What Is a Reptile? Definition, Traits & Examples
Reptiles are scaly, mostly egg-laying vertebrates — snakes, lizards, turtles, crocodilians, and tuatara. Traits, cold-blooded myths, and living groups explained.
Global Animal Guide · July 10, 2026
Photo: Obtained from Molly Ebersold of the St. Augustine Alligator Farm · Public domain · source · credits
Quick answer
Reptiles are vertebrates with dry, scaly skin (or scutes), lungs throughout life, and usually amniotic eggs laid on land. Living groups include lizards and snakes, turtles and tortoises, crocodilians, and the tuatara. Most are ectotherms. In modern phylogeny, birds are nested within reptiles — everyday language still treats birds separately.
Last updated: July 2026.
Key traits
- Keratinous scales or bony scutes
- Amniotic eggs (or live birth derived from that strategy)
- Lungs at all life stages (no gill-breathing adults)
- Usually ectothermic
- Cloaca present
Living orders (simplified)
Squamata — lizards, snakes, amphisbaenians
Testudines — turtles and tortoises
Crocodilia — crocodiles, alligators, caimans, gharials
Rhynchocephalia — tuatara (New Zealand)
Related reading
Frequently asked questions
Are snakes reptiles?
Yes — snakes are elongated lizards in evolutionary terms, within order Squamata.
Are turtles amphibians?
No — turtles are reptiles with shells; amphibians have moist skin and typically aquatic larvae.
Do all reptiles lay eggs?
No — many snakes and lizards give live birth (viviparity or ovoviviparity).
Are dinosaurs reptiles?
Non-bird dinosaurs were reptiles; birds are their living descendants.