What Happens If We Throw an Elephant From a Skyscraper? Life & Size 1

Kurzgesagt – In a Nutshell
10 Aug 201706:39

Summary

TLDRThis video script explores the profound impact of size on the biology and survival of living organisms. It begins with a thought experiment involving a mouse, a dog, and an elephant falling from a skyscraper onto a stack of mattresses, illustrating how the mouse survives due to its small size and the elephant doesn't due to its massive size. The video delves into the principles of scaling, explaining how an increase in size leads to a disproportionate increase in surface area and volume, affecting an organism's weight, kinetic energy, and the impact of a fall. It highlights that smaller creatures like insects have a larger surface area relative to their mass, allowing them to survive falls that would be fatal for larger animals. The script also discusses the challenges small organisms face, such as the deadly effects of water due to surface tension, and how insects have evolved to be water-repellent. It touches on the unique adaptations of the smallest insects, like the Fairy Fly, which live in a world where air behaves like a syrup. The video promises to further investigate the reasons behind the lack of extremely large or small species in future episodes, inviting viewers to subscribe for updates.

Takeaways

  • 🐭 The mouse survives a fall from a skyscraper because of its small size and the principle of scaling, which affects how gravity impacts different sizes.
  • 🐘 An elephant explodes upon impact due to its large size having a small surface area relative to its volume, leading to a high concentration of kinetic energy.
  • 🐶 The dog dies from the fall because its size does not offer the same protective benefits against gravity as the mouse, resulting in fatal injuries.
  • 🔢 Size is a crucial factor in determining the biology and experiences of living beings, with different sizes living in unique environments with distinct rules.
  • 🌐 Life spans across a vast range of sizes, from bacteria to blue whales, each with their own advantages and challenges.
  • 🎾 The physical laws affecting living things change with size, impacting how they are built and how they live and die.
  • 🌌 Small creatures like insects have a large surface area relative to their mass, which allows them to survive falls that would be deadly to larger animals.
  • 💧 Insects face different challenges, such as the deadly effects of water due to surface tension, which is much stronger relative to their size.
  • 🦟 Insects have evolved adaptations like water-repellent exoskeletons and tiny hairs to combat the dangers of water's surface tension.
  • 🕷️ Some insects use surface tension to 'breathe' underwater by trapping an air bubble around them, allowing for gas exchange.
  • 🦋 The smallest insects, like the Fairy Fly, experience the world very differently, with air acting more like a thick fluid that they must swim through.
  • 🤔 The video script raises questions about why certain sizes do not exist, such as ants the size of horses or elephants the size of amoeba, to be explored in future content.

Q & A

  • Why does the mouse survive the fall from the skyscraper but the dog and the elephant do not?

    -The mouse survives due to its small size, which allows it to have a larger surface area relative to its mass, distributing the impact and allowing air resistance to slow it down. In contrast, the elephant and dog, being much larger, have less surface area relative to their volume, leading to a more severe impact and no significant air resistance to cushion their fall.

  • What principle is highlighted in the script that explains the survival of the mouse and the death of the dog and elephant?

    -The script highlights the principle of scaling size, which changes everything in terms of physics and biology. The relative surface area to volume ratio plays a crucial role in how animals experience forces like gravity and air resistance.

  • How does the script explain the impact of gravity on very small and very large animals?

    -The script explains that very small animals are practically immune to the effects of gravity due to their large surface area relative to mass, which allows them to fall from great heights without harm. Conversely, very large animals, like elephants, have a small surface area relative to their volume, leading to a concentrated impact and destruction upon landing.

  • What are the three features of a theoretical spherical animal mentioned in the script, and how do they change with size?

    -The three features are length, surface area, and volume. When the animal's size is increased, its skin (surface area) grows by the square of the increase, and its volume (and thus mass) grows by the cube of the increase, which significantly affects its weight and the impact of a fall.

  • Why is the force of water's surface tension potentially deadly for insects?

    -Water's surface tension acts like an 'invisible skin' that is weak for larger animals but strong for insects due to their small size. This force can be so strong that getting wet is a matter of life and death for insects, as it can quickly engulf them and make it difficult for them to break free, leading to drowning.

  • How have insects evolved to deal with the threat of water's surface tension?

    -Insects have evolved to be water repellent. Their exoskeletons are often covered with a thin layer of wax, and many have tiny hairs that increase their surface area and prevent water droplets from touching their exoskeleton, making it easier to shed water.

  • What adaptation allows some insects to 'breathe' underwater using surface tension?

