The class Reptilia is named after the Greek word rep meaning chest walking. Reptilia means reptiles. They walk with their chest full. The Mesozoic era of 16 and a half million years ago is called the Age of Reptiles. Their number of species is 9,831. 3 classes, 25 tribes and 167 species have been identified in Bangladesh.
Features of Reptilia
1. The body is dry and composed of scales or hard plates arising from the epidermis.
2. Each foot has 5 clawed toes.
3. Their body is divided into three parts. Head, neck and body.
4. The ventricles of their heart are incompletely bifurcated (except in crocodiles).
5. They are ectothermic land animals. That is, their body temperature changes with the rise and fall of the environment temperature.
6. They are cold blooded animals. So it goes into hibernation in winter.
7. They walk on the chest.
8. Their number of carotid nerves is 12 pairs or 24.
9. They lay eggs. ie Oviporous. Eggs are covered with a leathery calcareous shell.
10. The crown of the head is connected to the spinal cord by an occipital condyle.
11. Retractable holes are located transversely.
12. Four extra-embryonic membranes (amnion, chorion, yolk sac, allantois) are formed during the development of the embryo.
13. They are unisexual animals. Fertilization occurs. Muscular male sexual organs exist. Dr. Siddique Publications
14. They have no larval stage.
[key words to remember characteristics: epidermis, hard plate, finger, heart, ectothermic, hibernation, thoracic mass, cranial nerve, ovipore, occipital condyle, excretory pore, copulatory organ, larva]
Some animals of the class Reptilia
Lizard- Hemidactylus frenatus
Flying lizard – Chameleon vulgaris
Tortoise – Trionyx gangeticus
Sea turtle – Caretta caretta
Takshak – Gekko gecko
Gharial – Gavialis gangeticus
Gokhra snake – Naja naja
Guisap – Varanus komodoensis
Chameleon – Calotes versicolor
Crocodile – Crocodylus porosus
Fresh water crocodile – Crocodylus palustris