Bats are mammals of the order Chiroptera (/kaɪˈrɒptərə/; from the Ancient Greek: χείρ – cheir, "hand" and Ancient Greek: πτερόν – pteron, "wing”) whose forelimbs form webbed wings, making them the only mammals naturally capable of true and sustained flight. 


Gould’s Long-eared bat common in Eastern Australia. image: R.Conan-Davies

By contrast, other mammals said to fly, such as flying squirrels, gliding possums, and colugos, can only glide for short distances. 

Bats are less efficient at flying than birds, but are more manoeuvrable, using their very long spread-out digits which are covered with a thin membrane or patagium.

Red indicates Chiroptera, blue Rodenita

Bats are the second largest order of mammals (after the rodents), representing about 20% of all classified mammal species worldwide, with about 1,240 bat species divided into two suborders:

  •  the less specialised and largely fruit-eating megabats, including flying foxes, and 
  • the highly specialized and echolocating microbats. 

About 70% of bat species are insectivores. Most of the rest are frugivores, or fruit eaters. A few species feed from animals other than insects, with the vampire bats being hematophagous, or feeding on blood.

Bats are important pollinators and seed distributors

Bats are present throughout most of the world, with the exception of extremely cold regions. They perform the vital ecological roles of pollinating flowers and dispersing fruit seeds; many tropical plant species depend entirely on bats for the distribution of their seeds. Bats are economically important, as they consume insect pests, reducing the need for pesticides. 

Sizes of bats vary a lot

The smallest bat, and arguably the smallest extant mammal, is Kitti's hog-nosed bat, measuring 29–34 mm  in length, 15 cm  across the wings and 2–2.6 g  in mass. The largest bats are a few species of Pteropus (fruit bats or flying foxes) and the giant golden-crowned flying fox, Acerodon jubatus, with a weight up to 1.6 kg and wingspan up to 1.7 m.

How bats roost

Bats are adapted to roosting, hanging upside down from their feet. The femurs are attached to the hips in such a way that it allows them to bend outward and upward in flight. The ankle joint can flex so as to allow the tailing edge of the wings to bend downwards. However, this design not permit many other movements, other than hanging or clambering up trees.


Tent-making bats roosting together(Uroderma bilobatum) in Costa Rica. image: Charlesjsharp /wikipedia

 Most megabats roost with the head tucked towards the belly, whereas most microbats roost with the neck curled towards the back. This difference is reflected in the structure of the cervical vertebrae in the two groups, which are clearly distinct. 

Tendons allow bats to lock their feet closed when hanging from a roost. Muscular power is needed to let go, but not to grasp a perch or when holding on.

Bat wings

Bat wings are much thinner and consist of more bones than the wings of birds, allowing bats to maneuver more accurately than the latter, and fly with more lift and less drag.


Wing membranes (patagia) of Townsend's big-eared bat, Corynorhinus townsendii. image:pubic domain wikipedia

The patagium is the wing's skin membrane. The patagium is stretched between the arm and hand bones, down the lateral side of the body and down to the hind limbs.

Nectar and pollen eating bats are able to hover, similarly to hummingbirds. They can produce vortex lift with their sharp leading edges and change their wing shapes and curvatures to stabilise their lift.

Bats partly ‘breath’ through their wings

Due to this extremely thin membranous tissue, a bat's wing can significantly contribute to the organism's total gas exchange efficiency.  Because of the high energy demand of flight, the bat's body meets those demands by exchanging gas through the patagium of the wing.


 24-31 October

Source adapted from: Bat. (2017, October 21). In Wikipedia, The Free Encyclopedia. Retrieved 06:40, October 26, 2017, from