Reptiles

Explain about Reptiles.

CLASS REPTILIA:

Reptiles are adapted for complete existence on land in contrast to amphibians that are still tied more or less to water or moist habitat this indicates that reptiles have certain adaptations not found in amphibians some of these advancements shown by reptiles are their:

Characteristics Features:

(i) Reptiles have developed some sort of copulatory organs (penis like) necessary for internal fertilization.

(ii) In amniotic eggs of reptiles the shell is leathery which can resists dryness and injury. They have large yolky eggs.

(iii) Reptiles have dry scaly skin which is adapted to land life.

(iv) Reptiles have protective embryonic membranes aminion, allantois, and chorion.

(v) In reptiles the ventricle of heart is in completely partitioned ensuring more oxygen supply through blood circulation to all parts of the body.

In crocodiles, ventricle is completely partitioned into two.

(vi) Most reptiles have better developed limbs well adapted for efficient locomotion.

(vii) Reptile like amphibians are cold blooded (Poikilotherm) and hibernate in winter.

The above characteristic are for terrestrial habitat in which the reptiles mostly live.

However it is determined fact that reptiles have evolved from amphibians by undergoing the above changes and have become fully terrestrial.

• Reptiles flourished throughout Mesozoic period (225-65 million years).

• The climate which had been suitable for reptiles in that period, became less favourable to them in tertiary period.

• So most of them became extinct.

• The existing reptiles belong to four, out of a dozen or more main lines that have existed.

(i) Lizards and Snakes:

The present day repltles are, the lizards and snklaes.

(ii) Tuatara:

Secondly the tuatara (sphenodon) of New Zealand, which have survived up to today with little change.

(iii) Crocodiles:

Thirdly the Crocodiles are an offshoot from the stock from which modern birds were derived.

The reptiles of today have been derived from dinosaurs of Jurassic (195-136 million years), and cretaceous period (136-65 million years).

The modern reptile for the most part live in the temperate and tropical zone, indeed they fourish only in the latter.