Vertebrate

Introduction & Top Questions
General features
Natural history
- The cyclostomes
- The chondrichthyes
- The teleostomes
- The tetrapods
Form and function
- External features
- Internal features
  - The skeletal system
  - Tissues and muscles
  - Nervous system and organs of sensation
  - The digestive system
  - The excretory system
  - Respiration and gas exchange
  - The circulatory system
  - The endocrine system
Evolution and paleontology
Classification
- Annotated classification
- Critical appraisal

References & Edit History Quick Facts & Related Topics

Images, Videos & Interactives

Illustration showing examples of vertebrates: a turtle for reptiles, a songbird for birds, a bluegill fish, a salamander for amphibians, and two mammals-a whale and a groundhog.

Observe the hagfish's horny teeth and scaleless exterior covering a cartilaginous skeleton

southern stingray (Dasyatis americana or Hypanus americanus)

Bull shark (Carcharhinus leucas) swimming close to the sandy ocean floor in clear blue water.

American paddlefish (Polyodon spathula) swimming underwater, showing its long, flat snout and streamlined body.

At a Glance

vertebrate summary

Quizzes

Sea otter (Enhydra lutris), also called great sea otter, rare, completely marine otter of the northern Pacific, usually found in kelp beds. Floats on back. Looks like sea otter laughing. saltwater otters

Animal Group Names

Deadliest Animals Quiz

Young chimpanzee dressed in a shirt and sweater vest, scratching his head thinking. (primates)

Wild Words from the Animal Kingdom Vocabulary Quiz

Match the Baby Animal to Its Mama Quiz

The bearded vulture (Gypaetus barbatus) is seen in Switzerland on December 2024

Animal Factoids

Related Questions

How are birds more closely related to reptiles than to mammals?
How did bone and cartilage contribute to vertebrate evolution?
How did jaws evolve from gill arches in vertebrates?
How did reptiles diversify into land-dwelling, marine, and flying forms?
How did the extinction of dinosaurs affect the diversification of mammals?
How did the notochord function in the earliest vertebrates?
How do caecilians differ from frogs, toads, and salamanders?
How do feathers distinguish birds from other vertebrates?
How do fish eggs develop in open water and freshwater habitats?
How do frogs and toads care for eggs and tadpoles in different habitats?
How do placental mammals and marsupials differ in the development of their young?
How do reptiles differ from amphibians in their skin and development?
How do sharks and rays reproduce?
How do the three middle-ear bones of mammals transmit sound?
How do vertebrates contribute to human food supplies and recreation?
How do vertebrates differ from invertebrates?
How does a vertebral column support a vertebrate’s body?
How does an amniotic egg help reptiles reproduce on land?
How does direct development change the life cycle of some amphibians?
How does the mammalian diaphragm help with breathing?
How is a notochord different from a vertebral column?
What features distinguish ray-finned fishes from lobe-finned fishes?
What fossil evidence connects birds with feathered dinosaurs?
When did dinosaurs first appear and when did most dinosaurs become extinct?
Which animals belong to the jawless fish group called cyclostomes?
Which reptile traits allow embryos to develop in dry conditions?
Which sense organs are concentrated in the head of vertebrates?
Why are birds considered a clade while reptiles can be considered a paraphyletic group?
Why are some birds unable to fly despite having wings?
Why do many fish lay very large numbers of eggs?
Why is the traditional group called fishes not considered a single evolutionary lineage?
Why were the earliest tetrapods still dependent on water?
What is the main characteristics that define vertebrates?
How are vertebrates classified in terms of their morphology?
How do amphibians differ from reptiles in terms of reproduction?
What is a ray?
How do rays differ from sharks?
What makes the tails of many stingrays dangerous?
What are the main characteristics of pigeons?
What is unique about pigeon parenting?
What led to the extinction of the passenger pigeon?
What are the physical characteristics of sharks?

Science Birds, Reptiles & Other Vertebrates

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External Websites

University of California Museum of Paleontology - Introduction to the Vertebrates
Biology LibreTexts - Vertebrates
Georgia Tech Biological Sciences - Organismal Biology - Animals: Vertebrates
Palomar College - Classes of Vertebrates
University of Central Florida Pressbooks - General Biology - Introduction to Vertebrates
National Center for Biotechnology Information - PubMed Central - Vertebrate Reproduction

Britannica Websites

Articles from Britannica Encyclopedias for elementary and high school students.

vertebrate - Children's Encyclopedia (Ages 8-11)
vertebrate - Student Encyclopedia (Ages 11 and up)

Vertebrate

animal

Also known as: Craniata, Vertebrata

Written by

Malcolm T. Jollie

Professor of Biological Sciences, Northern Illinois University, De Kalb, 1965–88. Author of Chordate Morphology.

Malcolm T. Jollie

Fact-checked by

Britannica Editors

Encyclopaedia Britannica's editors oversee subject areas in which they have extensive knowledge, whether from years of experience gained by working on that content or via study for an advanced degree....

Britannica Editors

Last updated

Nov. 6, 2026 •History

Vertebrate, any animal of the subphylum Vertebrata, the predominant subphylum of the phylum Chordata. They have backbones, from which they derive their name. The vertebrates are also characterized by a muscular system consisting primarily of bilaterally paired masses and a central nervous system partly enclosed within the backbone. The subphylum is one of the best known of all groups of animals. Its members include the classes Agnatha, Chondrichthyes, and Osteichthyes (all fishes); Amphibia (amphibians); Reptilia...

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