The Smallest Animal in the World Weighs Less Than 1 Milligram

The smallest species of frog weighs just 0.0001 ounces (a few milligrams). SolStock / Getty Images

The natural world is home to some incredibly tiny creatures. From miniature mammals to tiny amphibians, many of the smallest animals in the world weigh less than a grape and are smaller than an average 5-year-old's hand.

There's also some science behind why we as humans find these tiny animals to be so cute. The positive dopamine hits that we get from baby-like features likely evolved so that we would care for and protect the young. Let's take a look at the smallest of these cuties by weight, length and type.

6 Impossibly Light Animals

1. Paedocypris Fish

The Paedocypris, considered the world's smallest vertebrate, weighs 0.00004 ounces (less than a milligram). These tiny organisms inhabit acidic peat swamps in Southeast Asia.

2. Tiny Frog

This species weighs just 0.0001 ounces (a few milligrams). Found in Papua New Guinea, its small size allows it to live in moist leaf litter.

3. Bee Hummingbird

The bee hummingbird, the smallest bird in the world, weighs just 0.06 to 0.07 ounces (1.6 to 2 grams). Found in Cuba, it is known for its iridescent feathers and incredibly fast wingbeats.

4. Bumblebee Bat

The bumblebee bat, also known as Kitti's hog-nosed bat, is the world's smallest mammal by weight, tipping the scales at just 0.07 ounces (2 grams). Found in Thailand and Myanmar, this tiny creature is no bigger than a large bumblebee.

5. White-toothed Pygmy Shrew

Weighing only about 0.04 to 0.09 ounces (1.2 to 2.7 grams), the white-toothed pygmy shrew is one of the tiniest mammals in Europe. They are 20 times lighter than your average mouse. Despite its size, it has an incredibly high metabolism and must eat frequently.

6. Pygmy Seahorse

Weighing just 0.1 ounces (a few grams), the pygmy seahorse blends seamlessly with coral reefs. Its small size and camouflage make it one of the most elusive marine animals.

9 Incredibly Short Animals

1. Fairyfly

Fairyflies, a type of wasp, are the smallest insects, measuring just 0.006 inches (0.015 centimeters) in length. Despite their name, they are parasitic and play a role in controlling other insect populations.

2. Paedocypris Fish

In addition to being lightweight, the Paedocypris fish measures just 0.3 inches (0.76 centimeters) in length. It's often considered the smallest known fish and vertebrate by body length. Its translucent body adds to its unique appearance.

3. Tiny Frog

This amphibian measures only 0.3 inches (0.76 centimeters) long, making it the smallest known amphibian in size. Its diminutiveness allows it to navigate the leaf litter undetected.

4. Brookesia nana

Brookesia nana, the world's smallest chameleon, is so tiny it could comfortably perch on the tip of your finger. Just like its larger relatives, it's a master of camouflage, blending into leaf litter with microscopic precision

5. Bumblebee Bat

With a body length of about 1.1 to 1.3 inches (2.8 to 3.3 centimeters), the bumblebee bat is incredibly compact. Its small wingspan allows it to flutter through dense forests with ease.

6. Pygmy Seahorse

Pygmy seahorses measure about 0.9 inches (2.29 centimeters) in length. These creatures are masters of disguise, blending seamlessly with the coral they inhabit.

7. Pygmy Shrew

This light animal's body is about 1.4 inches (3.5 centimeters) long. Despite its size, the itty-bitty mammal has an incredibly high metabolism and must eat frequently.

8. Bee Hummingbird

The bee hummingbird measures only 2 inches (5.08 centimeters) in length from beak to tail. Despite its tiny size, it plays a crucial role as a pollinator in its ecosystem.

9. Madame Berthe's Mouse Lemur

This mouse lemur measures about 3.6 to 3.9 inches (9.14 to 9.91 centimeters) in body length. These animals, found in the forests of southwestern Madagascar, are considered the world's smallest living primate.

The Smallest of Each Type of Animal

Smallest Mammal: Pygmy Shrew

While the bumblebee bat is the smallest living mammal by weight, the Pygmy shrew — which has an average weight around 0.06 ounces (1.8 grams) and measures about 1.4 inches (3.5 centimeters) in body length, excluding the tail — is often considered the smallest mammal.

Smallest Bird: Bee Hummingbird

bee hummingbird feeding — Bee hummingbird.
Roberto Machado Noa / Getty Images

The bee hummingbird is the smallest bird, weighing only 0.06 to 0.07 ounces (1.6 to 2 grams) and measuring 2 inches (5.08 centimeters) in length.

Smallest Reptile: Brookesia nana

Brookesia nana, a newly discovered species of chameleon, is the smallest known reptile. Measuring just 0.53 inches (1.35 centimeters), this tiny lizard lives in Madagascar.

Smallest Amphibian: Tiny Frog

The tiny frog (Paedophryne amauensis) measures just 0.3 inches (0.76 centimeters) in length. It thrives in the humid forests of Papua New Guinea.

Smallest Fish: Paedocypris

The Paedocypris holds the title of the world's smallest fish, measuring only 0.3 inches (0.76 centimeters) in length. These fish are adapted to survive in extreme, acidic environments.

Smallest Insect: Fairyfly

Fairyflies may sound like something out of a fantasy novel, but these microscopic wasps are the real deal—so small they can slip through the tiniest spaces in search of insect eggs to parasitize, making them nature's ultimate stealthy population controllers

Smallest Monkey

The pygmy marmoset, often called the world's smallest monkey, weighs about 3.5 ounces (100 grams) and measures around 5-6 inches (12.7 to 15.2 centimeters) in body length. These primates are native to the Amazon rainforest and are known for their agility and vocalizations.

The natural world's tiny creatures remind us that size isn't everything. These smallest known species each play an important role in their ecosystems, proving that even the tiniest animals can have a big impact.

We created this article with AI technology, then made sure it was fact-checked and edited by a HowStuffWorks editor.