Halloween may be the bats' favorite day, if they were aware of human festivities. On this day, bats have the spotlight as they appear on posters, costumes and house decorations. But are you sure you know this animal you put up on your apartment door? Let's check out some fun facts: The bat is more than "black, scary rats with wings!" 

It is estimated that there are 900 to over 1,200 species of bats in the world, making up one-fifth of Earth's total mammalian species. They love to stay in large groups, too. You may find millions of bats in one group. So why is our world not full of bats? Maybe because they only have one baby per year. 

The smallest bat (also one of the smallest mammals in the world) measures only about three centimeters in length, weighing two grams, with a 15-centimeter wingspan. The biggest bat, however, may have a wingspan of 170 centimeters. 

False! 

Most small bats do have poor eyesight, and rely on echo location to catch prey, and feed on insects. But most big bats have very accurate vision, and rely on their sight instead of echo location, and mainly eat fruits and nectar. No matter big or small, no bat is blind. 

A few species of bats in Central and South America feed on nothing but blood. Some feed on large mammals, some feed on birds. Their saliva can keep the blood from clogging. Instead of "sucking" blood, the vampire bat licks blood from wounds, much like a dog or a cat drinking water. 

As the only mammal who can fly rather than glide, the bat is quite a good aviator. A species of bat in mexico can achieve a speed of 160 km/h. To ensure sufficient blood supply, the bat has a large heart: Three times larger than a terrestrial mammal of the same size. But, limited by body structure, the bat cannot do long distance travelling nor maintain high altitude flight.

Everyone knows the bat hangs upside down when sleeping. Doesn't it get tired or dizzy? Thanks to its amazing muscle structure, the bat can lock its feet closed when hanging. It needs muscle power to let go, not to hold on. The bat's light body weight also ensures that it does not suffer from blood rushing to its head. 

Many bats hibernate during winter. Males of these species mate with the females in hibernation (and they do not help take care of the babies). Luckily, the females use a variety of strategies to control the timing of pregnancy and labor. Sometimes the female stores sperm and chooses to fertilize its egg a few months later. So do not worry that bat babies will be born during their mothers' hibernation period. 

Because of their high metabolism, bats have to eat huge amounts of food. Insect-eating bats may eat over 120 percent of their body weight, while fruit-eating bats may eat over twice their weight. A single brown bat can eat 1,200 mosquito-sized insects in an hour. The 20 million Mexican free-tailed bats living in Bracken Cave of Texas, U.S, eat about 200 tons of insects each night. 

He was not even American, but was worshiped by the Aztecs. From roughly the 13th to the 16th century, the Aztec civilization of central Mexico worshiped Mictlantecuhtli, the principal god of the dead. This deity was depicted to have a bat face. Some bat-god sculptures from Mexico can even be dated back to 300-500 AD. 

The bat is usually connected with death, evil, darkness and bad omen. However, the animal is a symbol of happiness in China, because the word "bat" has the same pronunciation of "blessing" ("fu") in Chinese. Hence, the bat often appeared in ancient Chinese paintings and decorations. 

(Cover image via VCG, designed by CGTN's Qu Bo)

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