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Reptiles Vs. Amphibians

 
By Nick A. Romero, Biologist and environmental educator. November 10, 2021
Reptiles Vs. Amphibians

Reptiles and amphibians belong to the group of vertebrate animals, more specifically, tetrapod animals. Tetrapod is a term to describe animals that use four limbs to move or to manipulate things. Reptiles were the first truly terrestrial vertebrates, while amphibians are a group with transient traits between fish and reptiles. While some amphibians have managed to conquer the land, most still depend on water and need to stay close to it.

In this AnimalWised article, we want to introduce you to the main differences between reptiles vs. amphibians. You will also learn about the main features of each of these groups in terms of their physical appearance, reproductive processes, habitat and more.

You may also be interested in: Frog Vs. Toad - What is the Difference?

Classification of reptiles vs. amphibians

There is not an absolute nor invariable method for classifying animals. New scientific findings have allowed us to establish changes in the taxonomic location of groups and species. There are currently two methods for classifying animals: the traditional Linnaean classification and the Cladistic classification, which is the most current of the two.

Reptiles

This is how reptiles are classified according to the Linnaean classification:

  • Order Testudines: tortoises.
  • Order Squamous: snakes, blind shingles, and lizards.
  • Order Sphenodonts: tuataras.
  • Order Crocodilians: crocodiles.

The Cladistic classification establishes an organization based on evolutionary relationships and does not use the term reptiles. Instead, this method groups them as follows:

  • Lepidosaurs: Sphenodon (tuátaras) and Squamata (lizards, blind shingles, and snakes).
  • Archosaurs: crocodiles and birds.
  • Testudines: turtles.
  • Amphibians

Amphibians

In the case of amphibians, there are not so many divergences regarding their classification because there are some general agreements regarding their taxonomy. Other classifying criteria, such as their order and clade, will vary depending on the classification approach that is being used. Generally, amphibians are classified as follows:

  • Gimnofiones: caecilians.
  • Caudata (urodelos): salamanders and newts.
  • Anura (salientia): frogs and toads.

If you are interested in learning more about other methods for classifying animals, keep reading this AnimalWised article about the 5 Kingdom system of classification.

Reptiles Vs. Amphibians - Classification of reptiles vs. amphibians

Physical characteristics of reptiles vs. amphibians

Next, we are going to describe the main physical characteristics of the two groups in order to understand their differences:

Main physical characteristics of reptiles:

  • Their body is variable, in some is compact and in others is elongated.

  • Their body is covered with scales. In certain groups, they present epidermal bony plates and very few glands.

  • Their limbs have five fingers and are adapted for running, climbing, or swimming. In some cases, they do not have extremities.

  • Their body is well-defined with a developed bone formation. Most reptiles have a sternum and a rib cage.

  • They feature chromatophores which allow them to display a variety of colors.

  • They have teeth and their jaw is well developed and capable of generating a great pressure force.

Main physical characteristics of amphibians:

  • Their bodies are mainly bony skeleton, variable vertebrae, and in some cases, there have ribs.

  • The shape of their body is variable. Some have a well-differentiated head, neck, trunk, and extremities. Others are rather compact, with fused head and trunk and no neck definition.

  • Some amphibians lack limbs, which means they are apodal, while others have four distinct limbs. There are also some that have two pairs of small limbs that they do not use.

  • Usually, their feet are webbed and without nails. Depending on the group, they can have five, four, or even fewer fingers.

  • They also have chromatophores that offer a variety of colors, as well as various glands that in some cases are poisonous.

  • Their skin is smooth, moist, and practically devoid of scales. There are some cases that have scales that are immersed in the skin.

  • They usually have large mouths and teeth. Sometimes the teeth are found on both sides of the jaw but sometimes only on the upper side.

If you want to know more, take a look at our AnimalWised article on animals that change color.

Reptiles Vs. Amphibians - Physical characteristics of reptiles vs. amphibians

How do reptiles and amphibians reproduce?

Some of the main differences between amphibians and reptiles have to do with their reproductive processes, which are as follows:

Reproduction of reptiles

Most reptiles have separate sexes have and reproduce through internal fertilization. Males have paired testes that produce sperm that reaches the copulatory organ called the cloaca. Females have a pair of ovaries with oviducts that are responsible for producing nutritive substances for the embryo and the protective shell of their eggs. Reptiles evolved to lay eggs on the ground and in dry areas because the shell has internal membranes that provide protection and nutrition. Most newborn reptiles are born as pulmonates and do not require water.

