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Dive into the mesmerizing world of the animal kingdom as we compare the most peculiar and extraordinary eyes found in nature.
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00:00Wait, don't tell me that life on Earth has bubbled for about 3.5 billion years,
00:05and the biggest creature we got is the blue whale?
00:08I mean, not bad, but that doesn't sound nearly as fun as those cool giant creatures you get to see
00:14in movies.
00:15Yeah, you recognize the iconic roar here.
00:18It appeared on TV, in comic books, in video games, and in cinema.
00:23I mean, come on.
00:24It even got its own star on the Hollywood Walk of Fame on its 50th birthday.
00:28So, what would it take to get good old Godzilla from the TV screen to our streets?
00:36And we're talking about the beast that's really gigantic.
00:40In the original film from 1954, Godzilla was thought to be 164 feet tall.
00:46This was the perfect height for the monster to just peer over the biggest buildings in Tokyo at the time.
00:52But as further movies came, Godzilla became bigger and bigger.
00:58In theory, this would be the biggest animal that could exist and not end up crushed by the gravitational field
01:05of our planet.
01:06Even if we're talking about some tiny Godzilla of, let's say, 14,000 tons.
01:12To take the gravitational force of our planet and carry such weight, Godzilla must have some incredibly strong bones.
01:19And as an object gets bigger, its volume will actually increase faster than its surface area.
01:27Okay, wait, let's start small.
01:30So, cells are the building blocks of life, and they come in all shapes and sizes.
01:35But the thing is, cells have a problem when they try to grow too big.
01:39As they grow, their surface area, the outside, doesn't keep up with their volume, which means the inside.
01:47It's like having a big mouth but a tiny stomach.
01:51You can't digest all the food you want to eat.
01:54Ugh, why haven't I learned that already?
01:56Especially when I open my fridge for a midnight snack.
02:01So, if cells get too big, they can't get enough nutrients in and waste out fast enough.
02:07It would be like living in a very big house, but with just one tiny door to go in and
02:12out.
02:13Plus, that's not their only problem.
02:15Cells also need to be able to divide and replicate.
02:19And this task gets tricky as they get bigger.
02:22They need this thing called microtubules for that.
02:25It's sort of like a skeleton that gives them structure.
02:30But don't worry, evolution is a foxy little thing.
02:34There are some cells out there, like a specific type of invasive algae,
02:38that have found ways to break the rules and get really big.
02:42And they don't even need to divide to do that.
02:45This algae could pass as an aquatic fern that has fronds up to 31 inches long.
02:51But what you're looking at is just one big cell.
02:56It has multiple nuclei, though.
02:58Which are like the control centers of cells.
03:01Plus, there are even some bacteria that are living in a symbiotic relationship with the organism.
03:07Which means they help each other out when necessary.
03:10It's like having a bunch of different rooms inside one big house.
03:13With some roommates living there that help around from time to time.
03:19Then there's a monster algae known as the sailor's eyeball, which is like a giant ball of green slime.
03:26It can grow up to 2 inches in diameter, but is also considered to be just a single cell.
03:34My personal favorite would be this one.
03:37Again, we're talking about a single cell.
03:40But check out its stem and cap.
03:42It looks like a tiny little umbrella.
03:45It can grow up to 4 inches tall, which is definitely not bad for a single cell.
03:50Most cells are too small to see with the naked eye.
03:53But these fellas don't hesitate to break the rules.
03:58Now, when it comes to animals getting really big, there's a limit to their size.
04:03It's like trying to build a really tall tower.
04:06Eventually, it'll become too heavy and the base won't be able to support the weight anymore.
04:11Similarly, when an animal gets really big, its bones and muscles have to evolve to support all that weight.
04:18And it becomes more and more difficult to do so.
04:20In one of the movies, Godzilla was 390 feet tall.
04:25At that size, it would be really difficult for its heart to pump blood to its brain.
04:32And if it was a reptile, Godzilla would need to spend all of its time lying in the sun to
04:37stay warm.
04:38So, we'd have to hide in the shadows, hoping some bigger animals that live in warm areas could keep it
04:45full.
04:45If Godzilla was a mammal, though, it would generate too much body heat and end up cooking itself.
04:53The biggest land animals we know of were sauropods, a type of dinosaur with a really long neck and tail.
05:00They could grow up to 131 feet long and weigh up to 70 tons, which could be as heavy as
05:0710 elephants.
05:08Evolution was pretty efficient when it had to come up with its body plan.
05:12Sauropods ate plants.
05:14They had a smart way of eating that allowed them to stay in one spot and still find enough food.
05:20They could move their long necks around to reach plants so they didn't have to walk around too much or
05:25waste too much energy.
05:27Yeah, my kind of folks.
