15 Incredible Facts About Semen and Ejaculation

8 min read
15 Incredible Facts About Semen and Ejaculation

Sperm - the male reproductive cell - tends to be something most guys take for granted. In fact, depending on a person's sex life and masturbation habits, it's often something that's carefully collected in a tissue and immediately disposed of.

Despite this, sperm, semen, and even the process of ejaculation are nothing short of incredible. In the following 15 facts, we'll take a more detailed look at the incredible biological science behind semen, sperm production, and the inner workings of the male reproductive organs.

Men continuously produce sperm through a process called spermatogenesis, which occurs in the seminiferous tubules of the testes. This process starts at puberty and goes on throughout a man's life, producing millions of sperm each day.

Diagram of the Spermatogenesis



This production continues even if the person doesn't orgasm and ejaculate. The body has natural mechanisms that reabsorb unused sperm - making sure it's always the healthiest cells that are ready for potential fertilization.

1. Sperm is not the same as semen

Although the terms "sperm" and "semen" tend to be used interchangeably, the two things are actually quite different. Human spermatozoa (usually shortened to just "sperm") is the name of male reproductive cells (or "gemate") that are responsible for fertilization, whereas semen (also known as "seminal plasma") is the vehicle used to transport the sperm cells through the female reproductive tract.

Although the terms "sperm" and "semen" tend to be used interchangeably, the two things are actually quite different.

The interchangeable nature of the words is largely down to the fact that most medical professionals will use the term "semen" to describe the combination of semen and sperm.

2. Sperm measure around 0.002 inches

Sperm cells are extremely small - with studies suggesting they measure just 50 micrometers (0.05 millimeters) in length - which is roughly 0.002 inches.

Struggling to imagine what two-thousandths of an inch compares to? It's roughly half the thickness of a standard piece of printer paper or half the size of a fine grain of sand - and totally invisible to the naked eye.

3. Ejaculate can contain between 40 million to 750 million sperm

The average ejaculation contains between 20 million to 150 million sperms cells per milliliter. With a typical volume of between 2 to 5 milliliters, this means it's common for a single ejaculation to contain between 40 million and 750 million sperm cells.

4. Men may produce over 1 trillion sperms in a lifetime

Although numbers vary based on lots of different factors, it's perfectly possible for a man to produce well over 1 trillion sperm cells in his lifetime - and possibly much more.

Although studies vary, typically, a man will produce 70 million sperm cells each day. Since the sexually mature period of a person's life is roughly 50 years (from late adolescence into later life) - that means multiplying 70 million by around 18,250 days - giving an incredible figure of 1,277,500,000,000 (that's over 1.27 trillion). Since sperm count varies, it's hard to put a definite figure on this - but for context, it's a figure even close to this would be similar to somewhere around 3x the number of stars in the Milky Way galaxy.

5. Semen consistency can change day-to-day

There are many factors that can influence the consistency of semen - including hydration levels, diet, frequency of ejaculation, and a person's overall health.

Since these factors can change on a day-to-day basis, so too can the thickness of semen that's produced.

Frequent ejaculation can lead to thinner semen, as the seminal vesicles and the prostate may have less time to build up the fluids that contribute to semen's volume and consistency. On the other hand, more time between ejaculations can result in thicker semen. Proper hydration is also crucial, as dehydration can lead to thicker semen. Variations in consistency are generally normal but usually reflect changes in health or lifestyle.

6. A man could ejaculate over 60 liters of sperm in a lifetime

Based on the previously mentioned figure of around 2-5ml of semen being a typical amount ejaculated each time a man orgasms and the generalization that a man will be sexually active for around 50 years, this means that were a man to ejaculate close to daily, they would produce over 60 liters of semen in their lifetime.

Of course, this depends on sexual activity levels - but if these figures were even close to accurate for an individual, that would make enough semen to fill a typical bathtub over the course of a person's life.

7. Sperm can survive in a woman’s body for between 2-5 days

When sperm is ejaculated into the vagina, the odds appear to be stacked against its survival. The environment created by the female reproductive organs presents a number of challenges - including an acidic vaginal pH level and an immune response  from the cervix and uterus that considers sperm to be a foreign body.

Despite this, science suggests sperm can survive inside the female body for up to five days.

Despite this, science suggests sperm can survive inside the female body for up to five days. They will strategically swim when the conditions are most favorable, and use cervical mucus (which is more likely to be present in the ovulatory phase of the menstrual cycle) as a vehicle to further its journey safely.

8. Testicles keep the sperm cool

Unlike the female reproductive system - which is largely internal - the male sex organs are mostly found outside the body, and the reason is down to temperature. Human sperm production requires a temperature around 3.6 to 7.6 degrees Fahrenheit lower than the typical body temperature of 98.6 degrees Fahrenheit (37 degrees Celsius).

This is why the testicles are located outside the main body cavity, within the scrotum, which automatically acts as a "thermoregulator" - adjusting the distance of the testicles from the body to manage their temperature. If you're cold, your scrotum is likely to contract closer to the body - whereas if you're warm, it will hang lower, allowing the testicles to cool down.

