From an ancient fish thought to be extinct until a fisherman accidentally caught it, to terrifying creatures that haven’t changed in billions of years—these are the mysterious sea creatures that scientists once thought were gone forever.
Imagine accidentally catching a fish that was believed to have gone extinct 66 million years ago. That’s what happened in 1938 when a South African fisherman accidentally caught an ancient fish called a coelacanth. Scientists once believed the fish had disappeared along with the dinosaurs, making the discovery a shocking find.
This “living fossil” has remained virtually unchanged for hundreds of millions of years. Unlike regular fish, coelacanths have bony fins that resemble primitive legs, and some researchers believe they may have been an evolutionary bridge between marine life and the first vertebrates to walk on land. What’s even more bizarre is that they don’t swim in the usual way, but move through the water in a “walking” manner, using their fins rhythmically similar to quadrupeds. Not only that, their scales are also bioluminescent, creating a magical blue light.
Until now, the coelacanth is still a rare species, found only in the deep waters off the coast of Africa and Indonesia. They have a very long lifespan, can live up to 100 years or more, and especially, their gestation period lasts up to 5 years—a record in the animal world.
**Strange sea monsters from the bottom of the ocean**
If there was a list of scary fish in horror movies, the Lancetfish would definitely be at the top. They have long bodies like silk ribbons, dorsal fins that extend almost the entire body, and sharp teeth that are exposed even when their mouths are closed. One of the most bizarre features of this species is its almost… non-existent digestive system. When scientists examined the stomachs of knifefish, they found that the prey inside remained intact, almost undigested. This gives them the appearance of “zombie” creatures, always eating but never actually digesting their food.
Knifefish are also hermaphrodites, meaning they possess both male and female reproductive organs. Another mystery is that despite living in the deep sea, they are often found washed up on land intact. What brings them to the surface? Is it an unknown environmental factor or is there something more sinister lurking at the bottom of the ocean?
**Unknown Sharks**
In 1976, scientists accidentally discovered a giant shark species that had never been recorded—the megamouth shark. This shark can grow up to 5.5 meters long and has a giant mouth that looks like it came out of a fairy tale. Unlike most sharks that hunt with speed or power, the megamouth shark simply swims slowly with its mouth wide open, filtering plankton and jellyfish from the water, similar to a whale.
The most terrifying thing about megamouth sharks is not their size or hunting style, but the fact that they have remained completely hidden in the ocean for millions of years without anyone knowing. Since the first discovery in 1976, only a few dozen individuals have been recorded, proving that the ocean is still full of undiscovered mysteries.
**Ancient creatures that still exist**
The Nautilus is one of the rare creatures that has retained its form from half a billion years ago, surviving many mass extinctions. Their shells follow the Fibonacci sequence—a mathematical pattern that appears in galaxies, storms, and even human DNA. Is this just an evolutionary coincidence, or is there something more mysterious?
Unlike their distant relatives, the octopus and the squid, nautiluses lack high intelligence, but they do have an incredibly efficient buoyancy system that allows them to float slowly through the water as if they were floating in space. Their large eyes help them detect even the slightest movement in the dark, making them masters of survival in the deep.
**Weirdest Predators**
The Goblin Shark is one of the strangest-looking creatures in the ocean, with a long snout, pinkish-gray skin, and a jaw that can be extended like a harpoon to grab prey. The shark was first discovered in the 19th century, but it wasn’t until the development of deep-sea fishing technology that humans had the opportunity to observe it more regularly.
Goblin sharks don’t chase prey, but instead use electromagnetic sensors on their snouts to detect signals from creatures lurking in the sand. When they spot prey, their jaws dart out at such a speed that only high-speed cameras can capture it.
Do Sea Monsters Really Exist?
Many people think that the Loch Ness Monster or other mysterious creatures in the ocean are just myths, but species like the Frilled Shark make us think again. They have eel-like bodies, sharp teeth, and have existed for over 80 million years without changing much.
Then there is the Giant Squid, a creature that was considered a legend until evidence of their existence was recorded in the early 2000s. They can grow to over 12 meters long, possess huge eyes for seeing in the dark, and tentacles that can capture prey at incredible speeds. Battles between giant squid and sperm whales—their natural predators—have left mysterious scars on whale carcasses that have washed up on shore, proving that battles on the seabed still take place in ways that humans have never witnessed.
The deep sea still holds many unsolved mysteries, and who knows, maybe one day we will discover creatures even more terrifying than what we already know.
