Blue whales are the largest animals that have ever lived—they’re even bigger than dinosaurs! Blue whales reach 34 meters (110 feet) long and weigh as much as 172,365 kilograms (190 tons). That’s more than twice as long as a city bus!
The world’s largest dinosaur may have been Patagotitan mayorum, which became extinct about 102 million years ago. Patagotitan may have been 36.5 meters (120 feet) long and weighed as much as 62.6 metric tons (69.0 tons). That’s heavier than some airplanes.
Like all dinosaurs, Argentinosaurus was a reptile. Today, the world’s largest reptile is the saltwater crocodile. “Salties” stretch up to 7 meters (23 feet) and weigh as much as 2 metric tons (2.2 tons). They are about half as long as the world record for the women’s long jump.
The bush elephant, a species of African elephant, is the world’s largest terrestrial animal. Bush elephants stand up to 4 meters (13 feet) tall and can weigh 6,000 kilograms (nearly 7 tons). They weigh about the same as a school bus.
The largest bird on Earth is the common ostrich. An ostrich can stand more than 2 meters (7 feet) tall and weigh more than 150 kilograms (330 pounds). Ostriches stand about the same height as basketball great Shaquille O’Neal.
The largest amphibian in the world is the Chinese giant salamander. This river-dweller stretches to nearly 1.8 meters (6 feet) and weighs as much as 50 kilograms (110 pounds).It weighs about the same as a newborn foal (horse).
The world’s largest fish is the whale shark. This gentle giant can reach 18.8 meters (61.6 feet) in length and weigh as much as 18,143 kilograms (20 tons). That’s about the same size as a small yacht.
Like the world’s largest mammal (the blue whale), the world’s largest invertebrate swims the deep sea. The aptly named colossal squid can stretch more than 13 meters (45 feet) and weigh about 750 kilograms (1,650 pounds). That’s heavier than a motorcycle.
  • Blue whales usually measure about 25 meters (82 feet) long—about the distance around a baseball diamond!
  • A blue whale weighs about 99,790 kilograms (110 tons)—about as much as a railway locomotive!
  • Like the blue whale, all of Earth’s heaviest animals are cetaceans! Other leviathans include the North Pacific right whale, fin whale, bowhead whale, Southern right whale, North Atlantic right whale, sperm whale, humpback whale, sei whale, and grey whale.

an animal able to live both on land and in water.


very large, extinct reptile chiefly from the Mesozoic Era, 251 million to 65 million years ago.


to live in a certain place.


no longer existing.


young horse, mule, or related animal, usually under a year of age.


animal without a spine.

long jump

individual sport where an athlete runs to a set line, then jumps as far as possible.


animal with hair that gives birth to live offspring. Female mammals produce milk to feed their offspring.


animal that breathes air and usually has scales.


group of similar organisms that can reproduce with each other.


having to do with the Earth or dry land.


large boat or ship owned by a single person or group, used for recreation or racing.