General Characteristics Reptiles General Characteristics

Classification Phylum Chordata Subphylum Vertebrata - Class Reptilia Order Squamata- Lizards & Snakes Order Testudine- Turtles & Tortoises Order Crocodilia- Crocodiles & Alligators

Order Squamata

Order Testudine

Order Crocodilia

Herpetology The field of science that studies reptiles and amphibians.

Skin Dry thick skin covered with scales; Scales are part of the skin- all connected Scales provide protection from water loss and protection from predators. Scales are made of keratin Keratin is protein in the epidermis, often modified into nails, horns, and hair

Skin cont… Skin consists of 2 layers Epidermis- thin layer, and shed periodically Dermis- Thicker layer, contains chromatophores which give reptiles their color

Appendages Paired limbs Usually 5 toes with claws Limbs located under body provides more support for walking and running on land. Limbs absent in snakes and some lizards.

Respiration All reptiles breathe through Lungs.

Circulation Most reptiles have 3 chambered hearts. Crocodiles have a 4 chambered heart that enables more oxygen to reach body tissues.

Ectothermic All reptiles are ectothermic. Do not inhabit extremely cold regions. Live in temperate, tropical and desert climates.

Reproduction Reptiles do not need water to reproduce. Separate Sexes Internal Fertilization Most lay leathery or calcareous eggs, with the embryo developing after the egg is laid Young look like small adults Most do not provide parental care.

The Amniotic Egg The evolution of the amniotic egg was the adaptation that freed reptiles from dependence on water for reproduction. Amniotic Egg is a shelled egg that contains food and protective membranes for supporting embryonic development.

Parts of the Amniotic Egg 1. amnion- cushions; prevents dehydration 2. outer shell- protection 3. allantois- waste sac 4. yolk- food supply 5. albumin- additional food 6. chorion- gas exchange