Creatures More Terrifying Than Megalodon Living In the Mariana Trench

Do Megalodon exist in the Mariana Trench? We may never know, but there are some strange deep sea creatures down there.

September 1, 2022・

10 min read

Have you ever wondered about what lies in the dark depths of the ocean? More specifically, I am talking about the deepest known point of the world’s ocean, known as the Mariana Trench.

What creatures are able to live there and, more importantly, are they any more frightening than the scariest creature that ever lived in the ocean, the Megalodon? Let's investigate a bizarre array of deep sea creatures that call the Mariana Trench Home. You might find them scarier than a Megalodon!

The Mariana Trench

The Mariana Trench is found in the western Pacific Ocean, 124 miles away from the crescent-shaped archipelago known as the Mariana Islands.

It’s a whopping 2550 kilometers long and 69 kilometers wide. To begin with, how deep is it? The Mariana Trench starts at a depth of 5,000 meters, but its deepest point is called the Challenger Deep and measures 10,994 meters. The 8,848-meter high Mount Everest can be placed in the Mariana Trench and there’d still be over 2,000 meters to fill.

Given its unique geographic features, the Mariana Trench presents several factors that make it hard for life to exist. For one, sunlight cannot reach these depths. The area is shrouded in complete darkness, making it difficult for all animals to traverse the trough.

Secondly, there’s no algae or plants to eat down there because there’s no sunlight to feed them. Third, given its lack of sunlight, it’s very cold down there with a temperature range of 4 degrees to negative 1 degrees Celsius.

And finally, the pressure in the Mariana Trench is at eight metric tons per square inch, which is nearly 1,200 times more than the average atmospheric pressure at sea level.

That’s like bearing the weight of a fully loaded truck on your head while stuck inside a refrigerator. As demonstrated below, to survive given these extreme factors, the creatures in those depths have evolved in some bizarre ways.

Fangtooth

First up is this creepy fish dwelling in the Mariana trench known as the Fangtooth. It’s a beryciform fish, which means that it’s carnivorous and lives in deep, nocturnal habitats. It got its name for how big its fang-like teeth are.

In fact, this creature had the largest teeth of any fish relative to its body size. Two of its fangs are so long that the Fangtooth evolved two sockets beside its brain to contain them when its mouth is closed.

Even so, its teeth are so large, that it can’t fully close its mouth. Its large teeth are thought to be an advantage in dark isolated depths where anything encountered must be preyed upon. Even if its prey turns out to be larger than itself, its disproportionately large teeth and mouth will prove useful.

Basically, it moves around and hopes that what it bumps into is food. It’s terrifying for sure, but at an average length of 16 centimeters, it’s actually too small to severely harm a human being.

Juvenile fangtooths stay at a depth ranging between 200 and 2000 meters, but adults can go much deeper, reaching as far as 5,000 meters. Without light to locate its prey, it uses contact chemoreception. It has receptors that respond to chemical substances given off by potential prey upon physical contact.

Apart from the small but freaky fangtooth, there are other creatures such as the Mariana snailfish.

There is also the benthic comb jelly.

Both these creatures are known to survive in waters as extreme as the Mariana trench, but none of them is as terrifying or bizarre as the megalodon, an extinct shark species that averaged a frightening length of 10 meters. This is about the same as a T-Rex.

So, to find creatures as scary as the megalodon that could live in the Mariana Trench, we have to go back in time to the prehistoric period when sea levels, and the geography of the world were vastly different. After all, only four brief descents have ever been made to discover what lives in the Mariana trench, which means all we can do is guess about what lives down there.

We still have 95% of the ocean left to explore, and since the Mariana trench is over 95 thousand square miles, who knows? We might even find some deep-sea creatures we previously thought were extinct. Let’s explore the possibilities now.

Liopleurodon

First up is a carnivorous marine reptile that is probably the most frightening creature that ever roamed the seas. At over 6 meters in length, creatures of the liopleurodon genus were apex predators that ruled the waters during the middle and late periods of the Jurassic era.

Could liopleurodon have lived in the Mariana Trench millions of years ago?

Its physical features suggest so. First, it was strong enough to swim long distances. It had four mighty limbs that worked like paddles to move its body. Researchers noted that the reptile’s propulsion method wasn’t exactly the most efficient, but it allowed the carnivore to accelerate and successfully ambush its prey.

Plus, studies of the liopleurodon’s skull suggest that it might have used its nostrils to identify distinct smells and locate their source. This suggests it lived in deeper waters like the Mariana trench, where a lack of visibility didn’t affect its ability to hunt prey.

In addition, liopleurodon had eyes designed to ambush its prey from below. Their eyes were pointed upwards to see the silhouette of their prey.

It’s true that sunlight no longer reaches the Mariana trench, but some deep-sea creatures have developed bioluminescence, allowing them to emit light to lure prey, attract a mate, or deter other creatures. So apart from locating its prey in the dark by scent, the liopleurodon also likely hid in the depths below its bioluminescent prey and waited for an ambush.

