Tuna
Thunnini
Habitat: Open ocean
Diet: Carnivore
Size: Varies greatly by species
Family: Scombridae
About Tuna
Tuna are powerful, fast-swimming fish that live throughout many of the world's oceans. There are several species of tuna, ranging from relatively small fish to enormous bluefin tuna that can grow several feet long.
Their bodies are streamlined like torpedoes, allowing them to move through the water with very little resistance. This shape makes tuna especially well suited for life in the open ocean.
Built for Speed
Tuna are among the ocean's most impressive swimmers. Their muscular bodies and narrow tails are designed for fast, efficient movement through the water.
Unlike many fish that spend most of their lives in one small area, some tuna migrate across enormous distances. They may travel thousands of miles while searching for food, suitable water temperatures, and places to reproduce.
Tuna have a special ability that is unusual among fish. Some species can keep parts of their bodies warmer than the surrounding ocean water. This helps their muscles, eyes, and nervous system work effectively while they swim through colder waters.
The Sunlight Zone
Tuna spend much of their time in the Sunlight Zone, also called the Epipelagic Zone. This is the uppermost layer of the open ocean and extends from the surface to about 200 meters (656 feet) deep.
Enough sunlight reaches this zone for photosynthesis to occur. Microscopic phytoplankton use this sunlight to produce energy and form the beginning of many marine food webs.
Because food is relatively plentiful here, the Sunlight Zone contains an enormous variety of marine life. Tuna share these waters with animals such as sharks, dolphins, sea turtles, jellyfish, and many smaller schooling fish.
Tuna are capable of diving much deeper than the Sunlight Zone, however. Their exact diving behavior depends on the species, water temperature, food, and other environmental conditions.
What Do Tuna Eat?
Tuna are predators. They commonly hunt smaller fish, squid, and crustaceans. Their speed allows them to chase fast-moving prey through the open ocean.
Different tuna species eat different prey depending on their size, location, and what food is available in their environment.
Where Are They Found?
Tuna are found in oceans around the world. Different species live in tropical, temperate, and even relatively cold waters.
Rather than living on the ocean floor or remaining around coral reefs, many tuna spend much of their lives traveling through the open ocean.
Different Types of Tuna
There isn't just one kind of tuna! The tuna group includes several different species, including bluefin tuna, yellowfin tuna, albacore, bigeye tuna, and skipjack.
Bluefin tuna are among the largest. Some can reach enormous sizes, while species such as skipjack are considerably smaller.