10 Things We Still Don’t Know About Our Oceans

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Oceans cover about 71% of Earth’s surface, and yet, there’s so much we don’t know about them. As we breach new frontiers in space exploration and prepare to launch for the stars, we’ve somehow still not managed to even scratch the surface of this vast realm right here on Earth. The deep sea, in particular, is one of the most understudied ecosystems on the planet. 

While there are many reasons behind that, the primary one is that even with our best tech, fully exploring the seas involves staggering, almost-impossible amounts of money, as well as advanced equipment that can withstand those pressures. The only people that have the means to do that are oil rig operators, or someone like James Cameron

Because of that, it’s a world full of the kind of mysteries and unexplained phenomena we love to discuss here. While we’re closer than ever to solving some of them, others – like bioluminescence – somehow get more mysterious the more we study them. 

10. The Ocean Floor

Even if most of us have never seen the bottom of our oceans, we imagine it to be largely flat – much like the kind of rocky floor you encounter if you swim a bit away from the shore. Swim far enough, though, and you’d find out that there’s nothing flat or uniform about the ocean floor at all. It’s made up of as many diverse terrain types as you’d find on land – if not more – with huge mountains, deep gorges falling into nowhere, underwater volcanoes, and everything else.

It’s also the most unexplored part of the ocean, as we’ve only ever been able to map about 15% of the ocean floor. It’s done by a sonar-based technique called multibeam bathymetry, and many modern ships are equipped with modern multibeam bathymeters to map out the ocean. However, most commercial ships only ply on designated sea routes, leaving a major part of it unmapped.

9. Bioluminescence

Bioluminescence has fascinated scientists and thinkers for a long time – recorded references to ‘glowing’ animals go as far back as Ancient Rome and Greece. Aristotle studied the phenomenon in detail and was the first to theorize, correctly, that these animals don’t use heat to produce light. We’ve since documented many animals – both on land and underwater – that have this ability, each with their own unique way of using it.

While it’s fairly well-understood for land animals, the phenomenon is far more widespread and complex in the oceans – especially in the deep sea. As we dive deeper and find even more animals that can produce light in a variety of ways, we find that it may just be an entire language and means of communication in a place completely devoid of light that we just don’t understand. According to a study, about 76% of all ocean animals have this ability, though we have no idea how most of them use it. 

8. Why Did Some Mammals Move Back Into The Ocean?

Every branch of life has its origins in the ocean, and most of us decided to stick with the decision to move to land. Except marine mammals like whales and manatees, who didn’t like the deal and chose to go back into the water.

Biologists have no explanation for why they did that, as it doesn’t make a lot of evolutionary sense. Early whales, for example, would have had a hard time even swimming underwater, as they’d long developed limbs and body types adapted for survival on land. They had no organs to help them survive underwater anymore, either – all marine mammals still have to use their lungs to breathe, much like all the other mammal species found on land. 

7. Mysterious Life Forms Under Antarctica

If we counted the most inhospitable ecosystems on Earth, the waters under Antarctica would definitely feature around the top of the list. It’s a vast region lying underneath an ice cover close to 5.3 million square miles in area, with no visibility and consistently below-zero temperatures.. Because of the hostile conditions, we’ve never been able to study it, until recently. 

During an exploratory dig by the British Antarctic Survey, researchers discovered that life under Antarctica isn’t just more diverse and vibrant than we ever thought, but also much more mysterious. While we’d always known that some known species can and do survive there – like fish, worms and some crustacean species – all of them are mobile predators or scavengers. This time, however, they found multiple species of filter-feeding organisms instead – creatures that require a consistent flow of food from above and sunlight to survive. 

The researchers have no idea how and why they live there, or even if it makes evolutionary sense to do so. Moreover, many of the species found during the survey have never been seen by science before

6. The Immortal Jellyfish

Jellyfish are one of the most diverse species of animals found in our oceans, with over 200 sub species each with its own unique features and adaptations based on its habitat. Some jellyfish species are also quite venomous, despite their often colorful and lively appearance. 

