Carnictis sordicus (vile meat-weasel)

Carnictis Sordicus from the movie

King Kong (2006)

Carnictis sordicus (vile meat-weasel) is a huge wormlike creature that lives in the abyssal chasms of Skull Island. They can be 7-13 feet long.

"Writhing, serpentine, vermicular predators of the tepid sludge that suffocated the depths of the chasms, they are feeders on the dead and wounded. Carnictises are slow-moving but relentless. Lacking eyes or a face of any sort, they are little more than an animated stomach that folds in and out of itself with obscene undulation.

 

Intestinal parasites similar to the tapeworms that can infest humans, the ancestors of Carnictis lived in the guts of large predatory dinosaurs, where they devoured the half-digested flesh swallowed by their hosts. At some point in their history, these gut parasites must have evolved so that they could survive outside the confines of their hosts' intestinal tracts. They made their new homes in the geothermal spring-fed sludge that clotted the bowls of the island. It is theorized that long ago, a V. rex-like predator fell into one of the chasms and died, its parasite cargo disgorging slowly from the carcass to find themselves in the rich organic river in the pit's base. Instead of drying up and dying, they thrived. Warmed by the hot, geothermal water bubbling into the syrup of the pits, the worms were sustained on the flesh of animals falling into the chasm from the jungle above. Parasites no longer, they swelled to disturbing new proportions and became carrion eaters in the abyss. With their new size and strength, they could overwhelm and consume live prey, dragging the slow or wounded to their deaths below the surface.

Requiring very specific environmental conditions, Carnictises are restricted to a few cavernous rents and sinkholes that suited their particular needs. Squirming downstream through the muck to where the chasms open into rivers is death. The cooling water sucks their lives away, while any pit that saw a drought of carrion or fresh meat would similarly devastate the Meat-weasel.

However, Carnictis developed a survival strategy. While the adults are susceptible to change, eggs can survive for decades in a dormant state, waiting for a return of favourable conditions to hatch and spread."  (source)