Difference Between Amphibians and Reptiles

The difference between amphibians and reptiles is mainly due to the differences in the properties like the existence of dual life cycle, type of fertilization and skin type. Both amphibians and reptiles are the animals belonging to the phylum “Chordata” and considered as “Cold-blooded animals”.

  • Life cycle: Amphibians have dual existence in their life cycle, whereby getting birth they adapt themselves to the aquatic habitat and by attaining maturity they live in the terrestrial habitat. In contrast to this, reptiles do not exist such dual life cycle.
  • Fertilization: The type of fertilization is external in amphibians whereas internal in reptiles.
  • Skin type: The amphibians have smooth and moist skin, whereas reptiles have hard and dry skin type.

In this context, we will discuss the key differences between the amphibians and reptiles along with the comparison chart. You will also get to know the definition and physiological characteristics of the two.

Content: Amphibians Vs Reptiles

  1. Comparison Chart
  2. Definition
  3. Key Differences
  4. Similarities
  5. Conclusion

Comparison Chart

PropertiesAmphibiansReptiles
Identifying featureThey have soft, smooth and moist skinThey have hard and dry with scutes and bony plates surrounding it
Dual existenceThese exhibit dual existence by living first in water during the larval stage and second by living in terrestrial habitat on maturityThese do not exhibit such property
ReproductionOviparous typeBoth oviparous and viviparous type
Fertilization typeExternalInternal
Scale presenceAbsentPresent
RespirationIt’s respiration can be through gills, lungs and skinIt’s respiration is mainly through lungs
Larval stage/MetamorphosisPresentAbsent
Longevity/Life spanComparatively lessMore
Defense mechanismBy nocturnal activity and aposematic colourationThrough Camouflage or by playing dead or retreats into the protective shell
WarningSecretes toxic substance like tetradotoxin and vile tasting through the skin Warn predators by releasing foul smell and toxins
Additional sensory organThese can sense water pressure changes through their lateral lineThey have vomeronasal organ, which releases chemical substance and also have thermoreceptors on their face to detect their prey in the dark
CirculationThrough three chambered heart which consists of two atria and one ventricleThrough three to four chambered heart which consists of two atria and one ventricle (subdivided into two aortas)
Neck vertebraSingle vertebra present on the neckMultiple vertebra present on the neck
Estimated number in earthMore than 8,000 amphibiansMore than 10,000 reptiles
ExamplesFrogs, toads, salamanders etc.Snakes, turtles, crocodiles, lizard etc.

Definition of Amphibians

Amphibians are the animals belonging to the phylum Chordata and class Amphibia and they are ectothermic with soft and moist skin. They exist dual modes in their life cycle, wherein the first phase, i.e. larval stage (they dwells in the aquatic habitat) and the second phase, i.e. maturity stage (they dwell in the terrestrial habitat).

For the blood circulation, amphibians have three-chambered heart, i.e. two atria and one ventricle in their circulatory system. Their nervous system consists of a central brain, spinal cord and nerves with a less developed brain. For the excretion, amphibians have two kidneys which primarily excrete uric acid from the cloacal vent. Let us discuss some morphological and physiological properties of the amphibians:

Metamorphosis: Amphibians show metamorphosis as a few of them go through a dual life cycle (larval and adult stage) in two different habitats (water and land). Metamorphosis is a distinguishing feature that differentiates amphibians from the reptiles. However. some amphibians do not show metamorphosis, i.e. they either live their life in terrestrial or aquatic habitats.

Respiration: The amphibians living in the aquatic environment have gills through which they respire in water. Majority of the amphibians living in the terrestrial habitat breathe through their well-developed lungs once they reach maturity. Few may also respirate through their moist skin by trapping oxygen from the surrounding, which then enters the skin’s blood vessels to the rest of the body.

Skin: Amphibians generally have moist skin so that they can carry out cutaneous respiration. Long exposure to sunlight may show devastating effects like the death of an organism, as the sun may absorb the moisture from their skin. Thus, amphibians prefer to live in a damp or moist environment. Their skin also plays an important role in the defence system, as brightly coloured amphibians warn their predators that they are noxious and a few secrete chemicals from the skin glands that can irritate the predators.

