Unsolved Mysteries of the Deep Sea


The deep sea has always been a place of perilous mystery for humankind. Even if it has been a while since we left the oceans for a better and drier life outside, the fear of what lies beneath the depths still exists somewhere inside all of us. 

Even today – with all of our best technology – we know scarily little about the deepest parts of our oceans. Exploring it is next to impossible, thanks to the immense – almost unimaginable – pressure at those depths, as well as absolute darkness. 

What we do know, though, is that despite the inhospitable conditions, the deep sea is teeming with animals and plants – and everything in between – that have changed little in the course of their evolution. Or as far as we can tell, anyway, as a large chunk of the deep sea still remains unexplored and hidden from the scientific eye.

8. Everything About Jellyfish

Most people are no strangers to jellyfish, as they thrive in waters around the world. They’re not particularly noteworthy, except for their weird body structure and unnecessarily high amount of sting power. As long as they stay away from us, most of us never even think about them.

If you read up on them, though, you’d realize that jellyfish – a broad umbrella of marine creatures – around the globe are silently trying to take over the world. We’re not exaggerating; jellyfish populations have been mysteriously rising in many independent regions. Explanations range from global warming to the sudden abundance of oil drilling platforms – thus giving them more place to thrive – though no one can really say for sure. 

That’s not all: jellyfish are generally an immensely understudied part of marine life, too. They reproduce in a manner completely alien to anything we know of. One species is even immortal, or as immortal as one can get, anyway. And yes, it’s also silently increasing its population, much like most of the other jellyfish species. They’re also the oldest type of animal we know of, as well as one of the most mysterious.

7. The Inexplicably High Biodiversity In The Deep Sea

For an average person, it’s difficult to imagine how inhospitable some parts of the ocean are. Beyond a point, things like high pressure and no visibility don’t mean much to most of us. That’s why it’s difficult to imagine any type of life being able to survive at those depths at all. From everything we’ve gotten to know about the deep up to now, though, life in the deep sea is much more diverse and numerous than any other ecosystem we know of.

The deep sea harbors the largest fraction of biodiversity in the world, and we still don’t know how that came to be. A big chunk of that is micro-organisms that have evolved over millennia to survive in some of the harshest conditions found on Earth. There are quite a few big animals, too, including the biggest invertebrate we know of: the colossal squid

6. The Underwater River

Anyone who has traveled to Yucatan Peninsula in Mexico would gladly tell you all about its unique topography and numerous natural attractions. Yucatan is known for cenotes: natural water-filled holes in the ground of varying shapes and sizes, leading to one of the most extensive – and under-explored – cave systems in the world. 

While there’d be many more mysteries waiting to be discovered in the depths of some of the deeper cenotes, one of them – Angelita – is home to a particularly peculiar one. If you dive to about a 100 feet, you’d see a whole river flowing under the bright blue water. It’s not rocket science really – the salty groundwater is heavier than the fresh water closer to the surface. The difference in densities causes the river beneath to seem like an underwater river. It’s also quite high in biodiversity, though we still don’t know if it’s a unique phenomenon or if these rivers are found across the cave systems. Most cenotes have distinct, almost-unique ecosystems of their own, though due to inaccessibility and lack of funds, most of them remain unexplored.

5. Entirely New Type Of Hydrothermal Vents

Venture too far into the depths of the ocean, and you may start finding things that you’ve never seen before. That’s no exaggeration; the ocean floor is still overwhelmingly unexplored, and we still find things that are entirely new to our current understanding of underwater life. Take the entirely new type of hydrothermal vents found in the deep sea of the Caribbean that may as well be an alien type of ecosystem.

Hydrothermal vents are important because they’re home to some of the earliest and most diverse types of life found on Earth. Studying them is key to answering some of our biggest questions, as we’ll come to in a bit. Finding an entirely new one opens up a slew of doors for our researchers, though it’d take a while before we could completely decipher it.

These vents are unlike anything we’ve seen before, complete with completely different type of minerals and chemistry than any other observed vent system. It also proves that the ocean floor isn’t static and unchanging as we imagine it to be, but is constantly subject to the massive tectonic forces of the Earth.

4. The Mystery Of Bioluminescence

Almost everyone knows that the ocean is full of organisms with the ability to produce – and even control – light. It’s one of the most unique biological traits found in nature, though it makes sense that in the absence of any sound or light, deep sea creatures must have developed some luminescence to look around. 

As more and more research is finding out, though, bioluminescence may be a much more important part of life in the deep sea than we ever thought. Over 76% ocean creatures have this ability, though we don’t quite understand how all of them use it. Many deep sea creatures – including microbes – have been observed using it to communicate and find food. It may just be a whole new language of the deep sea that we simply don’t understand yet. Its evolution remains a mystery, too, including the fact that it’s found almost exclusively in the lower, simpler branches of the tree of life. 

3. Whatever This Thing Is

Because of its inaccessibility, the deep sea is almost impossible for us to even start to explore. In fact, most of the actual exploration of deep sea creatures is done by the oil drilling industry, providing us with some of the only pictures of – and a much needed glimpse into – life found at the bottom of the ocean.

While it’s great to occasionally discover a new type of animal, sometimes that animal turns out to be so scary that we wished we had never discovered it. Case in point: the massive and mysterious squid-like thing recorded by oil wells in the Colombian Southern Caribbean.

We really have no idea what that is without a better look, though as far as we can tell, it may be a specimen of the Magnapinna family of squids. It’s a ridiculously under-studied species, as a live member has never been captured or fully observed in the wild. That’s probably for the best.

2. The Mystery Of Life Itself

Of all the mysteries of the deep sea, the biggest one has always been – and probably will always be – the mystery of life itself. Of course, we’d never be able to reliably answer that question, as it’s impossible to replicate – or even know of – the conditions on the planet at the time of the first living things. Some research, though, does point toward the possibility that life may not have come in the form of an asteroid from the sky at all, but from the deepest parts of our oceans.

The above-mentioned hydrothermal vents in the deepest pockets of our oceans aren’t just full of life, but life that’s not seen anywhere else on the planet. These vents are home to fauna and microbes that need no light to survive, or even oxygen in some cases. According to some scientists, hydrothermal vents may have been the perfect place for early life, and simple metabolic reactions in those vents may have birthed the first living things. While we may never fully find out, exploring the deep sea may just be the key to filling the missing gaps in our evolutionary history. 

1. The Ocean Is Ridiculously Unexplored

When we talk about how unexplored the oceans really are, we aren’t really able to instinctively estimate what that means. In the age of spaceships and almost futuristic exploration equipment, ‘unexplored’ isn’t something we associate with any part of the planet, as we’re on to more important exploration frontiers, like space

That’s why it comes as a surprise to most people that the deep sea is far less explored than space, which could be the case for a long time to come. In fact, we’ve been to space over 550 times now. The deepest point of the ocean was only touched in 2019, and only three other people have ever reached those depths. By some estimates, around 95% of the oceans and 99% of the ocean floor lie unexplored.

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