What’s the Difference Between Reptiles and Amphibians?

Reptiles and amphibians are two creatures that are often interchanged wrongly.

Perhaps the difficulty people encounter while deciphering the difference between reptiles and amphibians is rooted in their many similarities and the fact that reptiles evolved from amphibians, as scientists have proved.

These animals share many characteristics, including their evolutionary history and vertebrate structure, belonging to the same phylum and sub-phylum, and being cold-blooded.

More so, both creatures can be found on every continent except Antarctica. Nevertheless, amphibians and reptiles possess features that distinguish them from each other.

The zoologist Josephus Nicolaus Laurenti first coined “Reptilia” for reptiles and identified them as a separate division from “Amphibia.”

Over time, evidence of their difference in many aspects has only become clearer.

Even though they belong to the same phylum chordate under the animal kingdom, they also belong to different classes in the animal kingdom.

An interesting aspect of these creatures is that their differences can be found in their similarities. Keep reading as we examine the differences between reptiles and amphibians. 

Difference between Reptiles and Amphibians 

1. Difference in their Name and Meaning 

As the introductory part of this article suggests, both amphibians and reptiles are cold-blooded vertebrate animals with distinctions in their names. 

The name “amphibia” is derived from the word amphibious, which roughly means a “double life,” i.e., it refers to the dual mode of existence of the members of the Class Amphibia to live both on land and in water. 

The animals in this class are divided into three orders: Caudate, which comprises salamanders and newts; Anura, which includes frogs and toads; and Apoda, which includes caecilians.  

On the other hand, the name “reptile” comes from the Latin word “repent,” which means “to crawl.” Crawling is one of the basic characteristics of animals in this class. 

Reptiles are also divided into four orders. The order Crocodilia includes crocodiles and alligators. Squamata comprises lizards and snakes. Sphenodonta includes taurates, and Testudines include turtles and tortoises.  

2. Difference in Niche Habitat 

A unique difference between reptiles and amphibians is their behavior toward their habitat.

Although reptiles and amphibians sometimes share the same habitats, they do not always fill the same niche. 

Amphibians live in both water and land, i.e., they survive well in and outside of water. 

Most amphibians will lay their eggs in water and spend part of their lifecycle there. i.e., they tend to spend their larval stage in aquatic environments but migrate to land in adulthood. An example is the frog. 

Many here will spend most of their time in or near the water, while some species spend their entire lives there.

One example is the olm, a salamander species that lives in freshwater limestone caves. 

On the other hand, reptiles are terrestrial. They tend to live on land, but some species, like turtles and crocodiles, may spend time in the water.

Nevertheless, most of the few that spend time in water do not have an aquatic stage in their life cycle. They end up nesting and resting on land. An example is the crocodile.  

Regarding niche habitat, while amphibians live in aquatic environments during their larval stage, reptiles do not lay eggs in water.

Even aquatic reptiles like turtles and crocodiles returns to land to lay their eggs.

3. Nature and Function of Their Skin

One noticeable physical difference between reptiles and amphibians is the nature and function of their skin. As we mentioned earlier, their differences are embedded in their similarities.

Both amphibians and reptiles shed their skin, but the structure and biology of their skin differ greatly. 

Amphibians have permeable, smooth, moist skins protected by a slippery secretion of mucus, which keeps them from drying out.

Their permeable skin here is also an adaptive measure, allowing them to breathe on land and in the water.

The skin also secretes toxins, which act as a defense mechanism against predators.

On the other hand, reptiles have dry, watertight skins made up of hard or soft scales.

The shape and size of scales differ according to species and are arranged in a particular pattern, which allows the reptiles to survive in harsh conditions. 

The impermeable scales of reptiles help protect them from other toxins and pollutants on land, water, and air that an amphibian may find difficult to absorb.

This accounts for why reptiles can live and even strive in salt water while amphibians cannot.  

Reptiles have scales, and their skin is dry. In contrast, amphibians do not have scales, and their skin is often wet with mucus, which keeps them from drying up.

