Eight tiny but mighty mammals on Earth that are as cute as a button

No matter how petite or easy to overlook, these creatures are crucial to maintaining ecological balance, proving that size isn’t everything when it comes to the animal kingdom. To better understand their role in nature, let’s step into their miniature world and take a closer look at eight of the tiniest mammals found around the globe.

1. Bumblebee bat (Craseonycteris thonglongyai)

As big as a large bumblebee, this remarkable bat (Craseonycteris thonglongyai), also known as Kitti’s hog-nosed bat due to its pink pig-like nose, is the world’s smallest mammal by length.

The bumblebee bat was discovered by zoologist Kitti Thonglongya in 1974, and is native to western Thailand and southeast Myanmar. It mostly inhabits limestone caves and measures just between 1.1 to 1.6 inches in length, with an estimated hanging height of 2.4 to 2.75 inches.

Weighing around 2 grams, the species is an efficient predator and primarily feeds on arthropods like beetles, flies, and even spiders, skillfully catching them mid-flight with its mouth, through a process called echolocation. It has a lifespan of up to a decade.

However, the bumblebee bat remains poorly studied, with limited data on its population size and behavior. Habitat disturbances, including tourism, fertilizer collection, and limestone mining, pose significant threats to its survival, which is why it is listed as ‘near threatened‘ on International Union for Conservation of Nature’s (IUCN) Red List of Threatened Species.

2. Mouse lemur (Microcebus genus)

Native to Madagascar, like all lemurs, the mouse lemur holds the title of the world’s smallest primate, with more than 20 recognized species thriving across the island’s forests. These nocturnal animals are skilled foragers, feeding mostly on beetles, which they substitute for fruit, flowers, and leaves, when insect prey is scarce.

Mouse lemurs store fat in their tails and hind legs, using it as energy when food is in short supply. They can accumulate up to 35% of their body weight in reserves and live on top of the island’s forest trees, rarely venturing onto the ground.

The Madame Berthe’s mouse lemur (Microcebus berthae), is not only the tiniest of the mouse lemurs but also the smallest primate in the world. It has an average body length of 3.6 inches and a seasonal weight of around 1.1 ounces.

The species is also listed as ‘critically endangered‘ on the IUCN’s Red List of Threatened Species, with its biggest threats being deforestation and habitat degradation caused by slash-and-burn agriculture, illegal logging, and charcoal production.

3. Etruscan shrew (Suncus etruscus)

No larger than a human thumb and lighter than a penny, the Etruscan shrew (Suncus etruscus), also known as the Etruscan pygmy shrew or the Pygmy white-toothed shrew, holds the title of being the world’s smallest mammal by weight. Tipping the scales at just 1.8-3 grams and measuring 1.4-1.9 inches, the species is native to southern Europe, North Africa, and parts of Asia.

Despite its tiny size, the Etruscan shrew is a fierce and fast hunter, relying on speed and agility to catch its prey. It primarily feeds on insects, larvae, and earthworms, using its sharp sense of touch and lightning-fast reflexes to hunt.

This tiny insectivore has an exceptionally fast metabolism, demanding near-constant feeding to survive. With a heart rate reaching 1,500 beats per minute, the Etruscan shrew must consume nearly twice the amount of food compared to its body weight every day to sustain itself, making it one of the most voracious eaters in the animal kingdom.

The species is currently not endangered. However, habitat loss due to human activity and climate change threaten its long-term survival.

4. Pygmy possum (Burramyidae)

Found in Australia and Papua New Guinea, pygmy possums are a group of nocturnal tree-dwelling marsupials, which range from 2 to 4.7 inches in length and weigh between 0.35 and 1.76 oz.

As skilled climbers, pygmy possums rely on their prehensile tails and sharp claws to move effortlessly through the treetops in search of food. Their diet primarily consists of nectar, pollen, insects, and small fruits, making them important pollinators within their ecosystems as they facilitate pollen transfer while foraging on flowering plants such as banksias and eucalypts.

The pygmy possum family is divided into two groups: the genus Burramys, with only one surviving species—the mountain pygmy possum—and the genus Cercartetus, which includes the western, eastern, Tasmanian, and long-tailed pygmy possums.

