rays better. The rays get trapped in the fur and cause luminescence which makes it look white.

A cheetah can accelerate from 0 to 60 mph (95 km/h) in just 3 seconds. That’s faster than a Ferrari Enzo.

Moths have a mid-gut where the digestion occurs and a sack-like structure called the crop, where they store food. They live only for a week to mate and die after laying eggs.

When a honey bee sucks up nectar from a flower though its proboscis, some of it goes into the main stomach to be used as food for energy. The remaining goes into a special stomach to be processed into honey.

Due to their immense size, elephants produce a lot of body heat. Thankfully, much of it radiates out through veins in their large floppy ears. An elephant can lose as much as 48 degrees Fahrenheit (9 degrees Celsius) through its massive ears.

Don't go by their cute appearances – poison dart frogs are some of the deadliest animals on earth. A single poison dart frog possesses enough venom to kill 10 adult men. Sometimes, animals die simply by touching a spot where a dart frog had just been.

The smallest bird in the world, the hummingbird is immensely fast and swift and can fly backward, upside down and even sideways. However, their legs are too weak and tiny to support walking. The most they can manage is to shuffle sideways.

Male gentoo penguins look for the smoothest, shiniest pebble to present to females of their choice. If the female accepts, she takes the pebble and places it in her nest, accepting the male as her mate.

Cows have been found to produce more milk while listening to slow music. The calming effect of music is known to stimulate milk production, according to research.

Ostriches live in large groups and the males produce a deep grunt, commonly mistaken as a "roar," as a warning call to defend their territory. This behavioral sound comes naturally to them.

This is why dogs leave wet footprints behind when their body temperature rises. However, this is just a minor method of releasing body heat as dogs rely more on excessive panting to cool down.

Spider silk, though thinner than human hair, is shockingly stronger than steel and as strong as nylon of the same width. It can also stretch up to 30 percent of its original length without breaking. A 2-inch-thick rope made of a spider thread can even stop a Boeing 747, research claims.

Like most insects, dragonflies have six legs but still can't walk. These winged creatures use their legs for grabbing and perching, but they don't support walking.

This is their way of coping with three months of constant summer sunlight followed by another three months of winter darkness. During summers, reindeer eyes reflect most of the light through the retina and thus appear golden in color. In winters, enhanced night vision kicks in and a layer of tissue appears behind the retina making it look blue.

The electric eel can deliver enough electricity to knock down a fully grown horse. One of the most formidable predators in the animal kingdom, an electric eel's body has specialized cells that can emit 600 volts of current.

Cockroaches can survive decapitation because they breathe through openings called spiracles on their body, which are not controlled by their brain. A headless cockroach will die after about a week out of thirst and hunger.

A turtle's gender is not determined by chromosomes but the ambient temperature of the eggs. This has become a matter of concern in light of global warming with a threat of an all-female population and extinction.

A giraffe's neck has seven vertebrae just like humans. The difference, however, is in the size of the bones. Each vertebra in a giraffe can measure up to 11 inches (28 cm).

Butterflies do not have a mouth or taste buds to taste food. Sensors located at the back of their legs help them identify whether what they're stepping on is palatable.

African wild dogs are known for being particularly nice to the young, old and injured of their pack. They bring back food for the old and injured, nourish them and take care of their wounds by licking them.

Alpacas are gentle and docile animals and enjoy each other's company. When kept alone, they become sick and eventually die. Therefore, it is advised that alpacas must always be bought in pairs if not an entire herd.

Otters are known to float while eating or sleeping. They hold each other’s hands while sleeping so they don’t drift apart and separate from the herd.

Flying snakes can reach up to 330 feet (100 meters) in air while gliding. They use the speed while free falling and contort their bodies to generate lift.

Relative to their body size, chameleons have the longest tongues in the animal kingdom. The reptile keeps its tongue rolled up like a rope inside the mouth and unfurls it accelerating up to a speed of 13 mph (20 km/h) to attack its victim.

A bull moose sheds its antlers every winter so it does not have to carry the weight. It grows it back again each summer to attract mates.

Dog nose prints are just as unique as human finger prints and can be used to identify them.

Unlike fish, shrimp do not have fins to swim. To move around in water, it pulls its abdomen toward its body and creates a motion that makes it shoot through water. Because of its body configuration this movement is always backward.

During breeding season, a lioness can mate up to 100 times a day with multiple partners with an average interval of 17 minutes. A male, on the other hand, mates about 20 to 40 times a day.

Considered the fastest fish in the ocean, its speed is as much as that of a running cheetah, the fastest land animal. This speed is facilitated by its hydrodynamic shape, a giant dorsal fin and a long, pointy nose.

Sea horses are the only animals in the entire world whose male members carry their young rather than the females. While mating, the female leaves the eggs in the small pouch of the male, thereby making it pregnant. This leaves the female free to make more eggs and reproduce at a faster rate.

These tiny insects use the toes of their legs as catapults, jumping with immense force.

To do this, they cocoon themselves in a cloak of air bubbles that come from their feathers, swim swiftly to the water surface and burst out to land at their destination.

Rats are ticklish in their nape area and emit long, ultrasonic sounds when tickled there. These sounds can be heard by the human ear using special equipment.

A leech has three separate jaws, each with 100 tiny, razor-sharp teeth to bite through skin and suck blood.

Butterflies have compound eyes which means that each eye is made up of thousands of eyelets that act as individual light receptors with their own microscopic lens to produce a mosaic view.

Gorillas can catch cold and are affected by other human viruses as well. They are also known to suffer from illnesses like pneumonia and other respiratory disorders, just like humans.

Their elongated eyeball shape inhibits them from moving or rolling them. But owls have binocular vision like most other animals.

While nobody knows the exact number of ants in the world, estimates suggest there are in excess of one million ants to every human on the planet.

A starfish has five eyes, one on each of its legs. They're not like traditional eyes, however – more like black or red spots that can detect light and darkness.

Goats have rectangular pupils that help them avoid predators. Rectangular pupils allow extensive peripheral vision that helps them see the entire terrain and plan their escape.

All 47 teeth have cutting edges that help a mosquito to break through the skin of other animals to allow the proboscis tube to penetrate.

To survive through winters, tree frogs "freeze" and come back to life as soon as spring arrives. Commonly known as estivation, this technique includes finding a crevice and building a cocoon around their body, leaving only the nostrils exposed.

Like humans, horses use facial expressions to communicate with each other. They move the muscles around the nostrils, lips and eyes to create different expressions that help them, in a way, talk to each other. As of now, 17 different horse expressions have been identified.

On an average, a bald eagle's nest is roughly eight feet (2 meters) wide and 13 feet (3.9 meters) deep and can weigh up to a ton. In fact, a bald eagle's nest found in 1925 weighed almost two tons.

Hippos secrete a reddish oily fluid – sometimes called pink sweat – that contains substances which act as water repellent, sunblock, skin moisturizer as well as an antibiotic!

Dolphins have developed a unique sleep pattern that allows them to sleep with one eye open and one hemisphere of their brain still active. The other half of the brain keeps a vigil of the surrounding environment and breathing functions.