4. Difference in Method of Breathing

Respiration, which is part of living things’ characteristics, is another way to distinguish between amphibians and reptiles.

The respiratory systems of these creatures vary greatly.

While amphibians can breathe through their lungs, skin, or gills, reptiles’ primary breathing method is through their lungs.

The respiratory system of amphibians developed this way because of its dual lifestyle on land and in water. 

Most amphibians breathe through their lungs and skins, while some, like tadpoles, have gills like fish that they use to breathe.

Some aquatic amphibians, like frogs, usually undergo metamorphosis during their lifecycle, which changes them from aquatic animals that breathe with their gills or lungs, depending on the species. 

Amphibians have permeable skin; hence, the few that do not have lungs only breathe through their skin.

Their skin has to stay wet to absorb oxygen, so they emit mucus to keep their skin moist.

In a nutshell, reptiles are born with lungs for respiration, while amphibians are born with gills and later go on to breathe through their skin or lungs. 

5. The Difference in Mode of Reproduction 

Another significant difference between reptiles and amphibians is the mode of reproduction.

Amphibians are oviparous and undergo an internal mode of fertilization, i.e., the embryos develop inside the mother’s womb but hatch outside the mother’s body.

Reptiles, on the other hand, exhibit an external mode of fertilization. While all types of amphibians are oviparous, the same cannot be said of reptiles.

Some species of reptiles are oviparous, and some are viviparous (produce live young). 

Amphibian eggs are usually laid in water and covered with a transparent gelatinous (jelly-like) coating.

While reptiles lay their eggs on land, they are covered with hard or leathery shells.  

Although reptiles and amphibians hatch from eggs, the eggs are quite different, as stated above. More so, their lifecycles and ways of entering the world differ. 

Amphibians have an aquatic larval form and must undergo metamorphosis to reach adulthood.

The physical appearance of the young hatchling may differ from the adult. For example, a tadpole develops into a frog. 

Reptiles, on the other hand, do not have an aquatic larva form in their lifecycle and do not transition to reach the adult stage.

Besides, the physical appearances of the young are usually miniature versions of their adult parent.

6. Difference in Sight / Vision 

Both reptiles and amphibians have eyes, which aid in their vision. However, this sense of sight operates differently.

Since amphibians evolved to live on land and water, their eyes can function equally well above or below water. 

However, their eyes can only visualize a limited range of colors. Amphibians cannot distinguish between colors because their vision is restricted to a narrow band of the color spectrum.

However, reptiles’ eyes tend to be well-developed, with a more advanced sense of color and visual depth.

Reptiles have various color spectrums and can visualize and distinguish different colors.

7. Difference in Appendages and Defense Mechanism

The way these creatures defend themselves and the nature of their limbs are also noteworthy differences between reptiles and amphibians.

Most amphibians have short forelimbs and long hind limbs with webbed digits, so their primary modes of movement are swimming and jumping. 

In contrast, reptiles have more extensive forms of movement, which varies by species. Their limbs aid them in running and swimming.

Some walk slowly, jump, and climb, while others, like snakes, have no limbs and crawl. 

Like most animals, amphibians and reptiles also have adaptive features that help them defend themselves from predators.

Amphibians defend themselves by secreting toxins through their skin. 

In comparison, reptiles have hard scales over their body, which physically protects them. They also produce toxins from their teeth and nails to ward off predators.

8. Difference in Nervous System 

The complexity of the nervous system in amphibians is different from that of reptiles.

Amphibians have a less well-developed brain, with a smaller cerebrum and cerebellum than reptiles. They also possess only ten pairs of cranial nerves.

In contrast, reptiles have more developed brains with larger cerebrum and cerebellum.

Unlike amphibians, they possess 12 pairs of cranial nerves like other higher vertebrates such as mammals. 

More so, both creatures have a three-chambered heart, but amphibians have two auricles and a ventricle.

Reptiles have two auricles, while the ventricle is further divided through a septum. The exception here is the crocodiles, which have a four-chambered heart.