5 Underwater Creatures That Look Like Terrifying Nightmares

But if that's not quite alien enough for you, turn out the lights and let the party begin:

Yeah, now that shit looks less like an alien and more like the goddamned UFO it arrived in. It's popularly called the alarm jellyfish, and to appreciate it, you really need to see its pulsing light show in action (note: We are 100 percent sure they did not add the porn soundtrack to this clip -- that's just this creature's mating call):

Yeah, the Atolla jellyfish is basically a Pink Floyd concert with more tentacles and fewer floating pigs, and it's oftentimes the only thing visible in the abyss surrounding it. And that's just the way it likes it: The Atolla jellyfish doesn't use its built-in lava lamp to hunt, but rather as a scream for help. If the jellyfish senses that something is interested in tasting the rainbow, it suddenly lights up like a rave, something that scientists call its burglar alarm response. The point is to either scare the attacker away or attract something even bigger so the diner suddenly becomes the buffet.

The tactic is so effective, in fact, that we humans are stealing it for ourselves. Since dropping lit-up games of Simon into the water wasn't achieving results, biologist Edith Widder constructed an electronic Atolla jellyfish replicant that can attract rare undersea fauna for observation and study.

Holy fucking shit. We've just gone from "looks like a psychedelic alien" to "looks like a boss character from a survival horror video game."

That there would be the skeleton shrimp, a demonic overlord that has entered our dimension to seek vengeance for all of its brethren you've thrown on the barbie and slathered in breadcrumbs.

Actually, skeleton shrimp aren't even shrimp at all, but rather amphipods. And you need a magnifying glass to reveal their horror, since they're only a few millimeters long at best. So if Disney wants to cast their creepy asses as the villains in Finding Nemo 2, they'll have to scale them up a bit (and then watch the parent complaints come rolling in).

Not that their size makes us feel that much better about them; it just means that if you go swimming, you could have this little guy floating into your ear canal and not even know it:

And of course they have giant claws (proportional to their bodies, anyway), because no spiritual harbinger of terror and despair is complete without them. Those nasty-looking things (called gnathopods) excrete poison and are perfect for both murder and holding down males during mating sessions. But girl skeletons have poisonous claws too, so if the male doesn't deliver like he should, she will poison-stab him to death.

If you're not familiar with how deep-sea evolution works, basically it's like this: All of the greatest fears and darkest nightmares of humanity rise up to the atmosphere, where they are eventually carried over the oceans and rained down, causing our collective terror to descend into the cold darkness and, over time, congeal into writhing horrors like you see above.

In order to cope with the knowledge that we share the planet with such monsters, we humans give these creatures exceptionally ridiculous names. This one we call the stoplight loosejaw, which sounds like the worst SpongeBob spinoff imaginable.

"Stoplight" refers to how the fish glows red. This is especially helpful, because most deep-sea desserts (the loosejaw's preferred term for its neighbors) can't detect any colors outside of blue. By illuminating red instead, the loosejaw can essentially hunt with an invisible flashlight.

Then there's the "loosejaw" part. The stoplight can almost completely separate its lower jaw from its head and stretch its head so far past its body that it damn near decapitates itself. This creates a Mortal Kombat-esque spike pit that can quickly impale any passing prey, as well as cause any freaked-out witnesses to wonder when the babies will start popping out of its neck.

Also, in order to reduce water resistance (and for added general creepiness), there's no floor to the stoplight's lower jaw. This allows it to droop its goofy-yet-charmingly-awful bear-trap jaw to ludicrously low levels and keep its head dangling by a membrane, like an execution performed by a dull, rusty ax. To its prey, it no doubt appears to have been brutally murdered ... right up until it eats them.

This is the glorious flatworm, a gaudy invertebrate native to the tropical Indo-Pacific that has surely made more than one concerned diver check his tank mixtures to ensure that nobody laced his oxygen with LSD. Just watch this ridiculous, hypnotic thing in action:

Its spellbinding undulation, allowing it to effortlessly glide through the water like an anthropomorphized afghan, is accomplished thanks to countless hairs along its length that act as tiny paddles. In addition, its bright colors alert all but the stupidest would-be predators that it's poisonous and not to be eaten. This isn't actually the case (they're as harmless as can be), but still, we've never seen a creature that looked less like food. Or less like a creature. Seriously, this should not exist as a living thing:

It's mesmerizing. Stare at it too long and you soon won't want to do anything else. Just watch it dancing endlessly through the water until you want to go join it, under the sea. Forever.

Why, you could almost think they're beautiful ... until you watch one eat. They engulf their prey whole like a zombified gypsy shawl, then a tubelike appendage grinds the unfortunate victim into a pulpy, chewy goop. As for its after-dinner poop, it just pukes up anything it can't digest, since it doesn't have an anus and all.

And on the eighth day, God said, "Time to throw all my useless trash in the blender and see what happens."

The result is a scorpionfish, because hey, there's probably a scorpion in there somewhere, right? Granted, most types of scorpionfish are polite enough to at least look like fish. This is not the case, however, with the random assortment of nonsensical bric-a-brac called the Ambon scorpionfish.

You would be forgiven for thinking that's just some neglected sapling and not a poisonous, carnivorous terror of the deep. But it totally is -- what looks like dead leaves are actually its fins, and what looks like thick branches are actually ... antlers? Shit, we don't know. And if we can't figure it out, what hope do the poor other fish have? Based on this, not a whole lot:

Yep, just because Nature slapped Wilford Brimley's eyebrows onto a pile of cocktail umbrellas doesn't mean the Ambon still can't straight-up suck down a sizable fish like a goddamn spaghetti noodle. And since they're covered in poisonous spines (ah, that's why they're called scorpionfish), they could kill you, too. So try not to step on one, if you can even fucking identify what it is.

The scorpionfish family isn't content with just one surreal-looking family member, though. Meet the weedy scorpionfish, a variant that's gaining popularity in the aquarium circuit, presumably among supervillains who mistake it for the long-lost purple kryptonite that will kill Superman for good this time.

Like its Ambon-y cousin, the weedy scorpionfish doesn't look at all like the species it identifies itself as on its tax form. A lot of times, it's even hard to tell which end of the fish contains the face.

And like its cousin, it too is covered in poisonous barbs and can kill you simply by hanging underfoot. So, happy swimming, we guess.

Many thanks to Carly Brooke of The Featured Creature for her invaluable help in researching this article. E. Reid Ross is a columnist at Man Cave Daily and has a Twitter here.

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Related Reading: You can find crazier stuff underwater, like this gigantic Sarlacc. If you're in the mood for some real body horror check out this fish that looks like the Predator. If you're not still horrified enough, read our list of terrifying prehistoric creatures that are still around.