African penguins reproduce by laying eggs. The female penguin will lay two eggs about three to four days apart. Eggs are produced usually after three weeks of nest building and many successful occurrences of copulation. Post copulation, internal fertilization occurs. As the egg travels down the female reproductive tract it builds the albumen (egg white), yolk sac, yolk membrane, shell membrane and shell. The egg is then passed out through the female’s cloaca. The yolk sac is the main food supply for the developing embryo and includes protein, fat and minerals.-Pamela Schaller