One jellyfish species, however, possesses an ability not found in any other type of life, not just other jellyfish. Turritopsis dohrnii, a jellyfish species originally found in the warmer waters of the Caribbean and Mediterranean, is the only organism we know of that can restore its cells back to their birth stage. The process is entirely involuntary, and only triggers during times of severe crises, like extreme starvation or injury. 


Turritopsis dohrnii is the only biologically immortal animal we know of – as opposed to being ‘truly immortal’, as they could still be eaten by predators and die – though we still don’t know how it developed this ability. Its cells are seemingly able to completely repair – and even reverse – the damage accumulated over time, which is what causes the rest of us to age and die. 

5. Narwhal Tusks

Narwhals are also known as the unicorns of the sea, because of their reclusive nature and poorly-studied, remote habitat. It’s a type of whale only found in the waters of the Arctic, and could be recognized by its long, pointed tusk that could grow up to 9 feet in length.

While there are many things we don’t know about the species, its tusk has long been its most fascinating and mysterious feature. It’s essentially an overgrown tooth only found in male narwhals, though scientists have never been able to figure out what it’s used for, or what evolutionary pressures made them develop it. Some theories say that it’s a survival tool that allows them to hunt more efficiently, though as female narwhals are known to survive longer than the males, that doesn’t seem to explain it. 

4. How Did Complex Life Evolve In The Deep Sea?

For billions of years, life only existed as microscopic, single-celled organisms in the depths of the ocean. Then, around 570 million years ago, something happened and complex life suddenly exploded in numbers, existing in the deepest parts of the ocean for nearly 15 million years before some of us left for land. All multicellular organisms today – from plants to horses to all marine animals – can trace their roots to that period.

That transition from simple organisms to complex life remains one of the – if not the – biggest mysteries of evolution. All complex forms of life are different from single-celled creatures on a fundamental level, and it’s not clear how – or even exactly when – we made the switch. One theory says that Archaea – an ancient single-celled life form that separated from other single-celled beings early on – is the missing puzzle. 

It fits into the larger question of why complex creatures evolved at all, as life had existed in the same simple form for billions of years with no apparent reason to evolve..

3. Cenotes

Cenotes are a kind of interconnected, natural wells found all over the Yucatan Peninsula in Mexico. Once considered sacred by the Mayans, it’s one of the most mysterious natural formations we know of. Apart from all the Mayan-era artifacts buried inside their depths, the cenotes themselves form a vast network of caves that has still not been properly explored.

Currently, there are close to 6,000 documented cenotes all over the Yucatan peninsula, though that’s only the ones we know of. Cave divers believe that there are many more of these sinkholes to be found all across the region, along with entirely new ecosystems and life forms we may have never seen before. 

2. Blue Whale Songs Are Getting Deeper

Blue whales aren’t just the largest animal on Earth today, they’re also the largest animal to have ever lived. They’re known for their songs, as every blue whale is capable of producing a unique frequency to communicate. While other whale species have this ability, too, blue whale songs are known for their variations and unique style. 

What we don’t know, though, is what they use it for. Marine biologists have tried to interpret songs produced by blue whales for a while now, though we can only guess what they mean. On top of that, the songs seem to be getting deeper every year. Blue whales have been consistently shifting their tonal frequency down since at least the 1960s, when we first started recording them, and we still have no idea why. 

1. The Surprising Diversity Of Life In The Deep Sea

The deep sea is the bottom-most layer of the ocean, roughly starting at a depth of about one mile, going all the way down to the seabed. It’s one of the most hostile places on Earth, with absolutely no light, an average temperature of about 39 degrees Fahrenheit, and immense levels of pressure most known animals can’t survive. 

Because of the extreme conditions, scientists used to assume that life would be sparse in the deepest parts of our oceans. Ever since we actually started exploring it, though, we’ve found that life in the deep sea isn’t just more diverse than we ever thought, but also more diverse than many habitable ecosystems found on land.

It’s a complete mystery to science, as according to all of our evolutionary theories, the deep sea shouldn’t be suitable for natural selection and development of diverse evolutionary traits. Moreover, we know almost nothing about the kind of animals and other creatures that live down there, or even how they interact with each other.


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