Biology / Unit 10 Bio 2297 short lesson, about 20 seconds
Reptile Traits: the Amniotic Egg
Captions available
The idea
Reptiles lay an amniotic egg, whose internal membranes and shell let the embryo develop away from standing water, unlike amphibians.
In practice
A turtle's leathery-shelled egg retains moisture and exchanges gas through its shell while developing on dry land.
Where people slip
Students often assume the shell seals the embryo off entirely — it must stay gas-permeable for oxygen and carbon dioxide exchange.
Your place on the trail
Every lesson rests on earlier ones and opens later ones. Tap any to jump.
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