    -Some insects have evolved a surface covered by a short and extremely dense coat of water-repelling hair. When they dive underwater, air stays inside their fur, forming an air bubble. This allows oxygen to diffuse into the bubble from the surrounding water while carbon dioxide diffuses out, effectively acting as an external lung.

  • How does the script describe the experience of air for the smallest insects, like the Fairy Fly?

    -For the smallest insects, like the Fairy Fly, air is described as being more like a thin jello or syrup-like mass, making movement through it difficult. They have to 'swim' through the air rather than glide, with their wings resembling big hairy arms.

  • What are some of the physical rules that change as life grows in size, according to the script?

    -The script suggests that as life grows in size, the physical rules change significantly. For example, gravity, air resistance, and surface tension have different impacts on organisms of different sizes, leading to unique adaptations and limitations for each size category.

  • What questions are posed by the script regarding the size of animals, and what will be discussed in the next part of the series?

    -The script poses questions about why there are no ants the size of horses or elephants the size of amoeba. These questions set up the discussion for the next part of the series, where the reasons behind these size limitations will be explored.

Outlines

00:00

🐭 The Impact of Size on Survival

This paragraph explores the concept of size as a critical factor in the survival of living organisms. It begins with a thought experiment involving a mouse, a dog, and an elephant falling from a skyscraper, highlighting the mouse's survival due to its small size. The script delves into the physical laws that affect organisms of different sizes, explaining how smaller creatures are less affected by gravity and have a higher surface area to volume ratio, which softens impacts and allows for a greater resistance to falling. The paragraph also touches on the challenges faced by smaller organisms, such as the deadly effects of surface tension in water for insects. It sets the stage for a series of videos examining the unique rules and experiences of different sizes in the animal kingdom.

05:02

🔬 The Microscopic World and Evolutionary Adaptations

The second paragraph delves into the peculiarities of the microscopic world, focusing on the challenges faced by very small insects like the Fairy Fly. It describes how these tiny creatures navigate an environment where even air behaves like a thick fluid, requiring them to 'swim' through it. The paragraph discusses the evolutionary adaptations that have allowed insects to survive in their unique universe, such as water-repellent exoskeletons and tiny hairs that prevent water from sticking to them. It also explains how some insects use surface tension to 'breathe' underwater by carrying an air bubble with them. The script raises intriguing questions about the limits of size in the natural world and promises further exploration in upcoming videos, while inviting viewers to subscribe to a newsletter for more content.

Mindmap

Keywords

💡Size

Size is a fundamental attribute of living organisms that significantly influences their biology, behavior, and survival. In the video, size is presented as the most underappreciated regulator of living things, determining how organisms are built, experience the world, and live and die. The script uses the dramatic example of a mouse, a dog, and an elephant falling from a skyscraper to illustrate how size affects the outcome of such an event, with the mouse surviving due to its small size and the elephant not surviving due to its large size.

💡Scaling

Scaling refers to the principle that changes in size lead to changes in proportions and properties. The video discusses how scaling size changes everything, particularly in the context of how different-sized animals are affected by gravity and impact forces. For instance, when an animal's size increases, its volume and mass increase at a much faster rate than its surface area, affecting how it experiences a fall and the impact upon landing.

💡Surface Area

Surface area is the total area that the surface of an object occupies. The video explains that surface area plays a crucial role in how animals are affected by impacts and air resistance. It is used to illustrate the concept that larger animals, like elephants, have less surface area relative to their volume, leading to a more severe impact when falling, while smaller animals, like insects, have a larger surface area relative to their mass, allowing them to survive falls that would be lethal to larger creatures.

💡Volume

Volume is the measure of the amount of space an object occupies. In the context of the video, volume is directly related to an animal's mass and the kinetic energy it possesses before impact. The script explains that an increase in volume leads to a significant increase in mass and kinetic energy, which results in a stronger impact shock when an animal hits the ground, as exemplified by the fate of the elephant in the hypothetical scenario.

💡Kinetic Energy

Kinetic energy is the energy that an object possesses due to its motion. The video script uses kinetic energy to explain why larger animals are more severely affected by falls. It states that the more mass an animal has, the higher its kinetic energy before hitting the ground, leading to a stronger impact shock. This concept is applied to the contrasting fates of the mouse and the elephant in the fall scenario.

💡Air Resistance

Air resistance is the force that opposes the motion of an object through the air. The video explains that air resistance plays a significant role in slowing down an object in free fall. It is used to illustrate how smaller animals, like insects, experience less impact due to greater air resistance relative to their mass, while larger animals, like elephants, are less affected by air resistance due to their size, leading to a more devastating impact upon landing.

