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10.2: Vertebrate Characteristics

Difficulty Level: At Grade Created by: CK-12
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What animals have a backbone?

You have a backbone, or vertebrate column, as highlighted here in pink. Can you guess what other animals also have a backbone? Frogs, snakes, birds, and many other animals all have backbones. Animals that have backbones are known as vertebrates.

Introduction to Vertebrates

Vertebrates are animals with backbones. These include fish, amphibians, reptiles, birds, and mammals.

Characteristics of Vertebrates

The primary feature shared by all vertebrates is the vertebral column , or backbone. The vertebral column protects the spinal cord.

Other typical vertebrate traits include:

  • The cranium (skull).
  • An internal skeleton.
  • A defined head region with a brain.

Living vertebrates range in size from a carp species, as little as 0.3 inches, to the blue whale, which can be as large as 110 feet ( Figure below ).

A species of carp and an image of the blue whale (a mammal), the largest living vertebrate, reaching up to 110 feet long. Shown below it is the smallest whale species, Hector's dolphin (about 5 feet in length), and beside it is a human. These images are not to scale. The carp is greatly exaggerated in size and is even smaller than depicted when compared to the blue whale.

Classification of Vertebrates

Vertebrates, or subphylum Vertebrata, are all members of the phylum Chordata. Although there is some disagreement on how to classify animals, the traditional system divides the vertebrates into six classes ( Table below ).

Class Common name
Class Agnatha jawless fishes
Class Chondrichthyes cartilaginous fishes
Class Osteichthyes bony fishes
Class Amphibia amphibians
Class Reptilia reptiles
Class Aves birds
Class Mammalia mammals


  • cranium : Protective brain case; also called the skull.
  • vertebral column : Bony support structure that runs along the back of a vertebrate animal; also called the backbone.
  • vertebrate : Animal with backbone; these include mammals, birds, reptiles, amphibians, and fish.


  • Vertebrates are animals with a backbone.
  • Vertebrates include the mammals, birds, reptiles, amphibians, and fish.


Use the resources below to answer the questions that follow.

  1. What do scientists feel was a key factor in vertebrates getting "big"?
  2. What advantages do big animals have over small animals? Be as complete as you can in your answer.
  3. What advantages do small animals have over big animals? Be as complete as you can in your answer.
  4. What did jaws allow vertebrates to do?
  5. What is a "larvacean"? How does it feed?
  1. What is unique to vertebrates?
  2. What characteristics define Archosaurs? Who belongs to this group? Who are its living members?
  3. What characteristics define Amniotes? Why is this characteristic useful to life on land?


  1. What are some examples of vertebrates?
  2. What are the main features shared by the vertebrates?

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Difficulty Level:

At Grade


7 , 8

Date Created:

Nov 29, 2012

Last Modified:

Nov 04, 2014
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