By looking at a Hydrotian, or Trencher as the military referred to them, it was hard to believe they were ever human at all. Other than having a head, two arms and two legs, the similarities to humans ended there. Within minutes of swallowing the poisonous ocean water, a thin chrysalis formed around the body, protecting the Hydrotians during the mutation process. The mutating Hydrotians soon developed fish-like gills in addition to their existing human lungs. Six gill slits formed beneath each armpit and allowed the creatures to begin breathing water. The new gill-lung mutation was fascinating, as it allowed the Hydrotians to breathe both water and air.
Facial features also became much more gruesome in appearance. Since the gills fed air into the lungs, a human nose was no longer needed for breathing. The face flattened, leaving a small bump of cartilage where the nose had been.
The mouth became much larger and shark-like, with multiple rows of teeth. And, like a shark, when a tooth was lost it was replaced by a sharp new tooth.
The Hydrotians developed freakishly large eyes that could gather faint rays of light, streaming into the ocean depths from above. The eyes allowed the Hydrotians to see very clearly along the dark ocean floor.
Hydrotian skin was well suited for ocean life and even changed color to camouflage the body depending upon the current environment. Along the seafloor the skin darkened to a shimmering, bluish-green color. The skin gradually lightened as the Hydrotians moved toward the surface. As protection from the cold water, the skin developed a protective outer layer, which had a disgusting, slimy fish-like texture.
Although Hydrotians went through many physical changes they remained as intelligent as they were before the mutation. They used their human-like abilities to develop new weapons and build their civilization along the floor of the deepest sea trenches and caves. The deep-water trenches were ideal locations to build, as it was difficult for the human military to find them.
As far as mankind was concerned, the most frightening part of the mutation was the chemical change that occurred in the Hydrotians’ brains. The Hydrotians had a primitive, war-like mentality and a deep hatred for humans. It was quite clear that the Hydrotians intended to destroy mankind. Unfortunately, peace was not an option.