How are eggs made inside of a bird before they are laid, kept warm, and eventually hatch? The mother albatross in this clip from Sir David Attenborough’s Wonder of Eggs must eat enough to “amass a yolk so big that it can be transformed into a chick.”
Follow the egg’s biological development with an animation of the bird’s reproductive tract.
Mid-video, Attenborough also demonstrates how separate the protective calcium carbonate hard shell from its contents. He soaks an unfertilized quail egg in vinegar, revealing the soft inner membrane. Try this experiment.
“So now back inside the uterus, the egg is almost complete. Calcium carbonate, carried by blood vessels, is deposited on the soft egg membrane where it will harden and set forming the shell. Then other cells begin to discharge pigment like paint being squirted from hundreds of tiny paint guns as the egg slowly revolves yet more cells spray out spots and streaks.
“It’s taken just under 24 hours for the egg to be fertilized and enclosed within a hard shell, and now within the dark uterus, it waits like an actor in the wings ready to make its appearance on life’s stage. But which end will emerge first from the bird? Big end or little end?”
Related reading from AllAboutBirds.org: The Beauty and Biology of Egg Color.
Then watch these related eggshell videos, including:
• How Birds Get Oxygen Inside Their Eggs
• How does a chick hatch from an egg?
• The Field Museum’s amazing egg collection
• Observation of shell-less chick embryo development
• The Elephant Bird Egg and rare footage of young David Attenborough
And ICYMI: How to make bouncing eggs.
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