bat

Any mammal of the order Chiroptera, related to the Insectivora (hedgehogs and shrews), but differing from them in being able to fly. Bats are the only true flying mammals. Their forelimbs are developed as wings capable of rapid and sustained flight. There are two main groups of bats: megabats, which eat fruit, and microbats, which mainly eat insects. Bats are nocturnal, and those native to temperate countries hibernate in winter. There are about 977 species forming the order Chiroptera, making this the second-largest mammalian order; bats make up nearly one-quarter of the world's mammals. Although bats are widely distributed, populations have declined alarmingly and many species are now endangered.

Megabats
The Megachiroptera live in the tropical regions of the Old World, Australia, and the Pacific, and feed on fruit, nectar, and pollen. The hind feet have five toes with sharp hooked claws from which the animal suspends, head downwards, when resting. There are 162 species of Megachiroptera. Relatively large, weighing up to 900 g/2 lb and with a wingspan as great as 1.5 m/5 ft, they have large eyes and a long face, earning them the name ‘flying fox’. Most navigate by sight.

Microbats
Most bats are Microchiroptera: small and insect-eating. Some eat fish as well as insects; others consume small rodents, frogs, lizards, or birds; a few, vampire bats, feed on the blood of mammals. A single bat may eat 3,000 insects in one night. There are about 750 species. They roost in caves, crevices, and hollow trees. The bumblebee bat, inhabiting Southeast Asian rainforests, is the smallest mammal in the world. A new species of bat, Rhinolophus convexus, was discovered in Malaysia, at an altitude of 1,600 m in the Cameron Highlands, in 1997. It is related to the tropical horsehoe bats. In December 2001, a new bat species was discovered in Greece. It is a whiskered bat, species Myotis, and is the smallest of the species.

Many microbats have poor sight and orientation and hunt their prey principally by echolocation. They have relatively large ears and many have nose-leaves, fleshy appendages around the nose and mouth, that probably help in sending or receiving the signals, which are squeaks pitched so high as to be inaudible to the human ear.