Tunas comprise fifteen species in the Thunnini family of saltwater fish. Of those, eight are considered “true tunas”: five species of bluefins and three species of yellowfins, all which belong to the genus Thunnus. (Skipjack, one of the most popular species of canned tuna, aren’t “true tunas.”)

They range in size from the four-pound, foot-long bullet tuna up to the Atlantic bluefin tuna, which weighs an average 550 pounds and measures 6.6 feet long on average. Some can grow to be much larger. 

Tunas are apex predators, which means they’re at the top of their food chain. Most eat fish, while some species prefer to feast on cephalopods like squid.

Tunas are fished extensively for food, and their speed and agility