Frogs flaunt a range of traits and behaviors, many of which are similar to reptiles. These similarities have led many animal lovers to wonder if frogs are classified as reptiles or if they belong to another animal group.
Frogs are not reptiles but are amphibians that have a gill-breathing larval stage (water) and lung-breathing adult stage (land). Amphibians and reptiles have similarities but differ with regards to lifecycle stages, as well as physical, and behavioral characteristics.
Although reptiles and amphibians have some similar traits, there are many key differences in their overall makeup, development, and behaviors. Join us as we discuss why frogs are classified as amphibians and why they differ from animals belonging to the reptile group.
Why Are Frogs Not Reptiles?
Frogs are classified as amphibians as they hold the key traits belonging to the amphibian animal group (Tetrapoda). Most of the characteristics found in reptiles are not present in frogs, irrespective of the species or type. However, the two animal groups hold a few similar traits, which can become perplexing.
Scientists have compared countless animals over the years, grouping them based on inherent similarities and differences across species and genera. Frogs meet all of the described amphibian characteristics, whereas they lack most of the key traits held by reptile group members.
The general classification and taxonomy of frogs can be described as follows:
|Genus||Over 300 genera|
|Species||Over 7,400 species|
Animals must meet key requirements concerning lifecycles, bodily functions, and physical features to be classified as amphibians. The fundamental characteristics of all amphibians can be described as follows:
|Ectothermic||Frogs are cold-blooded, and they need to control their body temperatures using external influences.|
|Can live on land||Frogs transition to life on land as they mature, and they begin exploring terrestrial spaces during the froglet phase.|
|Can live in water||Frogs are fully aquatic during their early phases, and they can survive in water once they mature.|
|Tail present in larval phase||Tadpoles have tails which they use for swimming. These tails are absorbed by the body as they mature.|
|Smooth skin||Frogs have smooth and somewhat slimy skin, although some species may have textures upon the skin’s surface such as bumps and ridges.|
|Three-chambered heart||Frogs have a three-chambered heart, which differs from many other animal groups.|
|Aquatic reproduction||Most frog species reproduce through amplexus, using water bodies to support the process.|
|Has no neck||Frogs do not have necks capable of independent rotation.|
|Breathing through the skin||Frogs have permeable skin which they use for respiration.|
|Glands to keep skin moist||Frogs have glands across their bodies, which secrete substances to help keep their skin hydrated.|
Although frogs meet the typical amphibian requirements, they also flaunt a few traits that may or may not be observed in other members of the amphibian group. These additional traits further classify frogs as members of the Anuran order, whereas other amphibians may belong to different orders.
Amphibians vs. Reptiles
The primary traits that may become confusing involve some aspects of birth and bodily functions. Amphibians and reptiles are cold-blooded, and they typically begin their lifecycle as eggs. However, unlike reptiles, amphibians typically ‘transform’ from eggs rather than the ‘hatching’ process commonly observed throughout reptile species.
Both amphibians and reptiles belong to the same phylum and subphylum. Since amphibians and reptiles have a few similarities, they are often grouped together (Herpetofauna). However, they have far more differences than similarities, most of which can be identified at first glance.
Comparing Amphibians and Reptiles
Amphibians and reptiles may be closely grouped within the animal kingdom, but they are vastly different in many ways (CTNF). Their characteristics, distinct features, and infamous behaviors have been outlined in this summary of each group’s key traits:
|Distinct Features||Animals with a ‘dual-mode’ of existence, capable of exploiting aquatic and terrestrial habitats.||Creeping and crawling animals. Some species can survive underwater for specific time frames.|
|Skin||Smooth, moist, and permeable. Glands secrete sticky mucus to keep skin healthy and hydrated.||The skin is comprised of keratin and is covered in dry scales, typically arranged in patterns.|
|Toxicity Medium||Toxic amphibians have glands that secrete toxins throughout the skin’s surface. Only two known venomous species among over 7,400.||Reptiles have no glands on the skin, but they may be venomous.|
|Spawn||Amphibian eggs are jelly-like. They generally lay their eggs in water, but some species may lay eggs in moist terrestrial areas.||Reptile eggs are covered by a hard outer shell, which is leathery and calcareous in texture. They lay their eggs on land.|
|Respiration||Amphibians breathe through their skin through gas exchange. They use their skin in combination with their gills during the tadpole phase and their lungs once mature.||Reptiles cannot breathe through the skin and primarily use pulmonary respiration.|
|Limbs||Amphibians have four limbs with five digits, sometimes webbed, padded, or spaded. They have short forelimbs and long hindlimbs.||Most reptiles have four limbs except for crawling species such as snakes.|
|Heart||Amphibians have three-chambered hearts with two auricles and a ventricle.||Reptiles have three-chambered hearts with two auricles and a falsely divided ventricle. Only crocodiles have four-chambered hearts.|
|Eyes||Amphibians have bulging, bulbous eyes. They have a restricted color range, and they cannot differentiate between many colors. However, they have great vision.||Reptiles have a more advanced sense of visual depth and color.|
|Tongue||Some amphibians have a tongue that is bifurcated at the tip. However, most species have a complete tongue.||Reptiles typically have a tongue that is bifurcated at the tip, which is a classic reptilian characteristic.|
|Cranial Nerves||Amphibians have 10 pairs of cranial nerves.||Reptiles have 12 pairs of cranial nerves.|
|Nitrogenous Waste||Ammonia is the primary nitrogenous waste identified in amphibians.||Uric acid is the primary nitrogenous waste identified in reptiles.|
|Fertilization||Amphibians typically practice external fertilization. However, some species may practice internal fertilization.||Reptiles typically practice internal fertilization during reproduction.|
|Lifecycle||The lifecycle contains an aquatic larval form and a land-dwelling form upon maturity.||No aquatic larval phase is present with the reptilian lifecycle.|
Frogs may flaunt some similarities compared to many reptiles, but their unique features and distinct amphibian characteristics set them apart.
More About Frogs vs Reptiles
Frogs are incredibly diverse, and there are thousands of species belonging to the Anuran Amphibian group. While the described characteristics are common across all frogs, some species may have minor variations based on their genetics and environments.
Learn more about frogs vs reptiles and other animals on our blog: