The smallest animal in the world is the bumblebee bat, also known as Kitti's hog-nosed bat. This tiny mammal weighs about 2 grams and has a wingspan of around 5.7 inches. It is found in parts of Thailand and Myanmar, living in limestone caves and feeding on small insects. Another contender for the title of smallest animal is the Paedophryne amauensis, a species of frog discovered in Papua New Guinea. This frog measures just 7.7 millimeters in length, making it the smallest known vertebrate. It lives in leaf litter and is known for its unique calls and small size.