The Mariana Trench is the deepest oceanic trench on earth. The lowest point is known as the Challenger Deep, and it is believed to have a maximum depth of 36,037 feet / 10,984 meters below the ocean’s surface.
The first manned exploration occurred in 1960 when the bathyscaphe “Trieste” descended into the Western Pacific Ocean with two people, Jacques Piccard and Don Walsh, to 35,797 feet / 10,911 meters inside the Challenger Deep area.
The various manned and unmanned dives to the Pacific Ocean seafloor have studied numerous Mariana Trench animals, many of which were previously known to science. While fascinating, we’re going to see that some of these creatures are also pretty scary-looking.
What Creatures Live In the Mariana Trench?
At the bottom of the Mariana Trench, the water pressure is more than 1,071 times that found at sea level, so it really is impressive that there is any life there at all.
As well as the high pressures, the creatures in the trench live with a complete absence of natural light in temperatures ranging from 34 to 39 °F / 1 to 4 °C.
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The most common life found at the bottom of the trench are microorganisms, and scientists have identified over 200 different species from mud samples they have collected.
Creatures found in large quantities include saucer-sized, single-celled xenophyophores, which feed on sediment. There are amphipods, which are large shrimp-like scavengers, and small sea cucumbers called holothurians. Other animals that have been discovered include bacteria, crustaceans, and octopuses.
Organic food is scarce at the deepest point of the Mariana Trench, and so many microbes feed on chemicals, including hydrogen and methane, released underwater.
Scientists believe that the maximum depth for fish to live is about 28,000 feet / 8,500 meters due to the extreme pressure. So, while you might not find fish in the deepest parts of the Challenger Deep, many species have been found in the shallower areas of the trench. In 2014, the mariana snailfish (Pseudoliparis swirei) was observed at a depth of about 26,000 feet / 8,000 meters.
15 Strange and Scary Mariana Trench Animals
The depths of the Mariana Trench are home to some of the strangest creatures ever discovered on planet earth. Real Mariana Trench animals look like they could be from science fiction, and some would even look at home in horror movies. Let’s take a look at some of the most fascinating and frightening deep-sea animals found in the trench zone.
1. Deep-Sea Dragonfish
Our first Mariana trench creature is the deep-sea predator, the dragonfish (Stomiidae). These are a family of fish with especially large teeth for their size. Dragonfish are found at depths between 700 to 6,000 feet / 213 to 1,828 meters.
Deep-sea dragonfish use bioluminescent photophores along their sides to create a reddish light to attract prey and mates. They also have a protruding photophore on their chin which they use as a fishing pole to entice potential meals.
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2. Black Seadevil Angler Fish
Thanks to its role in the Disney favorite Finding Nemo, the Black Seadevil angler fish (Melanocetidae) is known to many people.
With its strangely shaped body and sharp teeth, this fish definitely counts as a scary inhabitant of the deep ocean. Angler fish get their name from the bioluminescent lure called an esca which sticks out from their head and is used to attract prey.
Seadevil Angler fish look frightening, but they aren’t particularly large. The female reaches about eight inches / 20 centimeters, while males are only about one inch / 2.5 centimeters. However, thanks to their gaping jaws, they can swallow meals much larger than their own size.
3. Dumbo Octopus
With their floppy ears, the dumbo octopus (Grimpoteuthis) falls into the category of strange rather than scary. Although scientists found the first samples in 1883, it wasn’t until the 1990’s that a live dumbo octopus was seen underwater from a submersible.
Dumbo octopus are pelagic umbrella octopuses measuring about 10 inches / 25 centimeters. They have a gelatinous body that allows them to live at extreme water depths below 3,300 feet / 1,000 meters, and the deepest observed live specimen was found in 2020 in water 22,824 feet / 6,957 meters deep.
The so-called Dumbo ears that give the octopus its name are, in fact, fins that the animal uses to swim. Its eight tiny tentacles are used to help the octopus maneuver or to walk along the bottom.
Dumbo octopuses like to eat worms, amphipods, copepods, isopods, and other crustacea. It pounces on its prey and swallows them whole to be slowly digested inside its body.
