reptile

Introduction & Top Questions
General features
- Importance
- Size range
- Distribution and ecology
  - North temperate zone
  - Central and South America
  - Asia
  - Australia
  - Africa
Natural history
- Life cycle and life history
  - Courtship and fertilization
  - Embryonic development and parental care
- Growth and longevity
Behaviour
- Defense
  - Avoidance and noise
  - Body form and posturing
  - Display of colour
  - Striking and biting
  - Spitting
  - Use of the tail
  - Balling
  - Odours
- Feeding habits
- Locomotion
  - Walking and crawling
  - Clinging and climbing
  - Swimming
  - Flying
Form and function
- External covering
- Internal features
  - Skeletal system
  - Skull and dentition
  - Nervous system
  - Circulatory system
  - Respiratory system
  - Digestive and urogenital systems
- Sense organs
  - Sight
  - Hearing
  - Chemoreception
- Thermal relationships
Evolution and paleontology
- Historical development
- Fossil distribution
Classification
- Distinguishing taxonomic features
- Annotated classification
- Critical appraisal

References & Edit History Quick Facts & Related Topics

Images, Videos & Interactives

A painted turtle (Chrysemys picta) with a dark shell and red and yellow markings rests on a rock near water, surrounded by green aquatic plants.

common king snake

Five Nile crocodiles (Crocodylus niloticus) rest on a sandy bank beside green water, with vegetation at the edge.

black girdle-tailed lizard (Cordylus nigra)

A tuatara (Sphenodon punctatus) with rough, spiky skin and a long tail rests on the ground near the entrance of a burrow, surrounded by grass and dirt.

Illustration showing specialized structures in lizards: the frilled lizard with its large neck frill extended, an anole displaying its red throat dewlap, a water lizard's dorsal sail, the fan-shaped toes of a fan-footed gecko, and the fringed toes of a fringe-toed lizard.

Vertebrate species counts

A Komodo dragon (Varanus komodoensis) walks through grassy terrain with green hills and scattered trees in the background on Komodo Island.

Fascinating facts about turtles

Close-up of a king cobra overlaid with question marks, a drawn crown, and an arrow pointing to the snake

At a Glance

Five Nile crocodiles (Crocodylus niloticus) rest on a sandy bank beside green water, with vegetation at the edge.

reptile summary

Related Questions

A painted turtle (Chrysemys picta) with a dark shell and red and yellow markings rests on a rock near water, surrounded by green aquatic plants. — painted turtle (Chrysemys picta) Painted turtle (Chrysemys picta).

reptile

animal

Also known as: Reptilia

Written by

Herndon G. DowlingAll

Fact-checked by

Britannica Editors

Last updated

Nov. 8, 2026 •History

reptile, any member of the class Reptilia, the group of air-breathing vertebrates that have internal fertilization, amniotic development, and epidermal scales covering part or all of their body. The major groups of living reptiles—the turtles (order Testudines), tuatara (order Rhynchocephalia [Sphenodontida]), lizards and snakes (order Squamata), and crocodiles (order Crocodylia, or Crocodilia)—account for over 12,500 species. Birds (class Aves) share a common ancestor with crocodiles in subclass Archosauria and are technically one lineage of reptiles,...

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