1. Human fingers have no muscles. We are able to move our fingers thanks to the combination of bones, tendons, and muscles, which are present in our palms and forearms.

Human hands are fairly complex structures. They are made up of 27 bones, 34 muscles, countless tendons, blood vessels, nerve fibers, and a thin layer of skin covers all of that. Another fascinating, and maybe even a bit surprising fact, is that human fingers do not have any muscles! So, how do we move them?

To answer that question, we first need to talk about the anatomy of our fingers. There are three phalanges (bones) in each finger, and they are named based on how far they are located from the palm. The farthest one from the palm is called the “distal” phalange, then there is the “middle” phalange, and the closest one is called the “proximal” phalange. The first knuckle is named the “metacarpophalangeal joint” or MCP, the second knuckle is called the “proximal interphalangeal joint” or PIP, and the third knuckle is called the “distal interphalangeal joint” or DIP. The next important features are the tendons, which connect muscles to bones. Ligaments, on the other hand, connect bones to bones.

The tendons in our fingers are connected to 17 muscles present in the palm and 18 muscles in the forearm. There are no muscles in the fingers themselves. The muscles are known as “flexors” help us close our hands, and the muscles called “extensors” help us open them. The small muscles help us control each finger. Some of these muscles are present in the palm, while others are found in the forearm. The ones in the palm are called “intrinsic muscles,” and the ones in the forearm are called “extrinsic muscles.” (12)

2. Plants communicate with each other through the internet of fungus.

The mycelium of a fungus spreading through the soil.

Did you know that plants use an underground, fungal network to speak to each other? While it may sound like science fiction, it is actually true. Fungi are made up of thin threads called mycelium, which are crucial components of this underground internet. The mycelium links the roots of plants and creates a communication channel between them.

For example, if you have a tree in the garden, it is most likely connected to a bush that is several meters away. This fungal network actually helps plants to share nutrients with their neighbors. In some cases, this “wood wide web” can spread toxic chemicals to sabotage the spread of unwelcome plants. (12)

3. Jet engines operate at temperatures well above the melting points of the materials that they are constructed from.

The engine of a jet airplane can get hotter than lava! Such high temperatures are actually way above the melting point of the materials used. So, how do they stay intact and functional? To understand that, you first need to have a basic idea of how jet engines operate.

In basic jet engines, air enters through the front intakes, and it is then compressed. From there, the air enters into the combustion chambers where fuel and air are combined and ignited. As a result, gases form and rapidly expand until they are expelled through the backside of the combustion chamber. The gases exert the same amount of force in all the directions and provide a forward thrust. When leaving the engine, these gases pass through turbines, which consist of fan-like blades. The blades rotate a shaft known as turbine shaft, which in turn, rotates the compressor. The process provides a supply of fresh air that enters through the intake.

The turbines generate power that drives the compressor and the other accessories. To accomplish this, the turbines have to extract energy from the gases that the combustion system releases. However, the constant flow of hot gases also exposes the turbines to temperatures between 850° C and 1,700° C, which is way above the melting point of the materials used. Though the blades of the turbines glow red-hot, they remain strong enough to function properly. That is because these blades have many small holes that help pass cool air through them and keep the blades from melting. (12)

4. That uncomfortable sensation of small insects crawling on your skin is called “formication.” A number of things can cause this, but it can occur when static electricity attracts particulates to the skin.

Have you ever had that uncomfortable feeling where you thought insects were crawling on or inside your skin even though there was nothing? More often than not, this abnormal skin condition is just a tactile hallucination, and it is called “formication.” Part of a broad condition called “paresthesias,” formication can be caused by numerous factors. Those who experience it describe it as a feeling of tingling, itchiness, burning, pins and needles, or even pain.

In most cases, the sensation occurs without any external triggers. However, sometimes it may be caused due to static electricity attracting particulates to your skin or causing movement in body hair. Other causes of formication include medical conditions such as neurocysticercosis, herpes zoster, Lyme disease, syphilis, skin cancer, mercury poisoning, diabetic neuropathy, and pesticide exposure. (1, 2)

5. Hippos produce reddish-pink sweat, which also acts as a natural sunblock.

Did you know that ancient Greeks were puzzled by the fact that hippos sweat blood? Today, we know that the reddish oily fluid is not actually blood or sweat, for that matter. In humans and most other mammals, sweat secretes out onto the skin, evaporates, and cools off the body.

