Bats, members of the order Chiroptera, are placental mammals. Bats are the only mammals that can fly for sustained periods, using their own power. Bats use their wings to propel themselves through the air, like birds do.
Bats can use their wings to move up and down in the air. Some bats can hover.
There are other mammals, such as flying squirrels, that can glide through the air, but they cannot truly fly.
A bat's body has many adaptations that allow it to fly.
The wing of a bat is a modified version of a normal mammalian front limb. The hands and fingers are highly elongated, so they can support a wing membrane, which is known as a patagium. The patagium is connected to the bat's legs and back.
Chiroptera is Greek for "hand wing".
A bat's hind leg has a hip joint that is rotated at a 90 degree angle so the leg sticks out the side. This arrangement enables the leg to support the patagium when the bat is flying. However, it also gives the bat an unusual walk.
A bat has extra muscles in its chest that it uses for flight. Because of this, most of the bat's weight is concentrated in its chest.
The bones of a bat are thin and light.
Bats have short necks and short hind legs.
A bat doesn't have the power to take off in flight from the ground. It has to climb up to a high spot and then allow itself to fall before it starts to fly.
Bats are nocturnal. They roost at night and are active during the day.
A bat may roost in a cave, a crevice, a tree or even in a human structure such as a house.
When bats roost, they hang upside down by their back limbs. Most bats have tendons in their toes that lock their claws in place when the bats are hanging upside down. This allows the bats to sleep without falling from their roosts.
Bats are found almost everywhere on Earth. There are no bats near the North and South Poles. Some isolated islands do not have any bats.
The smallest mammal in the world is the bumblebee bat (Craseonycteris thonglongyai), also known as Kitti’s hog-nosed bat. It is only a little over an inch long and weighs only about 2 grams.
There are two kinds of bats alive today: echolocating bats (Microchiroptera) and flying foxes or fruit bats (Megachiroptera).