Amphibians and reptiles both are cold-blooded vertebrates. However, there are key differences between them. The root of the differences is that amphibians spend part of their lives in water, while reptiles evolved to live on dry land. Here is a look at amphibians and reptiles, examples of each of them, and a summary of their differences.
- Amphibians spend part of their lives in water and part on land. Reptiles live on land.
- Juvenile amphibians have gills, while adults have lungs. Reptiles have lungs their entire lives.
- Most amphibians undergo metamorphosis to transition between water and land. Meanwhile, juvenile reptiles resemble adults.
- Amphibians have thin, damp skin, while reptiles have dry skin that is usually scaly.
- Most amphibians lay gelatinous eggs in water, while most reptiles lay leathery eggs on land.
Amphibians vs Reptiles Table of Differences
Here is a more comprehensive summary of the differences between amphibians and reptiles:
| Amphibians | Reptiles |
|---|---|
| Live on both land and water. | Mostly live on land. |
| Breathe through gills and lungs. | Breathe using lungs. |
| Most undergo metamorphosis, living in water as larvae and on land as adults. | Do not undergo metamorphosis. Larvae resemble adults. |
| Lay gelatinous eggs. | Lay leathery or hard-shelled eggs, although some give birth to live young. |
| Skin is porous, thin, moist, and usually smooth. | Skin is dry, hard, and usually scaly. |
| External or internal fertilization. | Internal fertilization. |
| Three-chambered heart. | Three-chambered heart, but ventricle has a septum (incomplete four-chambered heart). |
| Webbed feet for swimming. | Feet are adapted for both running and swimming. |
| Limited color vision. | More advanced color vision. |
| Less-developed brain with 10 pairs of cranial nerves. | More developed brain with 12 pairs of cranial nerves. |
| Excrete nitrogenous waste as ammonia. | Mostly excrete nitrogenous waste as uric acid. |
| Whole tongue that is often sticky. | Forked tongue that also serves as a sensory organ. |
| Usually can exchange gases through their skin. | Very little skin respiration. |
| Some secrete toxins through skin. | Can secrete toxins through nails and teeth. |
| Hiss or grunt. | Often have complex mating songs. |
What Is an Amphibian?
Amphibians (and reptiles) are cold-blooded vertebrates. This means their body temperature is close to the temperature of the environment and they have backbones with spinal cords. But, amphibians are tied to water, whether it be a river, pond, or just damp plants. Amphibians lay their jelly-like eggs in water. Fertilization occurs after the eggs are laid. The eggs hatch into larvae that have gills. For example, tadpoles are the larvae of frogs. In most species, the larvae undergo a metamorphosis into adults. They gain lungs and sometimes legs and spend more time on land. Amphibians have moist skin (no scales). They can breathe through their skin and may secrete toxins through it.
Here are examples of amphibians:
- Frogs (including toads)
- Salamanders (including newts and axolotls)
- Caecilians (less-familiar animals that resemble a snake or earthworm)
What Is a Reptile?
Reptiles complete their life cycle without water, even though some may live on or near it. Reptiles mate (internal fertilization) and most lay eggs. The eggs are either hard-shelled or leathery. The young are miniature versions of the adults, so there is no metamorphosis. Many reptiles have scales, but they all have dry, leathery skin.
Here are examples of reptiles:
- Turtles
- Tortoises
- Snakes
- Alligators
- Crocodiles
- Lizards
How to Tell Amphibians and Reptiles Apart
Telling amphibians and reptiles apart is not as easy as identifying whether or not it lives in water. Sometimes you have to take a closer look to distinguish between amphibians and reptiles. For example, a adult salamander and a lizard look a lot alike. Most of the time, the easiest way to tell them apart is by looking at their skin. Salamanders and other amphibians have thin, damp skin. Lizards have scaly or plated dry skin.
Turtles are another example. Many turtles spend almost all their time in the water. They even have the webbed feet associated with amphibians. However, turtles have hard, scaly skin. They breathe air at all stages of their lives. Turtles lay their eggs on land and their young look like tiny adults.
Which Came First?
Amphibians are older than reptiles. The first amphibians arose about 370 million years ago in the Devonian period from fish that resemble the lungfish and coelacanth. Reptiles, birds, and mammals (collectively called amniotes) trace their origins to ancestors that lived around 310 million years ago in the Carboniferous period.
Herpetology
Herpetology is the scientific study of amphibians and reptiles. The word herpetology comes from the Greek word herpetón, which means “creeping animal”. The study of amphibians is batrachology.
References
- Crump, Martha L. (2009). “Amphibian diversity and life history“. Amphibian Ecology and Conservation. A Handbook of Techniques: 3–20.
- Goodrich, E.S. (1916). “On the classification of the Reptilia”. Proceedings of the Royal Society of London B. 89 (615): 261–276. doi:10.1098/rspb.1916.0012
- Heatwole, H.; Carroll, R. L. (eds.). Amphibian Biology: Paleontology: The Evolutionary History of Amphibians. Vol. 4. Surrey Beatty & Sons. ISBN 978-0-949324-87-0.
- Sander, P. Martin (2012). “Reproduction in early amniotes”. Science. 337 (6096): 806–808. doi:10.1126/science.1224301
- Vitt, Laurie J.; Caldwell, Janalee P. (2013). Herpetology: An Introductory Biology of Amphibians and Reptiles. Academic Press. ISBN 978-0123869197.