eyes

WTF Fun Fact 13586 – Giant Squid Eyes

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Did you know that giant squid eyes are the size of beach balls?

You might be able to surmise that a giant squid is…well, giant, simply by its name. And it stands to reason that a giant creature would also have giant body parts. But beach ball-sized eyes is a pretty amazing trait.

Deep-Sea Adaptations: The Role of Giant Squid Eyes

In the deep parts of the ocean, light is scarce. Giant squids live in this dark environment, and to navigate through it, they’ve evolved to have exceptionally large eyes. These eyes allow them to maximize the available light, providing them with a better chance of spotting food or potential threats.

In addition, bioluminescence is common in deep-sea creatures. This means they produce light, often in patterns or pulses. The giant squid’s big eyes also help it detect these faint light signals, enabling it to identify prey or predators from a distance.

The ability to interpret light signals in the ocean’s depths is crucial for survival. Different marine creatures produce varying light signals, each serving a unique purpose. Some use it to lure prey. Others to find a mate. And some even deploy light to distract or deter predators.

With eyes as large as theirs, giant squids can distinguish between these signals. Recognizing the right light patterns means they can respond accordingly, whether that’s by hunting, escaping, or interacting with other marine life.

The Threat of Sperm Whales

Despite their impressive size, giant squids aren’t the top predators in their environment. That title goes to sperm whales, which are known to hunt giant squids. For the squid, detecting these formidable hunters early on is crucial.

The disturbance caused by diving sperm whales often triggers light reactions from bioluminescent organisms. Giant squids, with their big eyes, can spot these disturbances from afar, giving them a warning sign and a chance to evade the approaching danger.

Evolutionary adaptation is all about improving survival chances. For the giant squid, having large eyes is a product of this. Their eyes are specialized tools, honed over millennia, to give them an advantage in an environment where visibility is minimal. The size of their eyes facilitates more light absorption, allowing them to see and interpret crucial light signals in the vast, dark expanse of their deep-sea home.

In conclusion, the giant squid’s enormous eyes are more than just a fascinating feature; they’re instrumental in its survival. This adaptation serves as a testament to the incredible ways life evolves to meet the unique challenges of different environments.

—WTF fun facts

Source: “World’s biggest squid reveals ‘beach ball’ eyes” — Sydney Morning Herald

WTF Fun Fact 12753 – The Rarity of Green Eyes

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We knew green eyes were rare, but they seem even more special knowing that only 2% of people in the world have them.

Green-eyed people are everywhere

But if your friend tells you their newborn has green eyes, they’re clearly seeing something different. All babies are born with some shade of brown or blue eyes. As their eyes are exposed to more light over time, their eye color begins to change into what their own unique genetics dictates. But this can take up to three years!

It may be no surprise that most people with green eyes can be found in Ireland, Scotland, and Northern Europe (or they’re descendants of people from that area). The red hair-green eye combo is pretty classic. However, anyone can technically have green eyes, including people who are Black, Arabic, Hispanic/Latino, etc.

If you were to guess the country with the most green-eyed people, would you choose Ireland? We would have. But, in fact, Iceland is the country with the largest population of green-eyed people. in fact, over 80% of Icelanders have blue or green eyes.

The myth of the Punnett square

Another interesting thing about eye color is that it’s not as simple as we learned in high school biology (remember Punnett squares?!). Genetics plays a role, but the contribution of different genes to our melanin cells (the cells that give our skin and eyes their pigment) is more complicated than we were taught. So don’t break out the paternity test as soon as you see an unexpected eye color. Even two parents with blue eyes can have a brown-eyed child!

Eye color is actually a polygenic trait (whereas Punnett squares would have had us believe it just took two genes and no more).

People with blue eyes have genes that produce the fewest melanin cells. Green-eyed people have more melanin in their eyes than blue-eyed people. But it’s the combination of that along with the presence of a yellow pigment called lipochrome that makes eyes appear green. – WTF fun facts

Source: “12 Mind-Blowing Facts About Your Body” — Newsweek

WTF Fun Fact 12746 – Owls Don’t Have Eyeballs

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Owls have eyes, of course. But owls don’t have eyeballs.

Instead, owls have eyes shaped like cylinders (with three eyelids!). Because of this shape, owls can’t roll their eyes around while keeping their heads still. That’s why they have to move their heads around too much to look around.

How do owls see without eyeballs?

According to the Office of Science & Society at McGill University: “Since moving their torsos would likely make noise that would alert their prey to their presence, owls have evolved to have necks that can spin up to 270° essentially silently.”

But why would an owl evolve to have eye rods instead of eyeballs? Wouldn’t it just be easier not to have to move your head at all in order to see to the side?

Well, perhaps, but the benefit of having eyes shaped like rods instead of balls is that not only does it allow them to see better in the dark but it’s the optimal shape for an animal with such a small skull.

The benefit of eye rods

As you may have noticed, nocturnal animals tend to have large corneas. That’s so any light can be collected more efficiently, allowing them to see in the dark.

As it turns out, these elongated eye tubes make it even easier for them to see the way they need to, even if they do have to make more movement in order to get a larger field of vision (also called binocular vision). Without moving their heads, their visual field is about 110 degrees (a human’s is 180 degrees, for comparison).

Binocular vision

Binocular vision also lets owls see objects in three dimensions (height, width, and depth). So, it turns out an owl’s eyes are pretty perfectly suited to its lifestyle.

While some believe all of this means that owls can’t see during the day because they’re blinded by too much light, that’s simply not true. Some owls can see even better than humans in the daylight as well, despite the lack of eyeballs.

At least you never have to worry about an owl giving you the side-eye. –WTF fun facts

Source: “Owls Don’t Have Eyeballs” — Office of Science & Society, McGill University