What is the world's smallest living mammal?

The Etruscan shrew has a body length of about 4 cm (1.6 in) excluding the tail. It is characterized by very rapid movements and a fast metabolism, eating about 1.5–2 times its own body weight per day. It feeds on various small vertebrates and invertebrates, mostly insects, and can hunt individuals of the same size as itself. These shrews prefer warm and damp climates and are widely distributed in the belt between 10° and 30°N latitude stretching from Europe and North Africa up to Malaysia. They are also found in the Maltese islands, situated in the middle of the Mediterranean Sea. Although widespread and not threatened overall, they are generally uncommon and are endangered in some countries.

Kitti's hog-nosed bat is the smallest species of bat and arguably the world's smallest mammal by body length (the Etruscan Shrew is regarded as the smallest by body mass). It has a reddish-brown or grey coat, with a distinctive pig-like snout. Colonies range greatly in size, with an average of 100 individuals per cave. The bat feeds during short activity periods in the evening and dawn, foraging around nearby forest areas for insects. Females give birth annually to a single offspring.