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4. Zombie Worms
The very name Zombie conjures images of the undead praying uncontrollably on their victim’s brains. However, the zombie worm (Osedax) is a living creature, and it likes to eat the bones of deceased whales that have fallen to the ocean floor.
Zombie worms drill into the bones using special root tissues which secrete acid and use symbiotic bacteria to digest the proteins and lipids they contain. They have feathery plumes that wave in the water and are used as gills to breathe through. These can be seen sticking out of the holes that the worms have made in the bones.
The worms were first discovered in 2002, living on the remains of a gray whale found at a depth of 9,491 feet / 2,893 meters. These acid-producing scavengers certainly sound scary enough to us, although they don’t pose much of a threat unless you’re a whale carcass in the deep ocean.
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5. Mariana Snailfish
As we’ve already mentioned, the mariana snailfish holds the record for the deepest fish captured on the seafloor. This strange-looking fish is believed to exist in the Mariana Trench at depths ranging from 20,335 feet / 6,198 meters to 26,495 feet / 8,076 meters.
The snailfish looks a little like a tadpole and has loose skin instead of scales. It uses its small teeth to feed on small crustaceans that it finds on the bottom. Fully grown, the fish reaches about 11 inches / 28 centimeters in length.
There aren’t thought to be many predators for the snailfish, and it appears to exist in the trench in relatively large numbers. Like many inhabitants of the deepest depths, the snailfish is thought to be completely blind and has developed its other senses to find food.
6. Benthocodon Jellyfish
The benthocodon is a deep-water jellyfish with a spectacular alien-like appearance. They are small in size and have an intense red coloration, unlike most jellyfish that are clear.
The jellyfish spend their lives swimming deep in the water column, using their thousands of tiny tentacles to move. It is believed that the red bell of their body hides the bioluminescent light from the creatures that the animal has eaten. This enables it to keep its camouflage in the dark and remain hidden from prey and predators.
7. Deep-Sea Hatchetfish
The deep-sea hatchetfish (Sternoptychinae) get their name from their thin blade-like body shape, which resembles a handheld hatchet.
The fascinating and strange part of this animal is how it uses bioluminescent light as an ingenious method of camouflage. The hatchet fish has photophores along their bellies and sides, which they can use to replicate the low amounts of light coming from above. This hides their silhouette and makes them nearly invisible to predators or prey approaching them.
8. Frilled Shark
The frilled shark (Chlamydoselachus) would definitely frighten you if you came across one on a swim or scuba dive. This strange wide-mouthed, eel-like shark has been given the name “living fossil” thanks to its odd appearance, which hasn’t changed over millions of years.
Frilled shark hunt like snakes or eels and will lunge to capture their prey whole inside their hinged jaws. There are more than 300 needle-like teeth inside the scary-looking mouth of the frilled shark that are more than capable of dealing with its diet of smaller sharks, fish, and cephalopods.
9. Vampire Squid
The frighteningly named vampire squid (Vampyroteuthis infernalis) has evolved to exist in depths of at least 2,000 to 3,000 feet / 600 to 900 meters.
The squid use filaments on their eight arms to detect and capture food, which you might not expect from their name. Instead, this comes from its order name Vampyromorphida of which it is the last remaining member. The squid does have a deep red color and bioluminescent lights, so it does have a somewhat scary appearance.
When threatened, the vampire squid curls its arms upwards around its body, sticking out small spiky projections. It can squirt bioluminescent liquid, which sticks to its attacker. Not only does this dazzle the predator and allow the squid to escape, but it can also make them more visible and liable to attack themselves.
10. Telescope Octopus
The telescope octopus (Amphitretus pelagicus) is almost entirely translucent and colorless and is often called the ghost octopus due to its ability to hide in the ocean’s depths.
The octopus gets its name from its unique rotating tubular eyes. The strange-looking animal reaches about eight inches / 20 centimeters in length, and it spends its time drifting vertically in the water column looking for food.
