Why are eggs oval and one end big and the other end small?

There are many commonplace but easily overlooked things in life, and you who are good at observation must have noticed them. For example, the eggs of all animals we see in daily life are oval-shaped, and these oval-shaped eggs are large at one end and small at the other.

Have you ever wondered why this is the case? Let’s talk about it today!

01. Why are the eggs of animals oval in shape?

The reason why animals' eggs are oval-shaped is a physics problem. There are three main reasons: surface tension and gravity (that is, the earth's gravity), air chambers, and squeezing.

1. Surface tension mainly explains why eggs are spherical rather than cubic. As for the last two, I don’t know which one is more important or whether there is a causal relationship.

I drew the whole process of egg development:

2. The principle of minimum energy . Due to the effect of surface tension, the surface energy of a water droplet should be as small as possible. Of course, anyone who has studied physics knows that the surface tension of a sphere is the smallest, so a water droplet is basically close to a sphere. Of course, the process of egg formation is similar.

3. The earth also has gravity , which makes it impossible for an egg to be absolutely spherical.

Of course, if you go to space, you might see spherical ones.

02. Why is one end big and the other end small?

As for why the egg is big at one end and small at the other, it has to do with the structure of the egg. As shown in the following figure:

The big head has a small chamber filled with air, called the air chamber.

The functions of this structure include:

1. Promote the development of chicks

2. Promote chicks to break out of their shells

3. In addition, there is a theory that this is related to the way eggs are produced.

When the egg is just formed, it is spherical. It passes through the tubes in the bird's body and is eventually expelled from the body. This expulsion process is driven by the contraction and squeezing of the bird's oviduct. The egg shell is soft at this stage. Therefore, continuous squeezing makes it become an ellipsoid, and this squeezing force acts on the back of the egg, so the egg presents a shape with one end large and the other end small.

I have my doubts about this theory, because there is evidence that the egg is already a hard-shelled egg 30 minutes before leaving the body. Squeezing does not affect the distribution of the egg. In fact, if the egg is completely soft before leaving the body (not an ovary or a newly developed egg), then a soft yolk plus a soft egg white will be pressed into a lump of egg water, and even if it is elastic, it will form a tube. (Imagine defecation)

03. Are there eggs in other shapes?

But, biology is the cure for all kinds of dissatisfaction, this is my motto.

Because there are eggs that are close to the standard ball:

Round eggs are extremely rare, with the chance of appearing as little as one in a billion.

"If a hen is frightened while laying eggs, the egg-laying time will be shortened, resulting in the production of round eggs." A livestock veterinary expert in Shouning County said that the main components of eggshells are phosphorus and calcium. When phosphorus and calcium combine to form the eggshell in the birth canal, if the process does not take enough time and the eggshell is not squeezed enough, it will become round.

Of course, if you ask, aren’t there other shapes of eggs?

Does this count? Cube

Recently, a chicken farm in South Korea made a bold attempt to use similar technology to implant specially made cubic components into the uterus of hens, causing the hens to lay the world's first square-shaped eggs. The technician said in an interview: "As long as the components are suitable, any shape can be cultivated." Netizens said: I want to know whether the chicks born will also be square.

Today's science popularization ends here. Now everyone understands why eggs are oval-shaped and have one end larger than the other, right? ——Follow Teacher Li and you won't get lost in science popularization!