30 Weird Sea Animals You'll Never Forget
Experts say that we have only mapped out and discovered about 20 percent of the ocean. Even in the small amounts that we have discovered and explored, there are constantly mysteries and mysteriously strange species that we find. It can be hard to believe that these sea animals share the same planet as us humans. They can be strange-looking, weirdly shaped and often difficult to find.
Of the sea species we have uncovered, there are a handful of particularly odd animals that will either fuel your imagination or maybe haunt your nightmares. Here are some of the weirdest animals in the ocean, ranked based on how strange, bizarre and terrifying they are.
Physical traits: A smooth-looking outside with an uncanny ability to blow themselves up into a bigger and rounder version of themselves with tough spikes around their body.
Length: Average around 3 feet
Weight: About 6 pounds
What Makes the Porcupinefish So Weird
These fish are also often called “blowfish,” and their abilities to become large and intimidating quickly will blow you out of the water. These fish swim around looking like your normal, run-of-the-mill fish until threatened, then suddenly become unrecognizably huge and genuinely dangerous.
And, interestingly enough, the males woo females by creating complicated geometric patterns out of the sand for their nests. So, they’re both fierce and fiercely artistic.
Physical traits: Colorful fish with higher-than-average intelligence and generally territorial (and cranky) attitudes with very distinct teeth protruding from their mouths.
Length: 28 inches
Weight: Up to 13 pounds
What Makes the Triggerfish So Weird
Even though this fish’s bizarre-looking teeth are used to help them crush shells, they won’t hesitate to use them on humans. Notoriously protective of the nests and fearless in their pursuit of whatever made them cranky that day, Triggerfish aren’t afraid to go after a human if they feel threatened.
And though most species are too small to do damage, Titan Triggerfish are big enough that they could actually hurt you if you happen upon their nest.
28. Thornback Cowfish
Physical traits: Beautiful and goofy-looking at the same time, these fish have both distinctly bright markings and a sucking snout and protruding eyes fused onto their hexagonal face.
Length: Around 6 inches, typically 9 inches maximum
Weight: Usually only a few ounces
What Makes the Thornback Cowfish So Weird
Despite their appealing appearances, these fish are a poisonous type of boxfish typically found in the tropics. This particular species of boxfish is rare and can be distinguished by their anteater-like snout along with their funky triangular eyes.
They are typically yellow with brightly colored markings in deeper colors like purple or blue. They feed on invertebrates off the seafloor and, thanks to their eye and mouth placement, always look sad while doing so.
27. Peacock Mantis Shrimp
Physical traits: Large shrimp creatures that look like they’ve been painted by a full-on rainbow, complete with bright purple-ish eyes.
Length: 1-7 inches
Weight: 0.4-3 ounces (12 - 90 grams)
What Makes the Peacock Mantis Shrimp So Weird
This particularly colorful mantis shrimp has a number of names including harlequin, painted, clown or rainbow mantis shrimp. They’re rather large and tend to be in charge. Even if their appearance gives off the hippie relaxed vibe, these fish are strong enough that they’ve been known to do damage on aquarium glass by tapping on it.
They have long appendages typically curled up into their body that unfurl quickly (50 times faster than the blink of an eye!).
26. Frilled Shark
Physical traits: Long, eel-like brown body with gill slits at the throat and a large mouth filled with needle-like teeth
Length: As large as 6.6 feet
Weight: Around 1.3 pounds
What Makes the Frilled Shark So Weird
Considered a living fossil, this slithering shark has a body that resembles a snake or an eel more than an average shark. It has large gills on the side of its face that give it an extra intimidating dragon-like appearance as it stares directly at you. And its teeth aren’t your normal, large shark teeth. They’re small and needle-like, with tons of them in every spot where one tooth normally is.
And to make matters worse, they’re everywhere but don’t like to be seen. So you never know when one is watching you. Fortunately, (or unfortunately, depending on how you look at it) sharks are far from the most dangerous animals in the ocean.
25. Atlantic Wolffish
Physical traits: Brown or gray catfish-looking fish with protruding and sharp canine teeth.
Length: Up to 5 feet
Weight: Up to 50 pounds
What Makes the Atlantic Wolffish So Weird
These fish look like they’re always having a bad day. And thanks to their powerful canines and impressive bite power, they aren’t afraid to make you have one as well. They have protruding noses over their large-lipped bodies, which makes them look a little too human-like for comfort.
Though they may not be able to howl like the canine wolf species they were named after, they certainly would make you squirm if you were swimming nearby one.
24. Arctic Hydromedusa
Physical traits: A bioluminescent jellyfish creature whose insides glow.
