Reptiles Study Sheet
1. Introduction to Reptiles
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Definition: Reptiles are cold-blooded vertebrates with scaly skin, belonging to the class
Reptilia.
Characteristics:
○ Ectothermic (cold-blooded)
○ Dry, scaly skin
○ Lay eggs with leathery shells (oviparous) or give live birth (viviparous)
○ Breathe with lungs throughout life
2. Classification
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Order Testudines: Turtles and tortoises
○ Examples: Painted turtle, Galápagos tortoise
Order Squamata: Lizards and snakes
○ Suborders:
■ Lacertilia: Lizards (e.g., Komodo dragon, gecko)
■ Serpentes: Snakes (e.g., cobra, python)
Order Crocodylia: Crocodiles, alligators, caimans, and gharials
○ Examples: Nile crocodile, American alligator
Order Rhynchocephalia: Tuataras
○ Example: Tuatara (found in New Zealand)
3. Physiology
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Skin and Scales:
○ Made of keratin
○ Provide protection and reduce water loss
Respiratory System:
○ Primarily use lungs
○ Some can absorb oxygen through the skin (e.g., some aquatic turtles)
Circulatory System:
○ Three-chambered heart (except crocodilians which have a four-chambered heart)
○ Ectothermic metabolism
Reproductive System:
○ Internal fertilization
○ Amniotic eggs with leathery shells or live birth in some species
Skeletal System:
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Strong, flexible backbone
Limbs adapted for crawling, climbing, or swimming
4. Adaptations
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Thermoregulation:
○ Behaviorally regulate body temperature by basking in the sun or seeking shade
Locomotion:
○ Variety of adaptations for crawling, climbing, swimming, and burrowing
Diet:
○ Carnivorous (e.g., snakes, crocodiles)
○ Herbivorous (e.g., some turtles, iguanas)
○ Omnivorous (e.g., some lizards)
5. Examples of Reptiles
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Turtles:
○ Green sea turtle: Marine species, herbivorous diet
○ Box turtle: Terrestrial, omnivorous diet
Lizards:
○ Komodo dragon: Largest lizard, carnivorous
○ Chameleon: Arboreal, insectivorous, color-changing abilities
Snakes:
○ King cobra: Venomous, longest venomous snake
○ Boa constrictor: Non-venomous, kills prey by constriction
Crocodilians:
○ American alligator: Found in the southeastern U.S., apex predator
○ Saltwater crocodile: Largest living reptile, found in brackish and saltwater
6. Conservation Status
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Many reptiles are endangered due to habitat destruction, climate change, pollution, and
illegal wildlife trade.
Conservation efforts include habitat protection, breeding programs, and legal protection.