11. Barreleye Fish
The barreleye fish (Opisthoproctidae) is also known as the spook fish and have unusual barrel-shaped eyes that point upward to look for their next meal.
The head is covered by a transparent dome and has large nostrils often mistaken for eyes ahead of its actual eye barrels. The dome protects the fish from being stung when it eats jellyfish and gives it a genuinely science-fiction-like appearance.
Barreleyes will float along in the water, waiting for food to come to them. They have large fins that help them keep their position and can quickly strike when the time comes.
12. Ping-Pong Tree Sponge
This strange-looking creature (Chondrocladia) is a carnivorous sponge dotted with hook-covered spheres that trap its prey.
Small crustaceans drift past and stick to the surface of the balls. The meal is then absorbed inside to be slowly eaten alive.
13. Comb Jellies
Comb jellies (Ctenophora) are covered with bioluminescent combs that give their gelatinous bodies a beautiful shimmering rainbow-colored appearance. There are hundreds of different species found in the depths of the Mariana Trench, and they can range in size from fractions of an inch (a few millimeters) to five feet / 1.5 meters long.
Comb jellies feed on plankton, crustaceans, and other comb jellies. They have two tentacles to pull food into their mouths, where enzymes and muscular contractions digest it. What isn’t needed is impolitely regurgitated back through their mouths into the water.
14. Pink See-Through Fantasia
This oddly named animal is a translucent sea cucumber (Enypniastes eximia) with pink-colored skin through which it is possible to see its internal organs.
The cucumber can swim in the water above the ocean bottom and feed on benthic sediment. Unusually the pink see-through fantasia uses bioluminescence on their skin to deter predators. If attacked, the luminescence coats the predator leaving them glowing and at risk of attack from other animals.
15. Fangtooth Fish
The Fangtooth (Anoplogastridae) is said to have the longest teeth of any animal found in the ocean in relation to its body. With its large jaw and ugly-looking skin, this is without a doubt one of the most frightening looking deep-sea fish.
The maximum size of the fish is about 6 inches or 15 centimeters. However, the large jaw and incredible teeth allow the Fangtooth to enjoy much larger fish or squid that it comes its way.
Fangtooths don’t have good eyesight and are said to find their food by detecting their movements in the water.
What Is the Scariest Animal in the Mariana Trench?
While we’ve considered 15 different strange and scary animals, one more stands out as the most terrifying of all the Mariana Trench monsters.
The Goblin Shark – The Scariest of All Deep Sea Animals
The goblin shark (Mitsukurina owstoni) is a rare shark that can reach over ten feet / 3 meters in length. It has odd pinkish skin and a long, flat snout that contains a protruding jaw filled with large numbers of extremely sharp teeth.
Goblin sharks uses sight, smell, and electro-detection to hunt prey. When it’s time to strike, the shark ambushes its victim, and the snout extends dramatically to reveal the jaw.
The jaws snap forward like a slingshot and engulf the prey in their bite. Luckily the preferred food is fish such as dragonfish or cephalopods. However, we definitely wouldn’t want to meet one of these scary-looking beasts underwater.
Is Megalodon in the Mariana Trench?
The megalodon (Otodus megalodon) is an extinct shark that is said to have grown to an incredible maximum of 67 feet / 20 meters.
Some people wonder if the list of Mariana Trench creatures could include this incredible animal. However, scientists are convinced that the megalodon shark has been extinct for thousands of years. Such a large animal would need vast amounts of food to survive, and while life is abundant in the Mariana Trench, it is not of the kind or size that the megalodon would need.
As we’ve looked at what lives in the deepest part of the ocean, we’ve discovered some fascinating marine life.
Let us know in the comments which of the Mariana Trench animals is your favorite. Do you agree with us that the goblin shark is the scariest?
British-born Dan has been a scuba instructor and guide in Egypt's Red Sea since 2010.
Dan loves inspiring safe, fun, and environmentally responsible diving and particularly enjoys the opportunity to dive with sharks or investigate local shipwrecks.
When not spending time underwater, Dan can usually be found biking and hiking in Sharm's desert surroundings.