The World's Tiniest Animals Fractions Article for Students

Last March, Florida’s ZooTampa welcomed a baby pygmy hippopotamus. The bouncing baby girl was about the size of a housecat, weighing just 10 pounds!

Pygmy hippos are shy creatures found in West Africa. They’re so rare that scientists know little about how they behave in the wild. They’re also endangered: Fewer than 3,000 pygmy hippos are left in the wild. “Every birth is a sign of hope and helps save endangered species for future generations to enjoy, appreciate, and cherish,” says Chris Massaro, senior vice president of zoological operations at ZooTampa.

When fully grown, the pygmy hippo will be almost 6 feet long and weigh about 600 pounds. That might not seem so small to you. But its much larger cousin, the common hippopotamus, can measure up to 16.5 feet long and tip the scales at more than 9,000 pounds!

Read on to learn about more mini creatures that are the tiniest members of their animal families.

Last March, ZooTampa in Florida welcomed a new baby. A baby pygmy hippopotamus, that is! The newborn female weighed just 10 pounds. That’s about the size of a housecat!

Pygmy hippos are shy creatures found in West Africa. They’re so rare that scientists don’t know much about how they behave in the wild. They’re also endangered. Fewer than 3,000 pygmy hippos are left in the wild. “Every birth is a sign of hope,” says Chris Massaro, one of ZooTampa’s leaders.

The pygmy hippo will grow up to be almost 6 feet long. It will weigh about 600 pounds. That might not seem so small to you. But its much larger cousin, the common hippopotamus, can measure up to 16.5 feet long—and tip the scales at more than 9,000 pounds!

Read on to learn about more mini creatures. They’re all the tiniest members of their animal families.

Write and simplify fractions to see how some teeny-tiny animals compare with their larger relatives. Record your work and answers on our answer sheet.

An average baby pygmy hippo weighs 15 pounds at birth. It will grow to be 600 pounds as an adult. What fraction of an adult weight is a pygmy hippo’s birth weight?

Courtesy of JJavontae Murphy via Creative Commons/Wikipedia

Dwarf latern shark

The deep ocean is full of some of the most unusual creatures on the planet. One of them is the world’s smallest shark: the dwarf lantern shark. These sharks live off the coasts of Colombia and Venezuela. Only a few have ever been captured, so scientists know little about them. But they do know that the dwarf lantern shark—like many deep-water creatures—is bioluminescent, meaning it makes its own light.

Similar to fireflies, each species of bioluminescent shark flashes a unique pattern, says shark expert George Burgess. He discovered the dwarf lantern shark in 1964!

“The flashing patterns probably act like signs in a dark world,” Burgess says. That may help the teeny-tiny sharks attract prey or track down their own kind to mate with.

Some of Earth’s most unusual creatures live in the deep ocean. One of them is the world’s smallest shark! The dwarf lantern shark lives off the coasts of Colombia and Venezuela. Only a few have ever been captured, so scientists know little about them. But they do know that the tiny shark is bioluminescent. That means it makes its own light.

George Burgess is a shark expert. He discovered the dwarf lantern shark in 1964. There are other species of shark that glow too, he says. But each one flashes a unique pattern. “The flashing patterns probably act like signs in a dark world,” says Burgess. They may help the little sharks attract prey or track down their own kind to mate with.

A dwarf lantern shark is 16 centimeters long. Write a fraction that compares its length with that of its big cousin, the great white shark, which can grow as long as 600 centimeters.

Every morning, troops of pygmy marmosets wake up high in the rainforest canopy of the western Amazon of South America. It’s time for breakfast. Most primates are omnivores, eating both plants and animals. But the pygmy marmoset—the smallest monkey in the world at just 13 centimeters long—dines on something a little different. This miniature monkey uses its sharp lower teeth to gouge holes into trees. Then the marmoset eats the sap that
oozes out.

Twice a year, pygmy marmoset females give birth to twin babies. Each newborn is about the size of a human thumb! The father takes care of the babies after they’re born. When it’s time for dad to find food, he carries them around on his back, piggyback style.

Pygmy marmosets live in the Amazon rainforest of South America. They sleep high in the treetops—and wake up hungry for breakfast! Most monkeys are omnivores. That means they eat both plants and animals. But the pygmy marmoset dines on something different. It uses its sharp lower teeth to dig holes in tree trunks. Then it eats the sap that oozes out.