9. Your lifestyle will affect the way your semen taste

Different foods and drinks can have a big influence on the way semen tastes. Fruits (such as pineapples, oranges, and papayas), some vegetables, and plenty of water is believed to result in sweeter tasting semen - whereas foods with strong odors, spicy foods, alcohol, caffeine, and smoking are thought to potentially produce a more bitter or unpleasant taste.

It's not just the taste of your semen that's influenced by diet either - what you eat can also affect sperm count.

Studies show a healthier diet is proven to result in more healthy sperm too.

10. Semen protects sperm cells

Semen offers protection to sperm in a number of different ways. Firstly, it serves as a transportation medium - creating a tiny environment in which sperm can move. Since a woman's internal sex organs are naturally acidic, semen also acts as an alkaline environment that's rich in antioxidants, proteins, and fatty acids to counteract the damage that acidity would cause.

Semen offers protection to sperm in a number of different ways. 

What's more, semen is also thought to help reduce the female body's immune response to foreign substances entering the vagina - further increasing sperm survival rates.

11. It takes over 2 months to create sperm - and it involves chopping your genetic code in half

Although the maturation of sperm we've talked about previously around 2 weeks, the processes involved in sperm production take around 64 days before the sperm is ready to move to the epididymis.

This begins with the mitotic division of spermatogonia - the name for the stem cells that divide to produce more stem cells and spermatocytes, which go on to become sperm cells. At this stage, the cells carry all the genetic information of the person that produced them - but since half genetic information about the life they create will come from the mother, not all this information is needed. As such, these spermatocytes undergo a process called "meiosis," where they effectively cut these genetic instructions in half - ready for combining with another half of the information from the mother's egg.

This is where the body does something amazing - it constantly changes the information that's cut out of the genetic code, so it's very unlikely that two sperm cells are alike. This is done to ensure biological diversity  in a person's children - and is the reason that siblings are not identical (unless they are identical twins).

12. It is possible to be allergic to semen

Although very rare, a semen allergy is a medically recognised condition - know as "seminal plasma hypersensitivity." The allergy actually relates to the proteins found in semen - and symptoms can range from local irritation, such as redness, swelling, and itching in the genital area, to more serious reactions, including hives, difficulty breathing, and even anaphylaxis in the most extreme cases.

The allergy actually relates to the proteins found in semen.

In the decades since the condition was discovered, only a very small number of recorded cases have been logged - but this is likely down to often mild symptoms and the intimate nature the condition - so it could affect many more people than the low numbers might first indicate.

13. A big percentage of sperm is deformed

In science, the size and shape of sperm is referred to as "sperm morphology"  and is considered an important measure - not least because it can affect the sperm's ability to reach and fertilize an egg.

According to the information laid out in the World Health Organization (WHO) guidelines on semen analysis, it is considered normal for only 4% or more of sperm in an ejaculate to have ideal morphology. This means that vast majority - around 96% - may be considered deformed, showing abnormalities in the shape of the head, the mid-section, or the tail.

Since the presence of many deformed sperm is so common, it doesn't actually imply that sperm quality is especially low.

As long as the sperm count and ability to move properly isn't impaired, semen quality is still considered to be normal.

14. One testicle can make enough sperm to create a baby

The human body is amazingly resilient - so people who have had a testicle removed, or been born with just one testicle, can often have a normal sperm count.

This isn't just because one testicle creates enough sperm to fertilize an egg. The male body will often actually adapt to compensate for the loss of a testicle, so the remaining testicle will increase its output to create a normal sperm count.

15. Sperm has to learn to swim

It's easy to consider sperm cells to be so simple that they're likely produced in their final form - but this isn't the case. Sperm are produced in the seminiferous tubules  of the testes, and after production, they move to the epididymis  - a long coiled tube that sits above and behind each testicle.

When being stored in the epididymis, sperm matures - and it's at this point the cells learn to swim. The epididymis actually has three different areas - the caput, the corpus, and the cauda. In the caput, sperm are exposed to an environment rich in proteins and electrolytes - a rich combination that kick-starts the maturing process. As they progress to the corpus, sperm cells acquire their mobility - before moving to the cauda, where they are stored until ejaculation.

Incredible Facts About Sperm, Semen and Ejaculation: A Summary

As men, we likely see our own sperm very frequently - and it's often just taken for granted that our body produces it. In reality though, sperm is nothing short of incredible. Men produce many million sperm cells every day and from the second it's created, it goes through an amazing process inside the body to make sure it's suitable for fertilizing an egg and creating diverse life.

Of course, creating effective sperm is just a small part of the story - the functions that propel it from the penis and give it the very best chance possible of reaching a female egg is another.

The human body has developed biological processes to make sure sperm is effective long after it leaves the penis.

Don't worry, no matter how amazing the process is, masturbation and the constant creation of new sperm is an important part of this process too. So, there's no reason to feel bad every time you add another few milliliters to many liters you'll ejaculate during your lifetime.

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