What bat is the smallest mammal in the world, weighing less than a penny?

The bat commonly recognized as the world’s smallest mammal by body length is Kitti’s hog-nosed bat, also called the bumblebee bat.

Kitti’s hog-nosed bat measures only about 29–33 millimeters from head to body and weighs roughly 1.5–2 grams—lighter than a typical United States penny. It has a distinctive pig-like snout, relatively large ears, and wings adapted for hovering while it catches tiny insects near vegetation.

The species lives in limestone caves in western Thailand and southeastern Myanmar. It usually leaves its roost for brief feeding periods in the evening and again around dawn. Colonies may average about 100 bats per cave, although some caves contain far fewer or several hundred individuals.

The species was discovered in Thailand in the 1970s and named for Thai zoologist Kitti Thonglongya. A common scientific footnote is that the Etruscan shrew may be lighter by body mass, so Kitti’s bat is most precisely described as the smallest mammal by body length and the smallest bat species. Its habitat is vulnerable to disturbance and forest burning.