Tuna are several species of ocean-dwelling fish in the family Scombridae. Tuna are fast swimmers and like most other fish species are cold-blooded. Unlike most ocean fish species, which have white flesh, the flesh of tuna is pink. This is because the tuna's blood has a higher oxygen carrying ability than other fish species. Some of the larger tuna species such as the bluefin tuna can raise their blood temperature above the water temperature with muscular activity. Though not really warm-blooded, this enables them to live in cooler waters and survive a wider range of circumstances. Tuna, an excellent source of lean protein, vitamins and minerals but also is low in saturated fats and cholesterol. Tuna can also help lower blood pressure and cholesterol. Research has shown that omega-3 fatty acids, found in abundance in fatty fish like tuna can help lower the risk of heart disease, ease the pain of arthritis, reduce asthma complications, and is essential in the growth and development of young children.