Vespertilionid Bats: Vespertilionidae

Although this group of bats is large and contains many different-looking species, they do share several characteristics. Compared to many other bats that have what might be described as bizarre noses with flaps and other fleshy decorations, the vespertilionid (ves-per-TILL-ee-on-id) bats have plain faces. They are even known as the "plain-faced bats." Some species have noses shaped like tubes, however, with nostrils at the end of the tube.

The "webbed tail," known as a patagium (pah-TAY-jee-um), is actually a membrane or a thin bit of skin that stretches between the hind legs and aids the bat in flight. In these bats, the patagium is hairless. Their ears are noticeable and sometimes quite large, and they also have tails at the middle of the patagium that can be as long as the body. All have an obvious outgrowth, called a tragus (TRAY-gus), arising from the bottom of the ear. Most of them have small eyes. Overall body length ranges from about 1.4 to 5.5 inches (3.5 to 14 centimeters) and weight from 0.01 to 1.6 ounces (2.5 to 45 grams).