The World’s Smallest Mammals

Published November 7, 2012
Updated August 20, 2025

Some of the tiniest, cutest, and most fascinating creatures on the planet -- a look at the world's smallest mammals!

Smallest Mammals In The World

The World’s Smallest Mammals: Kitti’s Hog-Nosed Bat

Hog Nosed Bat

Depending on whether you measure by weight or size, Kitti’s Hog-nosed Bat (aka the Bumblebee Bat) is one of the two top contenders for world’s smallest mammal. At an average of 2g (0.071oz), this diminutive species is found in limestone caves along rivers in western Thailand and southeast Burma.

http://www.youtube.com/watch?v=f_BoILxJ_yk

While most cave-dwelling bats huddle together in large groups on cave walls and ceilings, these bats prefer their own space and tend to spread out when resting. They also reproduce very slowly and are particularly vulnerable to disturbances in their habitat.

Etruscan Pygmy Shrew

Losing out to bats in size, the Etruscan shrew, weighing in at 1.8g (0.063oz), can claim the world’s smallest mammal by weight.

Like most shrews, the Etruscan is a voracious predator that uses whisker-guided attacks to eat almost twice its own weight in grubs, worms and insects on a daily basis. It needs all this food to fuel a hyperactive metabolism that requires their teeny tiny hearts to beat 1511 times every second. 

Madame Berthe’s Mouse Lemur

First categorized as a new species in the year 2000 and named after named after the conservationist Madame Berthe Rakotosamimanana, this smallest of the mouse lemurs (and the world’s smallest primate) can only be seen in Madagascar’s Kirindy Mitea National Park.

With a diet made up of insects, small reptiles, fruit and “honeydew”, a sugary secretion produced by the larvae of Flatida coccinea, this nocturnal forager can lower its internal temperature and metabolic rate to conserve water and energy during the dry season.

Pygmy Marmoset

Pygmy Marmoset

To find the world’s smallest true monkey, the Pygmy Marmoset, you’ll need to take a trip to the often flooded, tropical evergreen forests of the Amazon basin. Usually found in family troops of two to fifteen individuals, this omnivorous species has a special liking for certain kinds of tree sap and has evolved a lower jaw specialized for making holes in bark. 

The World’s Smallest Mammals: Baluchistan Pygmy Jerboa

Tied in first place with the African Pygmy Mouse for smallest rodent in the world, the Baluchistan Pygmy Jerboa looks like a furry face with a tail and legs.

http://www.youtube.com/watch?v=-GKWOml84n8

Only living in the shifting sand dune desert of Pakistan, the Pigmy Jerboa can also alter its metabolism, which it does on a daily basis, slowing down its breathing and circulation to make up for a barely nutritious diet of succulents, windblown seeds and any other digestible vegetation.

author
Savannah Cox
author
Savannah Cox holds a Master's in International Affairs from The New School as well as a PhD from the University of California, Berkeley, and now serves as an Assistant Professor at the University of Sheffield. Her work as a writer has also appeared on DNAinfo.
editor
John Kuroski
editor
Based in Brooklyn, New York, John Kuroski is the editorial director of All That's Interesting. He graduated from New York University with a degree in history, earning a place in the Phi Alpha Theta honor society for history students. An editor at All That's Interesting since 2015, his areas of expertise include modern American history and the ancient Near East. In an editing career spanning 17 years, he previously served as managing editor of Elmore Magazine in New York City for seven years.
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Cox, Savannah. "The World’s Smallest Mammals." AllThatsInteresting.com, November 7, 2012, https://allthatsinteresting.com/smallest-mammals. Accessed August 23, 2025.