(ii) Class - Reptilia

  • Class Reptilia includes a diverse group of vertebrates, commonly known as reptiles.
  • This group comprises animals like lizards, snakes, turtles, crocodiles, and birds.
  • They are ectothermic, meaning their body temperature is regulated by external sources.


General Characteristics:

  • Reptiles have dry, scaly skin, which helps prevent water loss.
  • They possess a well-developed, bony endoskeleton.
  • Limbs, when present, are typically pentadactyl (having five digits).
  • Reptiles exhibit a wide range of body forms, from elongated snakes to quadrupedal lizards and turtles.



  • Reptiles respire primarily through lungs.
  • They lack gills, and respiration is exclusively pulmonary.
  •  Some reptiles, like turtles, can respire through specialised structures, such as cloaca or buccopharyngeal cavity.


Feeding Habits:

  • Reptiles exhibit diverse feeding habits.
  • Most reptiles are carnivorous, feeding on insects, small mammals, birds, or other reptiles.
  • Some reptiles, like turtles, are herbivorous, feeding on plants and algae.


Circulatory System:

  • Reptiles have a three-chambered heart, except for crocodiles and some monitor lizards, which possess a four-chambered heart.
  • The heart pumps oxygenated blood to the body and deoxygenated blood to the lungs.
  • The partial division of the ventricle helps reduce the mixing of oxygenated and deoxygenated blood.



  • Reptiles excrete nitrogenous wastes primarily in the form of uric acid.
  • They possess well-developed kidneys that aid in water conservation.



  • Reptiles exhibit diverse modes of reproduction, including oviparity (laying eggs) and viviparity (giving birth to live young).
  • Most reptiles lay eggs with leathery shells, which are often buried in soil or sand.
  • Some reptiles, like certain species of snakes and lizards, exhibit ovoviviparity, where eggs hatch internally, and young are born alive.


Economic Importance:

  • Reptiles have ecological importance as predators and prey in various ecosystems.
  • Some reptiles, like crocodiles and alligators, are farmed for their skin, which is used in the leather industry.
  • Certain species, like turtles and snakes, are also kept as pets or used for research purposes.



  • Lizard (multiple species, e.g., Calotes, Hemidactylus)
  • Snake (multiple species, e.g., Naja, Python)
  • Turtle (multiple species, e.g., Chitra, Eretmochelys)
  • Crocodile (multiple species, e.g., Crocodylus porosus)
  • Tortoise (multiple species, e.g., Testudo, Geochelone)
  • Monitor lizard (multiple species, e.g., Varanus bengalensis)
  • Skink (multiple species, e.g., Mabuya carinata)
  • Gharial (Gavialis gangeticus).