💡Cohesion

Cohesion is the intermolecular force that causes molecules of the same substance to stick together. In the video, cohesion is discussed in the context of water's surface tension, which is a significant force for small insects. The script explains that water's cohesive properties create a surface tension that can be deadly for insects due to their small size and large surface area relative to mass.

💡Surface Tension

Surface tension is the elasticity of a liquid's surface due to the cohesive forces between its molecules. The video uses the concept of surface tension to explain why water can be a deadly substance for small insects. It is described as an 'invisible skin' on the surface of water that is strong enough to engulf and drown small insects like ants due to their size and inability to break the surface tension.

💡Exoskeleton

An exoskeleton is a rigid external covering that provides support and protection for some animals, such as insects. The video mentions that insects have evolved exoskeletons covered with a thin layer of wax to make their surface water-repellent. This adaptation helps them to survive in environments where surface tension could be a threat, illustrating the evolutionary response to the challenges posed by an animal's size and the physical properties of its environment.

💡Evolution

Evolution is the process by which different kinds of living organisms have developed and diversified from earlier forms during the history of the earth. The video discusses how evolution has led to various adaptations in response to the physical rules that differ for each size of organism. It gives examples of how insects have evolved features like water-repellent exoskeletons and tiny hairs to cope with the challenges of their small size, such as the deadly effects of surface tension.

💡Fairy Fly

The Fairy Fly is mentioned in the video as one of the smallest insects, about half the size of a grain of salt, living in a world where even air behaves like a syrup-like mass. The script uses the Fairy Fly to illustrate how the environment becomes increasingly strange and challenging as one explores the diversity of different sizes. It highlights the unique adaptations and the different physical rules that apply to life at such a small scale.

Highlights

Size is the most underappreciated regulator of living things, affecting biology, construction, experience, and lifespan.

Physical laws differ for animals of different sizes, impacting how they live and die.

Small animals are practically immune to falling from great heights due to the effect of gravity on their size.

Scaling size changes everything, impacting how falling affects an animal's survival.

The relationship between an animal's surface area, volume, and mass determines the impact of a fall.

Elephants have a small surface area relative to volume, leading to a devastating impact when falling.

Insects have a large surface area relative to mass, allowing them to survive falls that would harm larger animals.

Surface tension is a deadly force for small insects due to its strong effect relative to their size.

Insects have evolved to be water-repellent to counteract the life-threatening effects of surface tension.

Some insects use nanotechnology-evolved water-repelling hairs to breathe underwater利用 surface tension.

As size decreases, even air becomes more solid, affecting the movement of the smallest insects.

The Fairy Fly, one of the smallest insects, swims through air that is like a syrup to them.

Different sizes experience unique physical rules, leading to diverse evolutionary adaptations.

The video series will explore why there are no ants the size of horses or elephants the size of amoeba.

A monthly newsletter is available for updates on new videos and bonus content.

Transcripts

play00:00

Let's start this video by throwing a mouse, a dog, and an elephant

play00:04

from a skyscraper onto something soft.

play00:06

Let's say, a stack of mattresses.

play00:09

The mouse lands and is stunned for a moment,

play00:11

before it shakes itself off,

play00:12

and walks away pretty annoyed,

play00:14

because that's a very rude thing to do.

play00:16

The dog breaks all of its bones

play00:18

and dies in an unspectacular way,

play00:20

and the elephant explodes into a red puddle of bones and insides

play00:24

and has no chance to be annoyed.

play00:26

Why does the mouse survive,

play00:27

but the elephant and dog don't?

play00:30

The answer is size.

play00:32

Size is the most underappreciated regulator of living things.

play00:36

Size determines everything about our biology,

play00:39

how we are built, how we experience the world, how we live and die.

play00:43

It does so because the physical laws are different for different sized animals.

play00:47

Life spans seven orders of magnitude, from invisible bacteria to mites, ants,

play00:54

mice, dogs, humans, elephants and, blue whales. Every size lives in its own

play01:00

unique universe right next to each other, each with its own rules, upsides, and

play01:05

downsides. We'll explore these different worlds in a series of videos. Let's get

play01:11

back to the initial question: Why did our mouse survive the fall? Because of how

play01:17

scaling size changes everything; a principle that we'll meet over and

play01:21

over again. Very small things, for example, are practically immune to falling from

play01:26

great heights because the smaller you are the less you care about the effect

play01:30

of gravity. Imagine a theoretical spherical animal

play01:34

the size of a marble. It has three features: its length, its surface area,

play01:38

(which is covered in skin) and its volume, or all the stuff inside it like organs,

