Pacific bluefin tuna

Bluefin tuna are some of the largest and fastest fish in the ocean—they’re powerful swimmers, built for endurance and speed. To help conserve energy on their long-distance journeys, tuna’s bodies are almost perfectly streamlined, reducing drag around their fins. And tuna can retract or fold those fins against the body so water flows more smoothly over their bodies. This makes them super-streamlined.

Unlike most fish, tuna are warm-blooded and can heat their bodies to 6° C (11° F) warmer than the surrounding water. This added warmth helps their muscles work faster and more efficiently. Tuna consume as much as 5% of their body weight daily and must continually swim with their mouths open to force water over their gills, supercharging their blood-rich muscles with oxygen.

Pacific bluefin tuna spawn off of Okinawa; between Taiwan and the Philippines; and in the Sea of Japan. They migrate over 6,000 nautical miles (11,112 km) to the eastern Pacific, eventually returning to their birth waters to spawn.