Nutrition and digestion: Amphibians have protruded and muscular tongue through which they can catch their prey. The prey then goes through the short oesophagus lined by cilia to the stomach by the help of mucus. The digestive enzyme chitinase present in the stomach helps in the digestion of chitinous cuticle of the prey.
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Definition of Reptiles

Reptiles are the animals belonging to the phylum Chordata and class Reptilia and they are ectothermic with hard and dry skin. They do not exhibit dual modes in their life cycle, and they can live in a variety of habitats. Shedding is another distinguishing property which makes reptiles different from the amphibians, as they go through ecdysis throughout their lifetime.

For the blood circulation, reptiles have a three to four-chambered heart with two atria and one ventricle (subdivided into two aortas). The nervous system includes a central nervous system, spinal cord and nerves. The excretion system includes three small kidneys, which mainly excretes uric acid as a nitrogenous waste. Let us discuss some morphological and physiological properties of the reptiles:

Metamorphosis: Reptiles do not undergo a metamorphosis during their life cycle, i.e. they lack larval stage, unlike amphibians. They appear as tiny replicas of their parents during the early stage.

Respiration: For the process of breathing, they have more efficient lungs than the amphibians that provide a larger surface area for the gaseous exchange. They can not respirate through their skin surface, as they have dry skin that does not allow gaseous exchange.

Skin: Reptiles can live in dryland as their skin is surrounded by the horny epidermis. Scales or scutes are also present on the exposed parts of the reptiles, which protects them from the direct heat. It lacks a thick dermal layer, unlike mammals. Through their dry skin, reptiles can not respirate, but they regulate the body temperature according to the changing environment.

Nutrition and digestion: Reptiles have different oral glands through which they can catch or immobilize their prey. The food then goes through the short oesophagus to the stomach by the peristaltic movement. The digestive enzymes and gastric juices in the stomach will breakdown the complex components of food like proteins. Finally, the gastrointestinal tract absorbs the nutrients from the food and the remaining waste goes out through the cloaca vent.

Key Differences Between Amphibians and Reptiles

  1. Amphibians have soft, smooth and moist skin, whereas reptiles have hard, dry and scaly skin.
  2. Amphibians exhibit dual existence as they first live in water during the larval stage and live in a terrestrial habitat on maturity, while reptiles do not exhibit such property.
  3. The reproduction is oviparous type in amphibians, whereas reptiles may exhibit both oviparous and viviparous types of reproduction. Oviparous animals produce eggs external to the environment, while viviparous animals give birth inside the womb and undergo embryonic development.
  4. Scales or bony plates are found on the body of the reptiles for the protection, whereas absent in amphibians.
  5. The respiration of amphibian can be through gills, lungs and skin, whereas reptiles breath solely through their lungs.
  6. The lifespan of amphibians is less compared to the life span of reptiles. For example, a turtle has 180 years of longevity, whereas American bullfrog has 8 years of longevity.
  7. In amphibians, the defence mechanism is through nocturnal activity and aposematic colouration. Reptiles defend themselves through camouflage or by playing dead or retreats into the protective shell.
  8. Amphibians secrete toxic substance like “Tetradotoxin” and vile tasting through their skin whereas reptiles warn predators by releasing foul smell and toxins.
  9. There are some additional sensory organs found in amphibians through which they can sense water pressure changes through their lateral line. In reptiles, vomeronasal organ is located on the top of mouth which releases chemical substance, and in addition to this, they also have thermoreceptors on their face to detect their prey even in the dark.

Similarities

  1. Amphibians and reptiles are cold-blooded animals.
  2. Both of them belongs to the phylum “Chordata” (possess central vertebral column).
  3. Skin colour alternation is the property, which is common in both types.
  4. Both have keen eye-sight, which helps them to feed on their prey by flicking their tongues.
  5. Both can autotomize (a process merely refers to the removal of a tail as a defensive response).

Conclusion

Therefore, amphibian and reptile are vertebrate animals, which are ectothermic or cold-blooded. Both of them share many differences and some similarities, which we have discussed in this content. We can distinguish both of them, based on scale presence and skin type. The examples of amphibians are frogs, salamanders, toads etc. which lacks scales on their body and having moist and soft skin. The examples of reptiles are turtles, snakes, crocodiles, lizards etc. whose body is protected by the presence of scales with hard and dry skin.

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