Animal Facts for Kids

Scientists use different classifications in order to organize the way that living organisms are formed.

The different levels of classification include: Phylum, Class, Order, Family, Genus and Species.

Animals are classified based on the differences that they have. Some animals have skeletons, some live in the water and some fly, to name a few.


The two largest groups of animals are vertebrates and invertebrates.

Vertebrates are animals that have spines, or that have backbones.

Invertebrates do not have spines or backbones.


Most of the animals in the world are considered invertebrates. These include octopus, squid, insects, arachnids, star fish, jelly fish, lobsters, crabs and other creatures.

The invertebrates that live on the land are mostly small but those that live in the water sometimes grow extremely large because the water can support their large bodies.



Vertebrates only make up 5% of all the animals that live on the Earth. Vertebrates are divided into different classes or groups and many of these are fish.

Fish have different classes such as bony fish and fish. Amphibians, reptiles, birds and mammals are also different classes of Vertebrates.



A fish has different characteristics such as living under the water and they use gills instead of lungs to breath. Fish have scales, fins and are cold blooded.

Cold blooded means that an organism cannot control their own body temperature and it changes based on the environment that they live in.

Most fish lay eggs. Sharks and Stingrays are also fish. A fish’s body is made out of cartilage. Some fish live in water and on land.



Amphibians is another group of animals that includes animals such as toads, frogs, salamanders, and more. Amphibians are cold blooded, and they live on the land and in the water.

Amphibians lay eggs in the water and they have cold, smooth skin. The eggs that Amphibians lay are usually soft. Amphibians get oxygen through their skin.

Amphibians must go through metamorphosis or a change in order to become adult Amphibians.

Amphibians are the only vertebrates that go through metamorphosis.



Turtles, lizards, snakes, crocodiles and more are considered reptiles. Reptiles are cold blooded, and they are air breathing animals.

Reptiles cannot breathe under water. You can tell the difference between a reptile and an amphibian based on their skin. The skin of a reptile is dry and scaly.

Reptiles lay eggs. These eggs are different than other animals. These eggs are laid out of water and they have hard shells. Sea Turtles are reptiles too, they just adapted to live in water.



Birds are animals that are easy to recognize because of their different features. Birds are the only animals that have feathers and they breathe only air.

Birds have two legs and wings, but not all birds are able to fly. Birds also have beaks.

Birds are warm blooded animals. Warm blooded means that an organism can keep a constant temperature.

Birds lay eggs that have hard shells. Birds also care for their young after they have them.

Penguins are birds that do not fly. They dive and swim instead of flying.



Mammals are another group of animals. Mammals are warm blooded and they breath air. Humans are mammals.

All mammals have some fur or some type of hair, even if some have less than other.

Most mammals give birth to live young and not eggs. Mammals are the only animals that have ears that stick out.

Mammals drink milk from their mothers. When mammal’s breath, they use their lungs.

Some mammals live in water, such as whales, but they still use their lungs to breath. Bats are the only mammals that fly.


Facts About Animals:

  • Classifying animals helps us to understand their behaviors.
  • Scientists have studied how to classify animals for hundreds of years.
  • To classify means to sort something in to groups to show how they are alike.
  • People are vertebrates and mammals.
  • Lions, fish, birds, snakes and turtles all have backbones and they are vertebrates.
  • Butterflies and grasshoppers do not have backbones, so they are invertebrates.
  • The smallest mammal in the world is a Bumble Bee Bat.
  • Cold blooded animals use water to get cool and the sun to get warm.

What Did You Learn?

  • Animals are divided in to two groups. What are the groups? Animals are divided in to vertebrate and invertebrates.
  • What is an animal called that has a backbone? An animal that has a backbone is called a Vertebrate.
  • What kind of animal has no backbone or spine? Animals that have no spine or backbone are called invertebrate.
  • Why do scientists classify animals in to different groups? Animals are separated in to two different groups so that they can be studied.
  • What are the five different groups of Vertebrate animals? The five groups of Vertebrate animals are fish, amphibians, reptiles, mammals and birds.