The undersea world teems with nightmarish horror of all kinds, which we've shamefully neglected here at Infocult. To start making up for this lack, consider the Bobbit Worm.
Found in Southeast Asian waters, "[t]hese worms reach 3 m (~10 FEET) long and are raptorial predators which use spring loaded jaws to capture their prey..."
Yes, spring-loaded jaws. Five pairs of spring-loaded jaws. They look like this:
Wired offers this elevator pitch: "a mix between the Mongolian death worm, the Graboids fromTremors, the Bugs from Starship Troopers, and a rainbow — but it’s a really dangerous rainbow, like in Mario Kart ".
Using five antennae, the bobbit worm senses passing prey, snapping down on them with supremely muscled mouth parts, called a pharynx. It does this with such speed and strength that it can split a fish in two. And that, quite frankly, would be a merciful exit. If you survive initially, you get to find out what it’s like to be yanked into the worm’s burrow and into untold nightmares.
The Bobbit can take down a much larger fish, like so:
Echniblog reminds us that "[o]ne record holder indicates a worm which was nearly SIX meters in length when collected!"
And the name? Wikipedia is concise:
The name is inspired only by the scissorlike jaws of the worm; the common supposition from the name that female eunicids cut off the males' penises is baseless, and the worms in fact lack penises entirely, as they are broadcast spawners.
Much more here.
PS: comment of the year award goes to one "Smut Clyde", who observes:
The Great Google informs me that no-one is selling a "Sexy Bobbit-worm costume". Imagine my sadness.
(thanks to Charles Cameron)