Needed

1
Needed?

• Notes on oviparous etc.
• Scanned transparency diagram
• Picture of Bird w/eggs and nest
• Picture of Reptile w/eggs
• Development of a chick embryo pictures
• Bring out chick embryo specimens
• Alligator holding eggs in mouth

2
The Amniotic Egg

• Section 20-4

3
Invasion of the land.

• Amniotic eggs were an important adaptation to the
  survival of land animals.

4
Amniotic Egg

• The embryo develops in the amnion.
• Reptiles have a leathery shell.
• The embryo excretes waste into the allantois.
• The yolk is the main food supply for the embryo.
• Carbon dioxide and oxygen move freely through the
  shell.

5
6

• Amnion - encloses embryo in a protective pool of
  fluid.
• Allantois surrounds blood vessels and provides a
  place for waste.
• Chorion surrounds and protects everything.
• The yolk sac (unlabelled) surrounds the yolk.

6
7

• Shell - prevents water loss
• Albumin - protein that cushions the egg
• Amnion - provides a water environment
• Yolk - provides food internally for embryo
• Allantois - place for waste, respiration

7
Xerox 20-4

• 11 b
• 12 a
• 13 a
• 14 d

• 1 f
• 2 a
• 3 d
• 4 b
• 5 c
• 6 g
• 7 b
• 8 e
• 9 a
• 10 g

8
15
9
16

• Water...
• provides a solvent for waste
• A cushioning material for protection.
• A solvent for oxygen and carbon dioxide.