The tuna is known as oceanic fish of the family Scombridae, mainly of the genus Thunnus. Tuna is a fish rich in phosphorus, selenium, potassium and Ω3 polyunsaturated fatty acids. Its low content of saturated fatty acids and cholesterol make it an ideal dietary proposition for low fat diets. Phosphorus is a bone structural material, but it also has several metabolic effects, forming a component of certain lipids that are involved in the formation of cell membranes. Selenium, contained in the tuna in synergy with vitamin E, protects organisms sensitive to oxidation. Finally, the potassium, contained in tuna in a significant amount, contributes to the transfer of nerve impulses, the control of muscle contractility and the maintenance of blood pressure.
The tunas have hydrodynamic and compact body and can reach high speeds up to 70 km / h. The tuna meat is usually red, yet other tuna fish have white meat. In red tunas, their hue is due to the presence of myoglobin in the muscles of the fish. Myoglobin is an oxygen-binding protein and tunas overexpress it. Some of the largest types of tuna have warm-blooded organisms, as they can increase their body temperature to a greater value than the surrounding water, and thus can live in cold seas.