Vertebrates and Invertebrates

All animals can be divided into two main groups. Vertebrates are animals that have a backbone, or spine. Invertebrates are animals that do not have a backbone. Both groups include many different kinds of creatures living all over the world.

Vertebrates

Vertebrates have a skeleton inside their body with a backbone running down the middle. There are five main types of vertebrates: mammals, birds, reptiles, amphibians, and fish. Vertebrates include the largest animals on Earth, like blue whales and elephants. They also include tiny animals like hummingbirds and guppies.

Invertebrates

Invertebrates do not have a backbone or internal skeleton. Some have a hard outer shell instead, like crabs and beetles. Others have soft bodies, like worms and jellyfish. There are far more invertebrate species than vertebrate species. Insects alone make up about 80 percent of all known animal species.

Fun Facts

• The largest invertebrate is the colossal squid, which can be over 30 feet long.
• A giraffe has the same number of neck bones as a human, just seven, but each one is much bigger.
• Earthworms have no backbone, but they do have five hearts.

Did You Know?

About 97 percent of all animals on Earth are invertebrates. For every one animal with a backbone, there are about 32 animals without one!