Pygmy marmosets are the smallest monkeys in the world. They measure just 13 centimeters long. Twice a year, females give birth to twin babies. Each newborn is about the size of a human thumb! The father takes care of the babies after they’re born. When he needs to go look for food, he carries them along on his back!

A pygmy marmoset weighs 128 grams. A common marmoset weighs 250 grams. Write a fraction that compares the pygmy’s weight with the common marmoset’s weight.

Marmosets’ tails are longer than their bodies. A common marmoset’s body is 15 centimeters long, but its tail is 35 centimeters! What fraction of a common marmoset’s total length (body and tail) is made up of its tail?

At birth, a pygmy marmoset is 1/4 of their mother’s body weight. If an adult pygmy marmoset weighs 128 grams, how much does each baby weigh?

National News/ZUMA Press

Discovering the world’s smallest frog is no easy task. Just ask Christopher Austin. He’s a herpetologist—a scientist who studies amphibians and reptiles.

Austin was recording frog calls at night in the tropical forest of Papua New Guinea when he heard an unfamiliar, high-pitched noise coming from the forest floor. He searched, but he couldn’t find the clamoring critter. Finally, Austin stuffed a handful of leaves from the ground into a bag. The next morning, he examined the contents.

“We saw this small thing hop off a leaf,” he says. “We were surprised when we realized it was a really tiny frog!”

The frog, named Paedophryne amauensis, is just 8 millimeters long and weighs 0.1 grams, which is as heavy as a toothpick! These diminutive dimensions make it not only the world’s tiniest frog but also the world’s smallest vertebrate, or animal with a backbone!

Discovering the world’s smallest frog isn’t easy. Just ask Christopher Austin. He’s a herpetologist. That’s a scientist who studies amphibians and reptiles.

Years ago, Austin was working in the tropical forest of Papua New Guinea. He was trying to record frog calls at night. He heard a tiny chirp coming from the forest floor. He searched the ground, but he couldn’t find whatever was making the noise. Finally, Austin grabbed a handful of leaves and stuffed them into a bag. The next morning, he took a closer look.

“We saw this small thing hop off a leaf,” he says. “We were surprised when we realized it was a really tiny frog!”

Austin realized the frog was an undiscovered species. It was just 8 millimeters long and weighed 0.1 grams—as light as a toothpick! That makes it the world’s tiniest frog. It’s also the world’s smallest animal with a backbone!

An adult American bullfrog is 20 centimeters long. The world’s tiniest frog is 8 millimeters long. What fraction of the bullfrog’s length is the tiniest frog’s length? (Hint: There are 10 millimeters in 1 centimeter.)

An American bullfrog weighs 750 grams. The tiniest frog weighs 0.1 grams. What fraction of the bullfrog’s weight is the tiniest frog’s weight? (Hint: The denominator and numerator of your fraction should be whole numbers.)

Joel Sartore/Photo Ark

Madame Berthe's mouse lemur

Primates are the group of animals that includes monkeys, apes, and humans. The smallest member of this group is a tiny animal with a big name: Madame Berthe’s mouse lemur. This petite primate is just
4 inches long.

These teensy lemurs live in the trees of Madagascar, an island off the east coast of Africa. Madame Berthe’s mouse lemurs are extremely quick, says Chris Smith, an educator at the Duke Lemur Center in North Carolina. The lemurs’ speed and small size make them talented insect catchers. “They’re small enough to run right inside a flower where a moth is feeding, grab it, and gobble it down,” Smith says.

Primates are the group of animals that includes monkeys, apes, and humans. The smallest member of this group is a tiny animal with a big name. It’s called Madame Berthe’s mouse lemur. And it’s just 4 inches long!

These teensy lemurs live in the trees of Madagascar. That’s an island off the east coast of Africa. They move extremely quickly, which helps them catch insects, says Chris Smith. He’s an educator at the Duke Lemur Center in North Carolina. “They’re small enough to run right inside a flower where a moth is feeding,” says Smith. “Then they grab it and gobble it down.”

An adult Madame Berthe’s mouse lemur weighs 30 grams. The larger ring-tailed lemur weighs 3,000 grams. What fraction of the ring-tailed’s weight is the mouse lemur’s weight?

When a Madame Berthe’s mouse lemur is born, it weighs 0.2 grams—the same as a raindrop! Write a fraction to express the newborn mouse lemur’s weight compared with its weight as an adult.