Top 10 Mysterious Creatures That Live in the Deep Sea

There’s something truly alien about the world at the bottom of the sea. Welcome to WatchMojo and today we’ll be counting down our picks for the top 10 mysterious creatures that live in the depths of the ocean.

For this list, we’re looking at the good, the bad, and the ugly you can find trawling the seafloor.

We’ve only filmed anglerfish in their natural habitat a handful of times, so for many years didn’t know exactly how they behaved. But they’re just as creepy and weird as their appearance would have you believe. Named for the bioluminescent lure that hangs down in front of their teeth, you may be surprised to hear that only half of all anglerfish have this distinctive trait: the females. Males are tiny and attach to their larger, frightening counterparts to mate, eventually dying in the process. For this reason, anglerfish are considered “sexually parasitic,” and deadly predators to boot.

There are many different species of shark that live at all depths of the ocean, some around tropical reefs and others, like the sixgill shark, far below the surface. One of the oldest shark species in the world, the bluntnose sixgill is practically prehistoric – and it’s also enormous: they can grow up to twenty feet long on average. But these sharks are far from big, friendly giants. They hunt a wide range of prey including squid, crabs, and even other types of shark. Luckily, because they live thousands of feet down, you’re unlikely to run into one of these monsters while swimming.

This small cephalopod is as misunderstood as it is interesting. The vampire squid gets its name from its spooky appearance: the webbing between its arms looks like a cloak and it has red, bioluminescent eyes. Because of this, it was given the Latin name “Vampyroteuthis infernalis,” which literally means “vampire squid from hell.” But from feasting on the blood of the innocent, it actually eats bits of detritus that float into its mouth. Most interesting of all, however, is that rather than spit out a cloud of ink to defend itself like other squids are famous for doing, the vampire squid expels a glowing liquid to confuse predators in the lightless depths.

You’ve probably seen viral pictures of pink, sad-looking blobfish after they’ve been pulled out of the water, but they look entirely different if you see them in their natural environment. Because they live so far down where the pressure is so intense, they don’t need any muscle mass to keep their shape. This means that when you take them out of the water, they depressurize and turn into the distinct “blobs.” They’re actually less dense than the water they swim through, which enables them to float above the seafloor at crushing depths that would be too much for many other creatures to bear.

At roughly a foot long, the pacific viperfish may not be the giant, deadly predator you’re used to hearing about – but this doesn’t make it any less frightening. There are nine species of viperfish, all named for their protruding, razor-sharp teeth, and all violent and fast, but the pacific variety is the scariest. They’re specially adapted so they can crash into things and bite them at high speeds without doing any damage to themselves. But this isn’t actually how they hunt; like the deep-sea anglerfish, the viperfish also has a bioluminescent lure that hangs down and entices prey to come closer so it can strike.

Up until as recently as 1977, we didn’t have a clue that creatures like giant tube worms existed – and they were actually discovered completely by accident by an expedition intending to study underwater volcanoes. The worms can grow upwards of 6 feet long and only live around hydrothermal vents, meaning they’re capable of withstanding extreme temperatures and dangerous chemicals that kill other forms of life; the thermal vents can heat up the water around them to over 600 degrees Fahrenheit. Even weirder, the worms have no digestive system. Symbiotic bacteria live inside their bodies in a unique organ, a trophosome, and provide the carbon they need to eat.

If you thought the viperfish had a nasty set of teeth, wait until you get a load of the fangtooth fish, which has the largest tooth-to-body ratio of any creature in the entire ocean. Its pointed teeth are so big it has specially adapted sockets in its head for the teeth to sit in when it closes its mouth – though, even with this, the fangtooth still can’t shut its jaw completely. They’re known to hunt small fish, shrimps, and squid, and have some bioluminescence like most creatures dwelling at these depths – up to 6500 feet down. But they’re far from apex predators, and even common tuna have been known to hunt them.

These deep-sea dwelling crustaceans are the biggest species of crab in the world and have the largest leg span of any other arthropod. It’s their enormous legs that give them their name but, unlike spiders, they actually have ten limbs. They’re also capable of withstanding extreme pressure and periodically shed their shells in order to grow. But don’t worry, as big and creepy as these creatures are, they’re notably gentle and pose no threat to humans – and they’re also a common feature in aquariums and seafood restaurants around the world. However, current spider crab populations are threatened by overfishing as they’re considered a delicacy.

Sharks have been roaming the oceans for millions of years, and predatory deep-sea sharks are the ones that have evolved the least, simply because they don’t need to. That’s why the frilled shark, which is found in oceans around the world, is often nicknamed a “living fossil”; it more closely resembles extinct sharks than others living today. The frilled shark grows to be over 6 feet long and has roughly 300 teeth in its mouth, making it a formidable foe. They’re even known to eat large squid and other sharks. But, mysteriously, the squids it eats are much more mobile, meaning we don’t actually know how this slower predator manages to catch them.

Before we unveil our top pick, here are a few Honorable Mentions:

Giant Isopods
Because they’ve got four sets of jaws.

Chimaeras
Because they’re also called “ghost sharks.”

Scotoplanes
Because they’re nicknamed “sea pigs.”

Barreleyes [aka Spook Fish]
Because their heads are transparent.

Comb Jellies
Because they’re made of fairy lights.

Though specimens of this unusual species have been caught for decades, it wasn’t until the 1990s and 2000s that we were able to film and properly identify them. Their most distinct characteristic is their enormous arms, which are over twenty feet long. But unlike other cephalopods which move through the water by expelling water, bigfin squids have enormous fins on their mantles – which is where their name comes from – and this is how they swim. Scientists believe the arms and tentacles are dragged along the seafloor and used to catch food, though none has ever been observed feeding, so this remains speculation.