Hainosaurus

A second prehistoric monster that may have well lived in the Mariana Trench is this giant marine Mosasaur known as a Hainosaurus, which scientists think grew up to 12 meters long – about the same length as an average megalodon.

And with teeth like that, it would have even scared a megalodon. Scientists say that it lived predominantly in the shallow waters of Europe and North America. However, there’s also some evidence it may have also roamed the depths of the Mariana Trench because of how it had a wide variety of prey.

Though we’re unaware of most creatures that roamed or are roaming the Mariana Trench, certain sharks and cephalopods have been identified to live in similar deep-water habitats.

Presently, goblin sharks can live up to 1300 meters below, while frilled sharks can reach depths of 1500 meters. The giant squid, a cephalopod, has been found at a depth of over 1000 meters. The leatherback sea turtle, on the other hand, has been found at a depth of 1,200 meters. At the same time, a Hainosaurus specimen was found to have eaten a giant turtle in Belgium.

These depths are approximately the same as the starting depth of the Mariana Trench, but it’s possible that prehistoric sharks and cephalopods traveled down much further. And if they did, the Hainosaurus may have adapted to the conditions of the habitat of their prey.

It even had large nostrils, which means it must have lived in an area where having a better sense of smell was beneficial. Its big nostrils would have helped it locate food in deep waters such as those of the Mariana trench.

Helicoprion

Up next, here’s a shark-like fish that lived 290 million years ago and measured about six meters long.

Helicoprion could have lived in the Mariana Trench for several reasons. First, its closest living relatives are chimeras, with most species in this order living in depths of up to 2,600 meters. Since chimeras thrive in these depths, perhaps the Helicoprion lived even deeper.

It’s a particularly mysterious creature, with scientists still researching how it behaved and what its anatomy was like since we haven’t yet discovered a complete fossil of it. Still, it's thought to have lived around the location of the trench, so there’s a good chance the seabed around that location is the only place we’ll find a complete fossil of it.

Furthermore, its diet is similar to the Hainosaurus’s since it also ate fish and cephalopods. You see, researchers always wondered what its spiral-shaped teeth were used for and where it developed. It wasn’t until 2013 that a skull of the prehistoric creature was scanned to reveal the truth: The Helicoprion’s tooth whorl was located inside its lower jaw.

If it hunted down a deep-sea fish or squid that lived in the Mariana Trench 290 million years ago, it would have likely sliced into its prey’s body using its serrated saw-like teeth. When the Helicoprion then closed its lower jaw, the teeth whorl inside would have moved backwards not only to slice its prey but also to move it to the back of its oral cavity to begin digestion.

The fact that a complete fossil of the Helicoprion has yet to be discovered means the mystery of this creature is yet to be fully resolved, but I for one can’t wait to find out more.

Odobenocetops

Another frightening deep sea creature worth nothing is the Odobenocetops; a whale that became extinct before the Pliocene epoch began about 5.3 million years ago.

It measured about 4 meters long and weighed up to 650 kilograms. It’s not the biggest marine mammal, but it’s hefty enough to be feared by the many small creatures in the deep. There is a lot to suggest it may have lived in the Mariana Trench. The first clue is how whale species alive today are capable of venturing into the deep.

The Sperm whale, for example, is known for diving over 2200 meters down. Likewise, Cuvier’s beaked whales have traveled nearly 3,000 meters down, the deepest recorded dive by any mammal. The pressure is already so great in these depths that a creature’s lungs could collapse and they could suffer from convulsions.

Yet whales are willing to go there to find food such as deep-sea squid. The secret here is that marine mammals such as whales have flexible, foldable rib cages that keep air pockets like the lungs protected.

The mystery remains, however, of how these whales prevent convulsions caused by a disorder known as high-pressure nervous syndrome. If whales today have a physical feature to counter the risk of highly pressured deep waters, the same could have been true for the Odobenocetops.

Another clue as to whether the Odobenocetops went down as deep as the Mariana Trench is how its snout and neck evolved. The whale’s snout resembles that of a walrus, which indicates it was probably a bottom feeder that ate mollusks by sucking them out of their shells.

That bodes well for our thought experiment, as scientists have observed mollusks in the Challenger Deep; the deepest point of the Mariana Trench, at a depth of 11,000 meters. Also, its neck is flexible, allowing it to move its head about 90 degrees to have a better view of its food below.

Apart from that, we don’t know much more about the Odobenocetops, but scientists think it may have used its tusks not only to find any nearby prey but also to stun them, similar to how narwhales today use their tusks to stun Arctic cod.

All in all, the Mariana trench remains a mysterious, elusive habitat we may never get to fully explore. So, the possibilities of strange life down there are endless. If you enjoyed exploring this topic, you might want to read about the largest sea creatures ever known. Thanks for reading!