Length: Less than 1 centimeter
What Makes the Arctic Hydromedusa So Weird
These small but fascinating creatures don’t leave much to the imagination when it comes to their innards. Like many of their hydrozoa family, they glow from the inside.
They move around by contracting their bell-like bodies and using their floating tentacles to sting their prey. Though they may only eat plankton, their Medusa-like look is still unnerving to the average swimmer. And because of that, if you see one, you probably shouldn’t stare straight at it.
Physical traits: Colorful bodies and fused teeth that look like a beak.
Length: Average around 4 feet
Weight: Around 45 pounds
What Makes the Parrotfish So Weird
This large family of fish all have fused teeth that help them to scrape coral from coral reefs. But it also makes them look like they have a bird beak.
And combined with their colorful appearance, a person might expect to hear these fish start repeating words like a parrot might.
22. Clown Frogfish
Physical traits: Variable but often brightly colored with small prickly looking spots all over its angled and strangely shaped body.
Length: Up to 6 inches long
Weight: Not recorded
What Makes the Clown Frogfish So Weird
Sometimes also called the warty frogfish, this fish looks like it was covered in warts and accidentally rolled itself against some drying paint. At first glance, it’s hard to distinguish its fins from its face.
These fish can change colors to camouflage, which is impressive considering how unique they already look.
21. Japanese Spider Crab
Physical traits: Orange body, crab-like features and extremely long legs.
Length: As large as 12 feet
Weight: Around 44 pounds
What Makes the Japanese Spider Crab So Weird
When you see a Japanese Spider Crab, you understand why people have nightmares about them. These large crabs have incredibly long legs that are the biggest of their kind (at least based on what humans have discovered so far).
Even though they’re not outright aggressive towards humans, they’ve been known to do damage with those powerful claws. Plus, they’re excellent at camouflage, so it’s possible you could be swimming right on top of one without even knowing it. Enjoy your future ocean dives!
20. Christmas Tree Worm
Physical traits: Colorful worms that live on coral and are shaped like Christmas trees.
Length: Around 1.5 inches
Weight: A few ounces maximum
What Makes the Christmas Tree Worm So Weird
It looks like Santa Claus may even find time to travel under the sea, thanks to these beautiful evergreen-shaped worm structures. These worm appendages are not only brightly colored, their triangular shape allows them to better move and trap prey. And they don’t just have one tree per worm.
They each have two structures on their bodies called crowns. They’re so festive-looking that it’s surprising Hallmark doesn’t already have a few movies dedicated to them.
19. Bioluminescent Octopus
Physical traits: Octopus that can glow in the dark from its suckers.
Length: Largest measured around 17 feet
What Makes the Bioluminescent Octopus So Weird
Also called the glowing sucker octopus, this glow-in-the-dark species has all the strangeness (and intelligence) of an octopus with an added layer of bioluminescence.
What makes them even more fascinating is the fact that they don’t just always glow. They need proper stimulation. And even then, sometimes they glow continuously, and sometimes they choose to glow in circular patterns, making them look like they are sparkling.
18. Flamingo Tongue Snail
Physical traits: Small coral reef snail with bright pink or orange markings and black spots.
Length: About 1 inch
What Makes the Flamingo Tongue Snail So Weird
These brightly colored snails actually get their coloration and name from their soft tissue, which wraps around their shell. Their colors are meant to ward off predators as a warning that they’re toxic since they’ll often store toxicity from corals they are eating in their own bodies.
They can retract to go back inside their shell, but usually only do so if attacked. They also look similar to the highly venomous Cone Snail in terms of their markings, so best to leave them alone just in case. Typically, they hang out on coral they’re preying on, slowly and patiently eating away at it — and looking fabulous while doing so.
Physical traits: Usually dark or silvery blue with long, thin bodies and oversized fangs in its wide mouth.
Length: 11-12 inches
Weight: Typically .45 ounces
What Makes the Viperfish So Weird
If you were to design a horror-themed funhouse with a large, unwelcoming, fang-filled mouth that people had to walk through to get inside, you would likely use the Viperfish’s naturally terrifying shape. And their hinged jaw allows them to have incredibly long (we’re talking between 12 and 23 inches) needle-like teeth.
Because they typically live in very deep waters and don’t often interact with humans, it’s unclear just how dangerous they are. But based on their look alone, if you do encounter one, it’s best to leave them be.
16. Tasselled Wobbegong
Physical traits: A flat body and head covered in distinct markings and fringe branches around its head and chin.
