What is the difference between a reptile and an amphibian?

While they might both look like 'scaly' or 'slimy' creatures found in the wild, reptiles and amphibians belong to two distinct classes of animals. Understanding the difference is not just a matter of biology, but also of precise vocabulary.

1. The Skin Factor

The easiest way to tell them apart is by touch (though maybe don't touch them in the wild!):

• Reptiles have dry, scaly skin. These scales are made of keratin (the same stuff as your fingernails) and help retain moisture, allowing them to live in very dry environments.
• Amphibians have moist, permeable skin. They don't have scales. Their skin often secretes mucus to stay damp, as many amphibians actually breathe through their skin!

2. The Life Cycle (Metamorphosis)

• Amphibians lead a 'double life' (the literal meaning of their name). They usually start life in the water with gills (like tadpoles) and undergo metamorphosis to develop lungs and legs for life on land.
• Reptiles are born as miniature versions of their parents. They breathe air from the moment they hatch and do not go through a larval stage.

3. The Eggs

• Reptile eggs have a leathery or hard shell. They are laid on land. The shell protects the embryo from drying out.
• Amphibian eggs are soft, jelly-like, and translucent. They lack a hard shell, which is why they must be laid in water or very damp places to survive.

4. Comparison Table

Feature	Reptiles	Amphibians
Examples	Snakes, Lizards, Turtles, Crocodiles	Frogs, Toads, Salamanders, Newts
Skin	Dry, scaly	Moist, smooth/bumpy
Breathing	Lungs only	Gills (young), Lungs & Skin (adults)
Habitat	Land and Water	Water and Land (must stay near water)

Linguistic Tip: Etymology

• Reptile comes from the Latin reptilis, meaning 'creeping' or 'crawling.'
• Amphibian comes from the Greek amphibios, where amphi means 'both' and bios means 'life'—referring to their dual existence in water and on land.

Common Confusion: The 'Cold-Blooded' Myth

Both are ectothermic (cold-blooded), meaning they rely on external heat sources to regulate body temperature. This similarity is often why people confuse the two groups, but as we've seen, their biology and life cycles are worlds apart!