Amniotes

Overview of Amniotes

Amniotic Egg

• Named for the Amniotic egg
• Four specialized extraembryonic membranes
• Amnion: compartment of fluid that surrounds embryo
• Also protects embryo from physical damage
• Chorion, Yolk Sack, Allantolis: help in gas exchange, nutrients and waste storage
• Embryos no longer needed aquatic habitat to develop
• Similar to seed evolution in plants
• Early eggs had shells
• Lost in many other species
• Use rib cage to ventilate lungs
• More efficient than amphibians
• Loss of gas exchange through the skin