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
The Amniotic Egg Section 20-4
Invasion of the land…. • Amniotic eggs were an important adaptation to the survival of land animals.
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.
#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.
#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
1 f 2 a 3 d 4 b 5 c 6 g 7 b 8 e 9 a 10 g 11 b 12 a 13 a 14 d Xerox 20-4
#16 Water…... • provides a solvent for waste • A cushioning material for protection. • A solvent for oxygen and carbon dioxide.