Length: About 6 feet
What Makes the Tasselled Wobbegong So Weird
This shark looks like a living room rug come to life. And that rug now has teeth. And that rug will use those teeth to bite you if you come too close to it. Because the rug is actually a shark.
These flat sharks are not just hard to spot because of their thin bodies, but their distinct color patterns and fringey scales make them particularly difficult to see. Though they’ll leave you alone if you leave them alone, unlike some other species of shark, don’t tempt or tease them because they will bite back. They don’t like to be walked all over (like a … rug).
15. Sea Pen
Physical traits: A floating multicolored animal that looks like an old timey quill.
Length: About 1.5 pounds
Weight: About 4 ounces
What Makes the Sea Pen So Weird
If you didn’t think you could write effectively underwater, this animal makes you think again. Named after the fact that it looks just like an antique quill pen, there are a number of different variations of the sea pen. They float along the ocean floor with feather-like fins coming off the sides.
With all the things you’d expect to find on the ocean floor, a pen waiting for Shakespeare to come along and use it certainly isn’t one that comes to mind.
Physical traits: Typically pink animals that look like extra large and less wrinkly worms that have a sucking mouth on one side.
Length: 19-25 inches
Weight: 6-9 ounces
What Makes the Hagfish So Weird
Take the creepy mouth from the “Stranger Things” monster and put it into a large, snake-like creature that hovers along the ocean floor, and you get a Hagfish. It’s like someone took a bunch of creepy elements, including a thick eel body, the slithering of a snake and an intimidating, open gill mouth and put them all together in this animal.
One look at its ugly features, and you’ll wonder why it wasn’t named the “Gagfish.”
13. Goblin Shark
Physical traits: Pink sharks with an extra-long snout and large jaws, complete with intimidatingly sharp shark teeth.
Length: Up to 12 feet
Weight: Up to 460 pounds
What Makes the Goblin Shark So Weird
The appearance of this animal alone is enough to give you the creeps. It’s part of a family that's over 125 million years old and is considered a living fossil. It looks like what might happen if you combine all the intimidating elements of a more common shark, then add in an extendable jaw and a bayonet-like snout.
Luckily for us easily startled humans, these unnerving giants are relatively solitary and especially rare to see.
12. Yeti Crab
Physical traits: Yellowish-white crab with long legs and what look like large hairs coming off its legs.
Length: Around 6 inches
Weight: 2-5 pounds
What Makes the Yeti Crab So Weird
You don’t typically associate sea creatures with being hairy. And the fact that this creature was first discovered recently, in 2005, means it was able to stay hidden and mysterious, like the Yeti, for years.
The hairs on its arms aren’t just for looks, though. Scientists believe that they are actually small bacteria farms that the crab grows to feed itself. Cool?!
11. Vampire Squid
Physical traits: Either deep black or light red or somewhere in between, these (literal) suckers look like a mix between a squid and an octopus with distinct bioluminescent abilities.
Length: Around 1 foot
Weight: Around 1 pound
What Makes the Vampire Squid So Weird
Even though they have an intimidating name and particularly strange features, like small ear flaps on either side of their umbrella-looking body, these creatures prefer sucking on plankton to sucking down human blood. They exist in extremely deep-sea conditions, preferring to be lightless in what’s considered a “shadow zone,” where oxygen is rare and few creatures survive.
Yet somehow, these animals do just fine, which may be proof they really are from an unknown underworld.
10. Sarcastic Fringehead
Physical traits: Typically small, brown fish with extra-large jaws and fringe around their eyes.
Length: Typically around 3-8 inches, but can get as big as 1 foot
Weight: Not recorded
What Makes the Sarcastic Fringehead So Weird
Don’t let their size fool you, these territorial large-mouthed fish aren’t afraid to come after you if you get too close to their nest. Or they’ll battle each other for dominance, which looks like they’re kissing since the mouth and body size are what establish dominance.
They move quickly around like little darts ,and you don’t typically see them coming since they like to live and hide in crevices.
9. Barreleye Fish
Physical traits: Oh, you know, normal fish stuff except for their barrel-shaped eyes and, oh yeah, they’re iridescent, glowing visible eyeballs.
Length: Around 6 inches
Weight: 2-5 ounces
What Makes the Barreleye Fish So Weird
They say the eyes are the windows to the soul. But in the case of the Barreleye Fish, you can see deep into the soul of this creature thanks to its distinct, transparent head.
Their eyes have green caps on them that are visible through the head. And they’re able to see not only forwards but upwards thanks to, well, the good visibility.
Physical traits: Vibrantly colored mollusks with distinct and striking shapes.