05:31That's impressive, but let's get realistic.
05:34Not many giant animals are happy to eat salad for dinner.
05:37If you had a giant beast such as Godzilla, you can expect it to go after its prey.
05:43And that becomes too hard for its body to support all that weight and perform all the necessary activities.
05:51The largest meat-eating dinosaurs were still pretty big, but not as big as the sauropods.
05:57The biggest one we know of is a fella called Spinosaurus, which was about 50 feet long.
06:03It managed to survive by eating fish and some other creatures that lived in the water.
06:08It would be so cool to have Godzilla in real life.
06:11If you have some safe basement where it won't find you, of course.
06:15But it's not likely some animal could really get bigger than our beloved sauropod.
06:20At least, not without running into some serious physical limitations.
06:25And have you ever wondered how big a plant could get?
06:29It turns out some trees have already reached amazing heights.
06:33Such as the General Sherman, the largest living tree on the planet.
06:37It's more than 275 feet tall and has nearly 53,000 cubic feet of wood.
06:43It's gigantic, but still a little bit smaller than the Lindsay Creek French tree.
06:49The biggest tree ever recorded.
06:51It was a coast redwood, 390 feet tall, and had a volume of more than 90,000 cubic feet,
06:58which is as big as some skyscrapers.
07:03But it ain't easy for plants to get big either.
07:06When they're tall, it's tricky for them to get water from the roots to the leaves.
07:11Redwoods have a couple of tricks up their sleeves, though.
07:14For example, they absorb moisture from fog through their leaves.
07:18Plus, they have a wide base that gives them more support.
07:22If we want to build taller buildings, we also need to think about the challenges plants face,
07:27like how to build a good base that will support the structure and transport water and nutrients.
07:35If we're not just looking for height, we can take a peek at other massive organisms on our home planet,
07:41such as Pando.
07:42This is a male aspen forest in Utah that covers 107 acres and is basically one giant organism.
07:50It weighs almost 6,000 tons and is one of the biggest organisms on Earth.
07:56Perfect salad bowl for Godzilla.
08:00I mean, plants aren't the only organisms that can grow to massive sizes.
08:04There are fungi, like the honey mushroom, that can grow into a network of tiny threads called hyphae.
08:11They tend to spread out over big areas.
08:14And it's like a pretty big underground web, connecting everything together.
08:18One specimen in Michigan covers 90 acres and weighs about 400 tons.
08:24Now, that's a lot of mushrooms.
08:26The largest eyes in the animal kingdom belong to the colossal squid.
08:30This creature most likely has the biggest pair of eyes that have ever existed on our planet.
08:35They measure an astonishing 11 inches across, which makes them the size of a basketball.
08:42The colossal squid needs such eyes not only to see its prey better, but also to protect itself from underwater
08:49predators.
08:50Its eyes face forward, giving the squid binocular vision.
08:54Another type of squid, called the giant squid, has its eyes placed on each side of its head.
09:00This allows the animal to see predators too.
09:02But since it lacks that binocular vision, it's not very good at estimating distances.
09:08The colossal squid, like many other squid species, has a fascinating feature called light organs, one in each eyeball.
09:16Those light organs are made of vertical lines located in the back of their eyeballs.
09:22These organs are similar to the headlights of a car.
09:26But even though the colossal squid has this really cool feature, it most likely doesn't have color vision.
09:32Most deep-sea animals don't either.
09:34But it's not like they need it much in the depths of the ocean, where it gets really dark.
09:40Humans, for example, have eyes that can only detect light at a depth of around 1,600 to 2,000
09:46feet.
09:47Since colossal squids are found at more than 3,200 feet below the surface,
09:53they need to adapt to be able to see in almost pitch-black darkness.
09:58That's why they also have very large pupils, almost 3 inches across.
10:02It helps them collect every single particle of light in those harsh environments.
10:08Big eyes don't necessarily mean big bodies.
10:11Just ask tarsiers.
10:13They're a group of primates that have the biggest eye-to-body size ratio.
10:17Each of their eyes is just as big as their brain.
10:20You can find these golem-looking animals in Southeast Asia.
10:24Because they have such big eyes, these small animals aren't able to rotate them fully.
10:29So, they have to rely on their necks to get a better field of vision.
10:34Similar to owls, their necks can rotate about 180 degrees on each side.
10:40Tarsiers are nocturnal animals that use these quirky-looking eyes to look for prey.
10:45They don't put much effort apart from that.
10:47They just wait for their prey to approach them instead, sitting patiently in the dark.
10:52Speaking of small but effective eyes, some types of dragonfly eyes come equipped with about 28,000 lenses.
11:00That's more than any other living animal.
11:02And since their peepers cover almost their entire head, they have perfect 360-degree vision.
