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The Miracle That Is the Ostrich Egg

BY AWAKE! WRITER IN SOUTH AFRICA

MOTIONLESS in the incubator, the ostrich egg betrays nothing of what is happening inside or the dramatic display about to begin. Here on the ostrich farm, however, we have an opportunity to learn about the fascinating development of an ostrich, beginning with egg laying.

Pampering the Eggs

Mother ostrich lays her ivory-colored eggs, each weighing up to three pounds [1.45 kg], in a rudimentary nest in the sand.a Then, every day, workers transfer newly laid eggs to the farm’s incubators, which will be their home for about six weeks.

This is a time of pampering for the incubating eggs. They are kept warm and cozy at about 99 degrees Fahrenheit [37°C]—an ideal temperature for the new chicks to develop inside the shells. To prevent the yolk or embryo from settling at the bottom of the egg and sticking to the shell membrane, the farmer keeps the eggs in special trays in which they are turned automatically, or he has the eggs turned every day by hand. This imitates the way ostrich parents regularly turn the eggs in their sandy nursery in the veld.

A Peek Inside

How, though, can we know what is happening inside the eggshell? Gently picking up one of the eggs, the farmer places it in a hole in the top of a box that has a bright light bulb inside it. This procedure, known as candling, gives the farmer a shadowy glimpse of the remarkable developments inside the egg. Periodically, he candles the eggs to check on the progress of the life inside. If a few candlings show that the center of an egg remains fluid, it is evidently infertile and is not put back into the incubator.

During the 39 days that the ostrich egg spends in the incubator, miraculous growth takes place within the confines of the porcelainlike shell. At the same time, an air sac forms, which eventually takes up about one third of the available area inside the egg.b The unhatched chicks get quite cramped inside their shells and position themselves for their imminent escape. First, though, a crucial process has to take place—their yolk sac has to begin moving through their umbilical cord and navel into their tiny abdomen. This is vital because the yolk sac contains the nutrients and energy that they will shortly need as they make their break into the outside world.

Breaking Out of Their Shells

At last, the big day arrives, and we are here to see it. First, the little chicks have to break through the membrane into the air sac before they can get at the shell itself. Unlike other hatchlings that have an egg tooth to break their shell, ostriches have a protective layer that helps to shield the tip of their soft beak. Holding its shielded beak against the inside of the shell, the chick pushes the back of its neck against the membrane that separates it from the adjacent air sac. After much pushing and rubbing, this membrane eventually ruptures. Known as pipping, this enables the chick to occupy all the area inside the shell.—See diagram A.

The chick’s tiny lungs finally gasp their first breath of air! Its little lungs are now functioning. However, all the exertion makes it unbearably stuffy in the cramped confines of the egg. So the chick cannot give up now—it has to keep struggling and break through the shell itself. With all its might, the chick throws its head back repeatedly, hitting the tip of its beak against the inside of the shell. Suddenly, the exhausted little chick sees a glimmer of light as a tiny crack appears in the shell—and with it, the chick senses real fresh air!—See diagram B.

After a much-needed rest, the hatchling regains sufficient strength to continue cracking the fractured shell, making good use of its right foot and its tiny shielded beak. Then, heaving the cracked parts of the shell apart like a diminutive Goliath, the chick tries to sit up, blinking at the world outside with as much dignity and aplomb as a newly hatched, wobbly ostrich can summon.—See diagram C.

Why does the farmer not help the little chick out of its shattered shell? This is for the hatchling’s own sake. It takes some time for the egg yolk to be absorbed through the chick’s navel, which then contracts and closes up. A misguided helper trying to hasten the process can injure the fragile little creature or expose it to serious infection.

Anyway, at last the little fellows here at the farm are out of their shells. For us spectators, seeing the ostrich chicks emerging from a jumble of broken shells—exhausted but victorious—is a thrilling spectacle.

Meeting the Foster Parents

After a while the warm incubator air dries the chicks’ velvety down, and they become irresistibly cute and fluffy. Then they are put in a little pen out in the sun. How they seem to enjoy that! At last they can give their shaky little legs the exercise they have been yearning for.

The next day is a momentous one for the downy young birds. They are introduced to their foster parents—adult ostriches that will care for them for the next three months. Until now the little chicks have not felt hungry because they have been sustained by the nutrition from their egg yolk. Several days after hatching, however, they start to feel a bit peckish. But what can they eat? To our surprise, the chicks begin eating the fresh dung of their foster parents! This, the farmer explains, may help to boost their immature immune system.

Just look at the little tots frantically trying to keep up with the gigantic strides of their foster parents! It certainly takes a lot of effort. But ostrich chicks grow incredibly fast—an astounding 12 inches [30 cm] a month. So, amazingly, within just one month, they are able to keep up with the far-bigger adults.

When the young adolescents are six months old, they are fully grown and stand nearly eight feet [2.5 m] tall. It is hard to believe that just over seven months earlier, these lanky creatures—all neck and legs—were just motionless eggs in an ostrich-farm incubator.

[Footnotes]

[Diagram on page 23]

(For fully formatted text, see publication)

THE HATCHING PROCESS

A

B

C

[Credit Line]

Source of sketches: Dr. D. C. Deeming

[Picture on page 23]

The great day—chicks break out of their shells!

[Picture Credit Line on page 25]

John Dominis/Index Stock Photography