The Tosk are a Gamma Quadrant species whose existence is to be hunted. The live to outwit and elude the Hunters. They hope to die with honor then by captured and then be humiliated and abused.
All Tosk train themselves for the hunt. They only require 17 minutes of sleep per rotation. Each rotation is nearly one Earth day. Liquid nutrients are stored in plasmic fibers located throughout their bodies.
The Tosk are intelligent beings. Their sentience not only makes them aware of what they are supposed to do, but it allows them to access the situation and take appropriate actions. They can operate ships and repair them. They can decipher various codes and security systems.
They are wary and don't trust anyone. They are sworn to an oath of silence. This makes sure that they only survive using their wits.
The Hunters have various technologies to hunt the Tosk. The Hunters are pompous and are cruel to their pray. They don't consider the hunt to be cruel.
The Hunters were red uniforms with silver helmets. Their helmets have special tracking sensors. Built-in metallic shield generators can withstand a Starfleet phaser set on setting six. They are physically strong.