The color varies from pale brown, russet to dark brown. They have a mostly black membrane covering their wing.
Females are larger than males.
Other nocturnal animals have big eyes to use the remaining light effectively. Bats generate ultrasound in their larynx and then emit it through the mouth or nostrils. Bats have big ears to collect the sounds they send out. The echos are transferred to the brain where they are analyzed and the brain makes a picture of the surrounding. Bats use echolocation because it is a short wavelength.