Nancy Deacon

Third Grade Teacher at Augusta Preparatory Day School, Augusta, Georgia

Vertebrate Animal Groups

    There are so many different kinds of animals in the world that scientists had to divide them into two main categories, or groups, in order to study them.  The two main groups are vertebrates and invertebrates.


    Vertebrates are animals with backbones, or skeletons, on the inside of their bodies.  There are so many vertebrates, or animals with backbones, that scientists have divided them into five main groups, or classes.  These five classes are reptiles, mammals, fish, birds, and amphibians.  Some animals are cold-blooded, which means that the animal's body temperature changes with the air temperature around it.  Some animals are warm-blooded which means that the animal's body temperature stays the same temperature no matter what the air temperature around it is.

    Let's take a look at each of the vertebrate groups:


    One of the oldest groups of backboned animals on Earth are reptiles.  Some examples of reptiles are snakes, alligators, and lizards.
Some characteristics of reptiles are:
                -They are covered with scaly skin.
                -Most hatch from eggs.
                -They breathe with lungs.
                -They live mostly on land.  Some live in the water.
                -They are cold-blooded.
                -Young take care of themselves.


    Amphibians were the first group of animals to adapt to living on land.  Amphibians spend the first part of their lives in the water and
the last part of their lives on land.  They go through a metamorphosis.  ("Metamorphosis" comes from a Greek word which means "change".  "Amphibian" means "double life".)
    Some characteristics of amphibians are:
                -They lay eggs in water, and the young hatch from eggs.
                -They are cold-blooded.
                -They begin life in water and breathe through gills.  They breathe with lungs when they live on land.
                -Young take care of themselves.
                -They are covered with a thick skin.


    Mammals are the only warm-blooded group of animals!  Humans are a member of this group of vertebrates, so mammals include the highest order of animals that have the capability to think to solve problems.
    Some characteristics of mammals are:
                -They are warm-blooded.
                -They are born live.
                -They breathe with lungs.
                -They drink mother's milk.
                -They are covered with hair or fur.
                -Some mammals, such as whales, live in water.  Bats are mammals that fly.  Otherwise, mammals live on land.
                -Young must have care from their parents for a while.


    Birds are vertebrates that fly.  Their bones are hollow which makes them light enough to be lifted into the air with wings.
    Some characteristics of birds are:
                -They hatch from eggs.
                -They are cold-blooded.
                -They are covered with feathers.
                -They breathe with lungs.
                -They live on land, on water, and in the air.
                -The young must be cared for for a while.


    Fish are vertebrates that live only in water.
    Some characteristics of fish are:
                -They breathe though gills.
                -They hatch from eggs.  (Some sharks give live birth.)
                -They are cold-blooded.
                -The young take care of themselves from birth.
                -They are covered with scales.

All animals have certain behaviors that help that animal survive.  These behaviors are called behavioral adaptations.  One example of this is how animals survive the winter.

Learn some cool facts about how animals spend the winter (behavioral adaptations).

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 (January, 2001)

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