11:09But can an animal survive without eyelids?
11:12Most living beings have evolved to have eyelids to help protect their eyes from debris.
11:17Eyelids also help us in super-bright environments or when we're exposed to high heat.
11:23Last but certainly not least, eyelids help keep eyes lubricated so that they don't dry out and lose their functions.
11:30Well, check out nocturnal geckos.
11:33They don't have eyelids, but they came up with another unique method.
11:36They have to rely on their tongues to keep their eyes lubricated and clean.
11:41They also see really well in dim light because, in the nighttime, their vision is 350 times more sensitive to
11:49color than ours.
11:50I mean, I'd certainly love to have eyes that change color every now and then, but unfortunately for me, I
11:56wasn't born an arctic reindeer.
11:59Their eyes can switch colors depending on the season.
12:02In the summer, for example, their eyes turn gold, whilst during the colder months, they have blue eyes.
12:09These animals have adapted to this color flexibility because of their ever-changing light levels in their harsh habitat.
12:18Ever heard of a fish with four eyes?
12:20Its official name is anablips, and it has a special ability to see both above and below the waterline simultaneously.
12:28How come?
12:29Because its eyes are split in half by a horizontal line.
12:33Each of those half eyes comes with its own pupil and retina, which means they can act separately.
12:39This unique disposition of its eyes allows the fish to see both predators in the sky and spot insects on
12:46land.
12:47Those make up for most of its menu.
12:50Ostriches have eyes that are bigger than their brains.
12:53They also have the largest eyes out of all terrestrial animals, since they measure about 2 inches across.
13:00But if you look closely, you'll also see that ostriches have eyes with long, dense lashes.
13:06They're not really lashes, though, since they're not made of hair.
13:09Those long strands are actually more related to feathers and help these huge birds with some added shade and protection
13:16against flying sand.
13:19Some of the best eyes out there are those of chameleons.
13:23They have the ability to move independently, which gives these reptiles almost 360-degree vision.
13:42California's purple sea urchin is basically one single functioning eye.
13:47That's because the whole surface of its body is filled with photoreceptors.
13:51That makes the sea urchin sensitive to light, which means it can see in every direction.
13:56It does need to focus the light for better vision once in a while.
14:00The creature uses its spines to stop some of the light from hitting its body.
14:06Some eyes in the animal kingdom need to adapt to really hot climates, like those of camels, for example.
14:13These animals have really long lashes that help them keep away the sand.
14:18A camel's eye also features a third eyelid.
14:21But this one sweeps across from the corner of each eye.
14:25Because their environment is filled with small particles of dust,
14:29they need to clean their eyes more frequently than other species.
14:34Owls have eyes that share one great feature with those of humans.
14:38They can see in 3D, much like any other predators.
14:42Owls need this to better calculate the distance towards their prey.
14:45But here comes the problem.
14:47How do those gigantic eyes fit into the small skull of an owl?
14:52Turns out that these birds had to redesign their eye shape.
14:56An owl's eye is not a sphere.
14:59It's more elongated.
15:01The bones in the bird's skull have a special feature called a sclerotic ring.
15:05It helps support these huge eyes and holds them in place.
15:09But because of these rings, owls can't rotate their eyes,
15:12which are always looking straight ahead.
15:15Instead, they have to rely on their necks to see around.
15:20The mantis shrimp has probably the most complex eyes in the entire animal kingdom.
15:25Us humans only have 3 types of cones in our eyes.
15:28This gives us the ability to see the colors red through violet.
15:32The mantis shrimp has 16 types of cones.
15:36They might not see different colors from those we do,
15:39but they do have one of the best color recognition systems out there.
15:42But these extreme color receptors allow them to react to every small change in hue really fast, avoiding predators.
15:50When you think about animals with huge unique peepers, sheep and goats aren't the first on your list, right?
15:56Don't dismiss them so quickly, though, as a goat's pupils are shaped like horizontal lines.
16:02And that comes with its own purpose.
16:06Data provided by researchers point out that the pupil shape and eye orientation are related to the daily activities of
16:13each type of animal.
16:14Take bigger daytime predators like wolves, for example.
16:18Most of them have forward-facing eyes and round pupils.
16:22On the other hand, smaller animals like snakes, cats, or foxes that go and look for food both during the
16:29day and at night
16:30come with vertical-slip pupils, better adapted for night vision.
16:34More vulnerable animals like horses and deer need to be constantly on their toes,
16:39so they've adapted to have wide and narrow horizontal pupils.
16:43This allows them to stretch their field of vision, which is wider than that of any other animal.
16:49Also, when they keep their head low, their eyes rotate, and they keep a watch on their surroundings.
16:54Thanks.
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