There are about 1,100 bat species worldwide, which represent about twenty percent of all classified mammal species. About seventy percent of bats are insectivores. Most of the rest are frugivores, or fruit eaters. A few species feed from animals other than insects. Bats are present throughout most of the world and perform vital ecological roles such as pollinating flowers and dispersing fruit seeds. Many tropical plants depend entirely on bats for the distribution of their seeds.
Bats range in size from Kitti's Hog-nosed Bat measuring 29–33 mm (1.14–1.30 in) in length and 2 g (0.07 oz) in mass, to the Giant Golden-crowned Flying-fox, which has a wing span of 1.5 m (4 ft 11 in) and weighs approximately 1.2 kg (3 lb).