As tunas are often caught far from where they are processed, poor interim conservation can lead to spoilage.
In all tunas, however, the heart operates at ambient temperature, as it receives cooled blood, and coronary circulation is directly from the gills.
The heart in tunas is contained inside a fluid-filled pericardial cavity.
Tunas are, however, driven by the availability of food, not by thermal properties of water.
To overcome this, tunas constantly drink seawater to compensate for water loss.
He found a tuna's primary defense against the sharks was speed and as the fish tired they became easy targets.
In the autumn, they eat prickly pear tunas, the fruit of the prickly pear cactus.
Obligate shoalers, such as tunas, herrings and anchovy, spend all of their time shoaling or schooling, and become agitated if separated from the group.
