The smallest mammal in the world is the bumblebee bat, also known as Kitti's hog-nosed bat. This tiny creature weighs about 2 grams and measures around 3 centimeters in length. 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 mammal is the Etruscan shrew, which is slightly larger than the bumblebee bat. Weighing about 1.8 grams and measuring around 3.5 to 5.2 centimeters, it is known for its high metabolism and rapid movements. Both animals showcase the incredible diversity of the mammal class.