Up until recently, it was widely believed that centipedes, creepy-crawlies with seemingly unending legs and a nasty bite, were strictly the bane of land-dwelling species. That all changed when entomologist George Beccaloni, on honeymoon in Thailand, discovered a species of giant centipede with a preference for water.

“Wherever I go in the world, I always turn over rocks beside streams, and that’s where I found this centipede, which was quite a surprise,” Beccaloni told National Geographic. “It was pretty horrific-looking: very big with long legs and a horrible dark, greenish-black color."

Instead of darting into the forest for protection, the centipede jumped into the water and, as Beccaloni recalled, swam under a rock to hide. The new species, the first of its kind known to swim, has been named Scolopendra cataracta, from the Latin for “waterfall."

Armed with a painful, venomous bite used to paralyze prey from fish to snakes, this giant species of centipede can grow to nearly 8 inches long.

Here's a picture of its mouth parts for your nightmares:

The 'tooth-plates' of the newly-discovered Scolopendra cataracta. (Photo: ZooKeys)

After capturing the specimen in a jar in 2001, Beccaloni said it swam to the bottom the jar with the power of an eel. When he later took it out of the container, the water "rolled off its body, leaving it totally dry."

But after several years in storage, the unique specimen has now been identified as similar to two unusual centipedes discovered by Beccaloni's colleague, Dr. Gregory Edgecombe, in Laos. DNA analysis confirmed that all three, as well as a specimen collected in Vietnam in 1928 (but misidentified), were part of a new species.

“Other Scolopendra hunt on land,” Beccaloni told NatGeo. “I would bet this species goes into the water at night to hunt aquatic or amphibious invertebrates.”

While these aquatic giants aren't likely interested in sampling humans, a bite from one would likely ruin the evening. Based on the horrific descriptions available online (as well as videos!), the bite is extremely painful and has been known to cause swelling, vomiting, headaches, and, we imagine, an unshakable fear of centipedes.

A thorough description of the new species, as well as other giant centipedes, has been published in the latest edition of ZooKeys.