Krill oil comes from krill, which are small, shrimp like crustaceans that inhabit the cold ocean areas of the world, primarily the Antarctic and North Pacific Oceans. Despite their small size–one to five centimeters in length–krill make up the largest animal biomass on the planet. All of the krill oil supplements use the patented krill oil from Neptune Technologies called NKO. NKO contains both of the omega-3 fats eicosapentanoic acid (EPA) and docosahexanoic acid (DHA), but hooked together in a different form. In fish oil these omega-3 fatty acids are found in the triglyceride form whereas in krill oil they are hooked up in a double chain phospholipid structure. Krill oil contains vitamin E, vitamin A, vitamin D and canthaxanthin, which is, like astaxanthin, a potent anti-oxidant. The anti-oxidant potency of krill oil is known to be one of the highest among various antioxidants.