Reproduction of amphibians

Amphibians have separate sexes and reproduce through internal or external fertilization. In the group of salamanders and caecilians, fertilization is internal. In toads and frogs, fertilization is external and the oviparous form of reproduction predominates. However, there are some ovoviviparous and viviparous cases.

Most amphibians require a body of water in order to lay their eggs. There are some cases that don't require water, but they still need a humid environment. Normally, they use leaves with accumulated water or dig holes on the ground to maintain appropriate temperatures. In some cases, frogs lay their eggs on land and later bring them water to keep them hydrated.

Keep reading this other AnimalWised article if you wish to know more about viviparous animals.

Development of reptiles vs. amphibians

One of the most important differences between reptiles and amphibians has to do with the way in which they develop and the changes in their physical appearance as they reach their adult state.

In the case of reptiles, there are no visible differences between newborns and adults apart from their size.

On the other hand, almost all groups of amphibians undergo an extreme metamorphosis. This means that there is a well-marked transformation between the larval and the adult form. There are certain exceptions to this rule, as is the case of axolotls. The larval traits of these animals are maintained in the adult form and this is known as neoteny. There are also certain terrestrial species of salamanders, whose appearance hardly changes as they develop.

Diet of reptiles vs. amphibians

Reptiles and amphibians have different diets and ways of feeding.

  • Reptiles have developed a much stronger bite in comparison to amphibians. This means that reptiles have stronger teeth. In terms of their diet, reptiles are either herbivorous or carnivorous. Iguanas, for example, are herbivorous while crocodiles are carnivores.
  • Amphibians are mostly carnivores although in some cases, their larval forms consume plant matter.

In both groups, there are species that have fleshy and extensible tongues that allow them to catch their prey.

Don't miss out on these articles if you wish to know more about carnivorous and herbivorous animals.

Habitat of reptiles vs. amphibians

Both reptiles and amphibians are widely distributed across the globe but their habitats are slightly different.

  • Reptiles are more likely to develop in terrestrial habitats. Some live in arboreal habits and some stay in the water even though they breathe on the surface.

  • Amphibians are an intermediate group between fish and reptiles. This means that they require aquatic habitats or, at least, high levels of humidity. Some amphibians spend their entire lives in the water while some transit between the two environments. There are some cases of amphibians that remain buried underground but they still need to be close to the water to survive.

How to tell the difference between reptiles and amphibians?

So far we have seen the main differences between reptiles and amphibians in terms of their physical appearance, their reproductive processes, their habitats, and their diet. Let's narrow all those differences into three easily distinguishable characteristics:

  • Skin: reptiles are covered in scales, which makes their skin appear dryer, harder, and thicker. In the case of amphibians, there is no presence of scales and their skin is soft and moist.
  • Eggs: Reptiles lay eggs with shells if they are oviparous, while amphibians lay eggs in jelly-like masses without a protective shell.
  • Metamorphosis: reptiles develop into their adult state without significant changes in their appearance while most amphibians undergo an extreme metamorphosis as they develop.
Reptiles Vs. Amphibians - How to tell the difference between reptiles and amphibians?

Examples of reptiles and amphibians

Both reptiles and amphibians are two very diverse groups of animals that incorporate thousands of different species. Here are some examples of reptiles and amphibians:

Examples of reptiles

  • Green sea turtle (Chelonia mydas)
  • Hermann's tortoise (Testudo hermanni)
  • Indian cobra (Naja naja)
  • Green Anaconda (Eunectes murinus)
  • Tuátara (Sphenodon punctatus)
  • Green Iguana (Iguana iguana)
  • Mexican blind lizard (Anelytropsis papillosus)
  • Draco spilonotus (Draco spilonotus)
  • Komodo Dragon (Varanus komodoensis)
  • Orinoco crocodile (Crocodylus intermedius)

Examples of amphibians

  • Fire salamander (Salamandra salamandra)
  • Alpine newt (Ichthyosaura alpestris)
  • Axolotl (Ambystoma mexicanum)
  • Greater siren (Siren lacertina)
  • Ringed caecilian (Siphonops annulatus)
  • Common toad (Bufo bufo)
  • Golden poison Frog (Phyllobates terribilis)
  • Madagascar tomato frog (Dyscophus antongilii)

If you want to read similar articles to Reptiles Vs. Amphibians, we recommend you visit our Facts about the animal kingdom category.

Bibliography
  • Hickman, C., Roberts, L. and Parson, A. (2000). Comprehensive principles of zoology. McGraw Hill Interamericana.
  • European Fauna Secretariat (2021). European Fauna.Available in:https://fauna-eu.org/cdm_dataportal/taxon/a8e97b2e-2734-49da-bebc-1fc0481b557c

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