Length: Between .5-12 inches
Weight: Up to 3.3 pounds
What Makes the Nudibranch So Weird
If you think your family reunions are colorful, try a Nudibranch reunion. This branch of mollusks have a ton of different shapes, sizes and colors that all fall under the same genus.
They are shaped like small art sculptures, complete with bilateral symmetry and all. And they typically have colorful tentacles that help them survive.
7. Marrus Orthocanna
Physical traits: A glowing wand-looking creature with several polyps on each side.
Length: Can be several feet long
Weight: Not recorded
What Makes the Marrus Orthocanna So Weird
Any fans of “Star Trek” may be familiar with The Borg, a colony that all work together on one ship. This creature is the same idea — a group of zooids all floating around the ocean surviving together.
These are typically found deep in freezing waters and legitimately look like a glowing rocketship with a bunch of tiny boosters built onto the sides.
6. Black Swallower
Physical traits: A darkly colored, scaleless fish with a jaw that can swallow something 10 times its size.
Length: Usually around 4 inches but can get as big as 9 inches
Weight: Depends on what’s in its belly
What Makes the Black Swallower So Weird
Sometimes after a big meal, we humans may have to unbuckle one of our belt buckles. Well, not this fish. The Black Swallower was made to swallow fish much larger than itself and has a built in system to not only digest them, but to also swim along proudly carrying the giant fish in its belly.
They’ve never been caught on camera, so they’re difficult to find. But, sometimes, when one has something that begins to decompose in its belly before it can digest it fully, it can cause a gas that brings it from the deep sea into shallower waters. You’ll most likely only ever see one that is full whose farts are making it float upward, much like the iconic scene in “Willy Wonka & the Chocolate Factory.”
5. Red-Lipped Batfish
Physical traits: A lightly colored fish with spots and wing-like protrusions that looks like it put on too much lipstick before heading out on the town.
Length: Around 10 inches, but can get as big as 15 inches
Weight: Not recorded
What Makes the Red-Lipped Batfish So Weird
This fish looks like it’s perpetually biting into a set of those red wax lips you can buy at drugstores. And if that weren’t odd enough, it has a five o’clock shadow around its lips and face, plus extra hairs on its nose. And to top it off, it has a set of protruding eyes that look like they’re perpetually disappointed at whatever they see.
And even though it's dressed to be looked at, it’s an awkward swimmer that is usually found scurrying around the ocean floor. Basically, it’s all of us after too many drinks at a club.
4. Faceless Cusk
Physical traits: Large nose on an eel-like body with a hard-to-see mouth under the body and no visible eyes.
Length: Around 18.3 inches
Weight: Not recorded
What Makes the Faceless Cusk So Weird
This fish was first described in a famous 1870s expedition but then rediscovered in 2016. Its head is bulbous with a visible nose and a hidden underside mouth. But the strangest part of this fish is the fact that you basically can’t see any eyes. It’s like staring at a faceless creature (hence the name).
Upon further inspection, there are technically eyes present, but they’re very small and hidden under layers of gill. And because you can’t look into its eyes, it’s hard to tell what this creature is thinking. So best to keep away.
Physical traits: Slimy, large mass with curved nose, big eyes and a perpetual frown.
Length: Up to 27 inches
Weight: Up to 21 pounds
What Makes the Blobfish So Weird
Arguably the most memeable animal on this list, these fish answer the question: “What happens if you melted a sad human face onto a chunky fish body?”
They don’t have a lot of muscle and mostly just float around waiting for prey to get close enough to eat. They’re considered the ugliest fish in the world, which might explain why they always look so down.
Physical traits: Darkly colored with a massive jaw.
Length: Around 7 inches
Weight: Not recorded
What Makes the Fangtooth So Weird
These fish swim around deep, dark waters with their extra-large and extra-long jaws filled with extra-sharp teeth preying on more symmetrical (and smaller) fish. Some species just eat plankton but still retain their intimidatingly large mouth and jaw structures.
Because their mouths are so large, they don’t even have to be that accurate when they go out hunting for food. They can get close enough and let their mouths do the rest of the work.
Physical traits: Most distinctive trait is a little dangling bit of spine that looks like a limp unicorn horn between the eyes.
Length: Between 8 inches and 3 feet
Weight: Up to 100 pounds
What Makes the Anglerfish So Weird
Anglerfish look like something a more sinister Tim Burton would create. Though there are many types of Anglerfish with competing disconcerting features, what makes this type of fish the absolute weirdest animal in the ocean is the fact that they basically use a small fishing pole in front of their face in order to lure their prey.
So not only are they full of odd-looking features, but they’re basically fishermen. Only they’re fish. So they’re fisherfish.