Reptilia

What is Reptilia?

Class Reptilia comprise of vertebrates which are held to have evolved from amphibians. These animals belong to the phylum Chordata under animal taxonomy. 

There are some general characteristics of reptiles which can be found in almost all members of the class. It includes dry skin without any gland, cold-blood, and scales on their body, among others. Examples of reptiles are – lizard, turtle, snake, chameleon, crocodile etc. 

Read on to know more about the main characteristics of reptiles. 

Characteristics of Reptiles

While there can be variations in the general features of reptiles, there exist certain common characteristics. The unique features of reptiles have been mentioned below.

  • Reptiles are cold-blooded, also known as Ectothermic, and are mostly terrestrial

  • There are epidermal scales on the body of reptiles 

  • Their skull comprises of a single occipital condyle

  • Heart of reptiles usually includes two auricles which are separated by a ventricle. An exception is a crocodile with a four-chambered heart

  • There are 12 pairs of cranial nerves 

  • Barring snakes, ears of reptiles have 3 parts – internal, middle and external 

  • Cloaca is present in reptiles 

  • Reptiles are mostly oviparous. It lays eggs as opposed to giving birth to young ones. 

Fun Fact

Snakes and lizards are most common examples of reptile animals. Even though those have slits for nostrils, they use their tongue to smell. They flick out their tongue and pass it on to Jacobson’s Organ.  The chemicals that stick at their tongues impart smell. 

Reptilia Classification 

Reptilia can be further divided into Subclasses and Orders 

(1) Reptilia Sub-Classes

The different Reptilia subclasses are – Anapsida, Parapsida, Diapsida. The characteristics of reptiles under these subclasses are elucidated below. 

Anapsida 

  • Dermal bones provide sheath over skull

  • No temporal fossae

Examples – tortoise, turtle, terrapin

Parapsida 

  • Presence of a temporal fossa located at the anterior of skull

Note – Reptiles that belonged to this group went extinct in the Cretaceous period 

Diapsida 

  • Presence of two temporal fossae in the skull

  • The reptiles under this class are most diverse

Examples – Lizard, snake, crocodile

Note – Pterosaurs and dinosaurs also belonged to this class


There are certain groups which have gone extinct under class Reptilia. Those are – Cotylosauria, Ichthyopterygia, Archosauria, and Synaptosauria. Dinosaurs primarily belonged to these orders. 

Test Your Knowledge 

i. Among which types of reptiles, Typhlop belong?

(a) False snake 

(b) True snake

(c) Shark

(d) True worm 

ii. Most highly advanced feature of the Reptilia, crocodile is –

(a) Thecodont

(b) 4-chambered heart 

(c) Shelled eggs 

(d) Powerful jaws 

     [See the solutions to the quiz at the end of the article]

(2) Reptilia orders

The different Reptilia orders are – Chelonia, Rhyncocephalia, Squamata, Crocodilia. The characteristics of reptiles under these orders are indicated below.

Chelonia 

  • Body covered with a shell

  • There are two parts to the body shell – ventral plastron and dorsal carapace

  • The parts are attached by bridges between the hind and front legs

Examples – turtles, tortoise

Rhyncocephalia

  • Resembles lizards but dietary habits and habitations are different

  • Only two species alive in coast off New Zealand

Squamata

  • This order primarily comprises of lizards and snakes, but there are attributes that distinguish between two reptiles

  • Lizards have legs and eyelids, but that is not the case for snakes

Crocodilia 

  • Legs and feet are suitable for moving on both land and water

  • Tough flattened tail helps in swimming 

Examples – crocodile, gharial, caiman, alligator

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FAQ (Frequently Asked Questions)

1. What characteristics do reptiles have?

One of the major class reptilia characteristics is having vertebra. These are mostly oviparous, that is, lays eggs. Reptiles also have scales or scutes that form the dermis.

2. Name any two reptiles.

Snakes and lizards are common examples of Reptiles. This classification of reptiles shares the common features of movable quadrate bones and scales.

3. What animals are reptiles?

The members of class Reptilia, exhibiting characteristics of internal fertilisation, presence of vertebra, epidermal scales and amniotic development etc. are called reptiles. 

[Solutions]

i. (b) True snake 

ii. (b) 4-chambered heart