Plasmic fiber

Plasmic fibers were anatomical features of the Tosk species. These fibers enabled the Tosk to store liquid nutrients throughout their bodies, greatly reducing their need to take in sustenance. They had this ability due to being genetically-engineered by their creators, the Hunters.

In 2369, Tosk declined Miles O'Brien's offer of food, explaining this feature of his anatomy.(DS9: "Captive Pursuit")