What are amphibians?

What are amphibians? (Definition and examples)

Amphibian Life is here to sharing interesting facts and information about amphibians. But first, we need to understand what an amphibian actually is. Are we talking about frogs? Snakes? Reptiles? Fish? What are amphibians really? And what makes them different to other animals?

In this article, we define “amphibian”, we look at the characteristics of amphibians, and we share examples of amphibian creatures.

Amphibian definition

Amphibians are cold-blooded, vertebrate animals that have an aquatic phase of life (spent in water, breathing through gills) and a terrestrial phase of life (living on land, breathing with lungs).

  • Cold-blooded means that an amphibian can’t generate its own body heat. Instead, their temperature varies with the temperature of the surrounding environment.
  • Vertebrate means that amphibians are a type of animal with a backbone or spine.
  • Aquatic means in water. Amphibians begin their life living underwater, breathing through gills and swimming with tails.
  • Terrestrial means on land. At a later stage of life, amphibians develop lungs and legs and move out of the water to live on land.
What are amphibians? They are a group of animals that includes frogs
Frogs are a type of amphibian. Photo credit: Charles J Sharp / CC BY-SA

Probably the best known example of an amphibian is the frog. You probably know that frogs begin life as tadpoles: little fish-like creatures that breathe through gills and swim around with small tails. You’ll also know that frogs don’t stay tadpoles forever. They develop legs and eventually hop on to dry land, where they breathe through their lungs, like we do.

Characteristics of amphibians

Clearly, how amphibians look varies depending on the stage of their life. A tadpole looks completely different to a frog, for example. But there are some characteristics that are generally consistent across most amphibian species.

  • Amphibians have moist bodies. If you picked up a snake (which is not an amphibian) it would feel very dry. Contrary to popular belief, snakes aren’t “slimy”. However, if you picked up an amphibian – such as a frog – its skin would feel wet and slippery.
  • Amphibians don’t have scales. Taking the snake example again, if you looked closely at a snakes body, you’d see lots of tiny plates, called scales. Scales are what fish and reptiles have instead of skin. Amphibians don’t have scales, they have smooth skin.
  • Amphibians will die if their body dries out. The reason amphibians have moist bodies and smooth skin is that they need it to survive. Amphibian’s have a special skin that is able to absorb water and oxygen, stopping them from getting dehydrated. This is why, even once they start living on land, amphibians usually live close to water.
  • Some amphibians can “aestivate”. This is a special ability that allows certain types of amphibian to enter a dormant state if conditions become too hot and dry. They then return to normal once cooler, wet conditions return.
  • Some amphibians are poisonous. Poisonous amphibians release toxic chemicals through their skin to harm and scare away predators.
Amphibians can be identified by shared characteristics, such as moist bodies and a lack of scales.
Poison Dart Frogs are a poisonous type of amphibian. It’s not unusual for poisonous amphibians, and other poisonous animals, to be brightly colored to warn off predators.

Amphibians list

We often have people ask us to publish a list of all amphibians. We could… but it would be very long! There are over 8000 amphibian species.

We can, however, list some of the most well-known examples…

Amphibian examples

Amphibians fall into three categories:

  1. Frogs and toads
  2. Salamanders
  3. The less well-known, Caecilians.

Frogs and toads are amphibians that have long back legs, short front legs, webbed feet, no tails and large eyes. You may not know that the difference between a frog and a toad is that frogs have smooth skin, whereas toads have warty skin!

Frogs and toads are one of the three main groups of amphibians
A warty-skinned toad. Photo credit: Iric / CC BY-SA

Salamanders are a group of amphibians that share the characteristics of a long body, a tail and short limbs. Newts are a type of salamander.

Salamanders are one of the three main groups of amphibians
A black and yellow Fire Salamander. Photo credit: Cristo Vlahos / CC BY

Caecilians are fascinating creatures that many people have never even heard of! They look like snakes or worms, have no legs, and live in rivers and streams, where they burrow into the riverbed.

Caecilians are one of the three main groups of amphibians
Caecilians means “the blind ones” as their vision is limited to only being able to tell light from dark. Photo credit: Franco Andreone – see authorization / CC BY-SA

Remember: Frogs and toads, salamanders, and caecilians are groups of amphibians. Within these groups there are many different species.

For example, you may already know of different types of frog. There isn’t just one generic “frog”. There are frogs of all different shapes and sizes.

Amphibians vs Reptiles

Because they look kind of similar, people are often confused about the difference between amphibians and reptiles. Let’s clear up the confusion…

Reptiles are scaly creatures, with dry bodies, that live on land. They breathe through their lungs and don’t have gills. They lay eggs on land and the eggs have hard shells.

Are crocodiles amphibians? No, they are reptiles.
Are crocodiles and alligators amphibians? No. Both crocodiles and alligators are reptiles. They are not amphibians. Photo credit: Leigh Bedford / CC BY

As we’ve already learned, amphibians are very different to reptiles. They have smooth skin (no scales) and moist bodies. They live underwater and breathe through gills at one stage of their life, and live on land breathing through lungs at another stage. Amphibians lay eggs in water, not on land, and their eggs are soft, with no hard shell.

Are turtles amphibians?

One of the most common questions we get asked is whether turtles are reptiles or amphibians.

It makes sense that there’s some confusion, as turtles do spend some of their time in water and some time out of water. They’re also cold-blooded, like amphibians.

But turtles are not amphibians. There are a few key differences: turtles have scales and a shell, where amphibians don’t, and turtles lay eggs on land, not in water.

Turtles are actually reptiles, not amphibians.

Turtles are not amphibians. They are a type of reptile.
Are turtles reptiles or amphibians? Though they can be found underwater, turtles are reptiles, not amphibians. Photo credit: Brocken Inaglory / CC BY-SA