play01:43

muscles, hopes and dreams. If we make it ten times longer, say the size of a

play01:49

basketball, the rest of its features don't just grow ten times. Its skin will

play01:54

grow 100 times and it's inside (so it's volume) grows by 1000 times. The volume

play02:01

determines the weight, or more accurately, mass of the animal. The more mass you

play02:06

have, the higher your kinetic energy before you hit the ground and the

play02:09

stronger the impact shock. The more surface area in relation to your volume

play02:14

or mass you have, the more the impact gets distributed and softened, and also

play02:18

the more air resistance will slow you down. An elephant is so big that it has

play02:23

extremely little surface area in ratio to its volume. So a lot of kinetic energy

play02:27

gets distributed over a small space and the air doesn't slow it down much at all.

play02:31

That's why it's completely destroyed in an impressive explosion of goo when it

play02:36

hits the ground. The other extreme, insects, have a huge surface area in

play02:41

relation to their tiny mass so you can literally throw an ant from an airplane

play02:44

and it will not be seriously harmed. But while falling is irrelevant in the small

play02:49

world there are other forces for the harmless for us but extremely dangerous

play02:53

for small beings. Like surface tension which turns water into a potentially

play02:58

deadly substance for insects. How does it work? Water has the tendency to stick to

play03:04

itself; its molecules are attracted to each other through a force called

play03:08

cohesion which creates a tension on its surface that you can imagine as a sort

play03:12

of invisible skin. For us this skin is so weak that we don't even notice it

play03:17

normally. If you get wet about 800 grams of water or about one percent of your

play03:22

body weight sticks to you. A wet mouse has about 3 grams of water sticking to

play03:26

it, which is more than 10% of its body weight. Imagine having eight full water

play03:31

bottle sticking to you when you leave the shower. But for an insect the force

play03:36

of water surface tension is so strong that getting wet is a question of life

play03:40

and death. If we were to shrink you to the size of

play03:43

an ant and you touch water it would be like you were reaching into glue. It

play03:47

would quickly engulf you, its surface tension too hard for you to break and

play03:51

you'd drown. So insects evolved to be water repellent. For one their exoskeleton is

play03:58

covered with a thin layer of wax just like a car. This makes their surface at

play04:02

least partly water repellent because it can't stick to it very well. Many insects

play04:07

are also covered with tiny hairs that serve as a barrier. They vastly increase

play04:12

their surface area and prevent the droplets from touching their exoskeleton

play04:16

and make it easier to get rid of droplets. To make use of surface tension

play04:20

evolution cracked nanotechnology billions of years before us. Some insects

play04:26

have evolved a surface covered by a short and extremely dense coat of water

play04:30

repelling hair. Some have more than a million hairs per square millimeter when

play04:35

the insect dives under water air stays inside their fur and forms a coat of air.

play04:40

Water can't enter it because their hairs are too tiny to break its surface tension.

play04:44

But it gets even better, as the oxygen of the air bubble runs out, new oxygen

play04:49

diffuses into the bubble from the water around, it while the carbon dioxide

play04:52

diffuses outwards into the water. And so the insect carries its own outside lung

play04:58

around and can basically breathe underwater thanks to surface tension.

play05:01

This is the same principle that enables pond skaters to walk on water by the way,

play05:06

tiny anti-water hairs. The smaller you get the weirder the environment becomes. At

play05:12

some point even air becomes more and more solid. Let's now zoom down to the

play05:17

smallest insects known, about half the size of a grain of salt,

play05:21

only 0.15 millimeters long: the Fairy Fly. They live in a world even weirder than

play05:27

another insects. For them air itself is like thin jello, a syrup-like mass

play05:32

surrounding them at all times. Movement through it is not easy. Flying

play05:37

on this level is not like elegant gliding; they have to kind of grab and

play05:41

hold onto air. So their wings look like big hairy arms rather than proper insect

play05:46

wings. They literally swim through the air, like a tiny gross alien through

play05:51

syrup. Things only become stranger from here on

play05:55

as we explore more diversity of different sizes. The physical rules are

play05:59

so different for each size that evolution had to engineer around them

play06:03

over and over as life grew in size in the last billion years. So why are there

play06:08

no ants the size of horses? Why are no elephants the size of amoeba? Why?

play06:14

We'll discuss this in the next part.

play06:18

We have a monthly newsletter now, sign up if

play06:21

you don't want to miss new videos and for bonus videos.

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Related Tags
Size ImpactBiologySurvivalPhysicsAnimal ScaleGravity EffectsEvolutionInsect AdaptationSurface TensionAir Resistance