A turkey possesses a single heart, much like all other birds and mammals. While it has only one heart, the organ is a highly specialized piece of biological machinery that supports the bird’s active metabolism. This single heart and its associated circulatory system are adapted to the unique demands of avian life.
The Turkey’s Circulatory System
The turkey’s circulatory system is a closed system, meaning blood is constantly contained within vessels. At the center is a single, four-chambered heart, structurally similar to the human heart. It consists of two upper receiving chambers (atria) and two lower pumping chambers (ventricles). This four-chambered design ensures a complete separation between oxygenated and deoxygenated blood.
The right side of the heart manages deoxygenated blood, pumping it to the lungs for gas exchange. The left side receives the newly oxygenated blood, and the left ventricle forcefully pumps this oxygen-rich blood out to the body’s tissues. This efficient separation allows for the highest concentration of oxygen to be delivered to the muscles and organs, which is necessary for a large, active bird.
Distinctive Features of the Avian Heart
The turkey heart is larger in proportion to its total body mass compared to a mammalian heart of similar size. This size is a direct adaptation to the high metabolic rate required by birds, even those that rarely fly. The heart achieves a large stroke volume through stronger, thicker muscular walls, particularly in the left ventricle, which generates the high pressure needed to circulate blood.
The left ventricle wall is often two to three times thicker than the right, reflecting the difference in workload between systemic circulation and the lungs. Birds maintain a faster resting heart rate than mammals of comparable mass, with rates ranging from 192 to 396 beats per minute. The internal structure of the avian heart valves is also distinct; the right atrioventricular valve is a muscular flap rather than the fibrous tricuspid valve found in mammals.
Other Unique Turkey Anatomy Facts
The Snood
The fleshy, often brightly colored appendage hanging over the beak is called the snood. This structure can engorge with blood, changing in length and color to signal health and dominance. The snood is an important ornament used in mate selection.
Vision
Turkeys have specialized vision that is superior to human sight. They have a nearly 360-degree field of view because their eyes are positioned on the sides of their heads. This wide visual range and excellent color perception allow them to detect movement from significant distances, serving as a primary defense mechanism.
The Gizzard
Like many other birds, turkeys do not have teeth and rely on a specialized muscular stomach called the gizzard to grind their food. They ingest small stones or grit that are held within the gizzard to mechanically break down tough plant material and seeds.