The Tasmanian pygmy possum (Cercartetus lepidus), found in Southeastern Australia, is considered the world’s smallest marsupial, measuring up to 3 inches in length and weighing as little as 0.2 ounces.

5. American shrew mole (Neurotrichus gibbsii)

One of the smallest moles found in North America, the American shrew mole (Neurotrichus gibbsii) weighs just 0.25 to 0.39 ounces, while its body measures less than 2 inches in length. The species can be spotted through central California and southern British Columbia, spanning areas from the Pacific Ocean to the Cascade and Sierra Nevada mountains.

Unlike its fully subterranean relatives, which are much larger in comparison, the American shrew mole is semi-fossorial, meaning it spends time both underground and on the forest floor.

While earthworms are its preferred food, the species also feeds on insect larvae, snails, slugs, centipedes, sow bugs, fungi, and seeds, using its sensitive nose and long claws to forage. Similar to the Etruscan shrew, the American shrew mole has a fast metabolism, meaning it must eat constantly to survive.

Despite being listed as species of ‘least concern‘ by the IUCN, these moles still face threats due to climate change, habitat loss, and destruction caused by residential and commercial developments, as well as agriculture.

6. Least weasel (Mustela nivalis)

Though slightly larger than some others in this category, the least weasel (Mustela nivalis)—also called little weasel—is still the smallest true carnivore on Earth. It’s native to Eurasia, North America, and North Africa, but has been introduced to other parts of the world.

Small but fierce, the least weasel is just 4-10 inches long and weighs a mere 0.9 ounces, making it lighter than a slice of bread. However, regardless of its size, this tiny mammal is remarkably agile and efficient.

A specialized predator, the least weasel is a relentless hunter with an insatiable appetite. It primarily hunts mice and small voles. Although, it may also feed on insects and ground-nesting birds when its preferred prey is scarce. It consumes up to a third of its body weight daily, to fuel its high-energy lifestyle.

The IUCN classifies the species as of ‘least concern‘ due to its widespread distribution and stable population. However, it faces threats from human trapping, habitat loss, prey decline, poisoning, and natural predation.

7. Pygmy marmoset (Cebuella genus)

Native to Brazil, Colombia, Ecuador, and Peru, pygmy marmosets hold the title of the world’s smallest true monkey. They are also known as ‘finger monkeys’ because they are small enough to perch comfortably on a person’s finger.

Based on genetic differences, as well as their geographic distribution, the genus is split into two species: the western pygmy marmoset (Cebuella pygmaea) and the eastern pygmy marmoset (Cebuella niveiventris).

Both species share similar measurements, with a head and body length of about 6 inches and a tail slightly longer than their body. A fascinating aspect of their anatomy is that the skulls of Pygmy marmosets are remarkably small, measuring up to 1.5 inches, roughly the size of an AirPod!

Because of their tiny size, these monkeys are incredible jumpers, capable of leaping up to 16 feet. Their long tails help them stay balanced as they move through the dense rainforest canopy. The species mainly feeds on tree sap, using sharp incisors to gnaw through the bark and access the sticky fluid inside.

Pygmy marmosets are classified as ‘vulnerable‘ on the IUCN Red List of Threatened Species, facing risks from habitat loss and pet trade.

8. Baluchistan pygmy jerboa (Salpingotulus michaelis)

One of the smallest rodents in the world, the Baluchistan pygmy jerboa (Salpingotulus michaelis), also known as the dwarf three-toed jerboa, is native to Pakistan but may also be found in parts of Afghanistan.

Reaching an average length of 1.7 inches, this nocturnal animal has a tail nearly twice its body size, measuring 3.1 inches. Adult females are incredibly lightweight, weighing just 0.11 ounces.

Despite their tiny size, Baluchistan pygmy jerboas have exceptionally long hind legs and large feet, enabling them to make impressive leaps across the harsh desert landscape. The species feeds on wind-blown seeds and succulent leaves, relying on these food sources for both nourishment and hydration in its arid habitat.

There is currently insufficient information to determine the Baluchistan pygmy jerboa’s conservation status according to the IUCN. There are no confirmed threats to its survival at present due to limited research on its population and habitat.