Hippo sweat, on the other hand, comes out of special glands that are big, deep, and present all over their skin. This fluid appears red or reddish-pink under sunlight, and it does not evaporate. Hippo sweat is also water repellant, and it acts as a moisturizer with antibiotic properties.

Japanese researchers have found that the red pigment in hippo sweat prevents the growth of disease-causing bacteria. Further tests have also revealed that the pigments are capable of absorbing ultraviolet light. Therefore, hippo sweat acts as a natural sunscreen. (12)

6. Whispering can damage your voice.

Most people tend to whisper when suffering from laryngitis and other similar throat problems. While you may think speaking softly using your breath helps to heal your voice, medical professionals opine that whispering actually puts more pressure on your vocal cords, which is harmful to your voice.

Various studies have shown that whispering damages the larynx more than usual speech. Though you may not realize it, whispering actually requires more effort. In fact, when public speakers, singers, and performers need vocal rest, doctors advise against whispering. If you don’t want to strain your pipes, you better use your normal voice! (12)

7. The tendency to see faces in objects is actually a psychological condition called “pareidolia.”

Humans have long seen faces in unlikely places such as the moon, burnt toast, and oddly-shaped vegetables. While it was once considered as one of the symptoms of psychosis, it is now viewed as a normal human tendency, and it is called “pareidolia.” Pretty much everyone has experienced this psychological phenomenon, and though it primarily makes you see familiar patterns in random or vague images, pareidolia can also extend to sound. That includes hearing hidden messages in music when it is played at a lower or higher speed than normal or played in reverse.

One explanation behind pareidolia is that the human brain is especially good at perceiving faces. In fact, there is an entire region called the “fusiform face area” dedicated to recognizing faces. These neurons are so active that they seek faces even when there is none to be found. (12)

8. All giant pandas in zoos around the world are on loan from China.

Everyone likes pandas! They are cute, cuddly, and rather precious. Sadly, they are also on the IUCN Red List, which means they are a threatened species, and they need to be protected. Though pandas are native to south-central China, they can be found in 27 zoos in a total of 21 countries across the world as of 2019. However, none of these countries actually own the giant pandas, China simply loans them the animal.

China makes contracts with international zoos, which allows these zoos to house the giant pandas for a few years. Once the species reproduce, they are brought back to their native land. American zoos are known to pay up to $1 million just to rent one panda for a year. Most zoos go for a ten-year contract, and if the adult panda reproduces, the zoo has to pay a one-time “baby tax” of an additional $400,000.

Having a panda also proves beneficial for the zoos as most of them experience a surge in the number of visitors and overall profit. (1, 2)

9. Once a year, in the Honduran city of Yoro, it rains fish.

What would you do if you ever witnessed fish falling from the sky? For the last 100 years or so, a Honduran city has experienced similarly bizarre weather events. The small town of Yoro is famous around the world for the “Rain of Fish,” known locally as “Lluvia de Peces.” It occurs once (sometimes twice) a year, typically in May or June, and during this event, hundreds of silverfish rain down from the sky. A massive rainstorm takes place, and when the storm subsides, you can find the streets filled with flapping and flopping fish.

A team associated with National Geographic actually witnessed and documented the event in the 1970s. However, they could not verify whether the fish were actually falling from the sky or coming from another source. Similar events have been reported throughout the world, and scientists have named the phenomenon “animal rain.” However, no one knows for certain what causes it.

Possible explanations include floods filling the streets with fish, large rainstorms forcing these animals out, and flash floods depositing the fish and then quickly drying up, all of which makes the spectators believe that the fish fell from the sky. (1, 2)

10. Male platypuses produce venom.

The platypus, one of nature’s strange creations, had puzzled scientists when it was first discovered. Its webbed feet and bill may remind you of a duck, but it has the furry body of an otter and the tail of a beaver. Naturally, most experts thought that it was the result of animal experimentation. Though we have acclimatized to them now, a lot of people are unaware that male platypuses are venomous.

In fact, they are among the very few living mammals that naturally produce venom. The males of the species have a couple of spurs on their back legs. These spurs become active and secrete venom during the mating season. That has led experts to believe that the platypus uses it to eliminate sexual competition and not necessarily for protection. Though the venom is excruciatingly painful to humans, it is not fatal. (12)

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