REPTILIA:
Adaptations of Amniotes:
Amniotic egg:
All amniotes have eggs with 4 extraembryonic membranes: the amnion, allantois, chorion and yolk sac
Amnion encloses the embryo in fluid, cushioning the embryo and providing an aqueous medium for growth
Metabolic wastes are stored in a sac formed by the allantois
The chorion surrounds the entire contents of the egg and is highly vascularised
The chorion and allantois form a
respiratory organ
Amniotic eggs are surrounded by a
mineralised flexible shell which
forms a mechanical support and
semipermeable barrier to allow
passage of gases while limiting
water loss
Yolk sac for nutrient storage
Thicker and more waterproof skin:
Thicker, keratinized skin that is less permeable to water
Keratin gives the skin protection and limits water loss
The epidermis contains a hard form of keratin called beta keratin
Rib ventilation of the lungs:
Amniote lungs are better developed than amphibians due to larger surface area
Draw air into lungs by expanding thoracic cavity using costal muscles or pulling
diaphragm or liver posterior
Stronger jaws:
Expansion of jaw musculature provided better mechanical advantage when seizing large prey
Their tongue is muscular and mobile
Adaptations of Amniotes:
Amniotic egg:
All amniotes have eggs with 4 extraembryonic membranes: the amnion, allantois, chorion and yolk sac
Amnion encloses the embryo in fluid, cushioning the embryo and providing an aqueous medium for growth
Metabolic wastes are stored in a sac formed by the allantois
The chorion surrounds the entire contents of the egg and is highly vascularised
The chorion and allantois form a
respiratory organ
Amniotic eggs are surrounded by a
mineralised flexible shell which
forms a mechanical support and
semipermeable barrier to allow
passage of gases while limiting
water loss
Yolk sac for nutrient storage
Thicker and more waterproof skin:
Thicker, keratinized skin that is less permeable to water
Keratin gives the skin protection and limits water loss
The epidermis contains a hard form of keratin called beta keratin
Rib ventilation of the lungs:
Amniote lungs are better developed than amphibians due to larger surface area
Draw air into lungs by expanding thoracic cavity using costal muscles or pulling
diaphragm or liver posterior
Stronger jaws:
Expansion of jaw musculature provided better mechanical advantage when seizing large prey
Their tongue is muscular and mobile
