A blue whale’s heart has four chambers.
Like the hearts of other mammals, the blue whale’s heart has two atria and two ventricles. The right side receives oxygen-poor blood and sends it to the lungs, while the left side pumps oxygen-rich blood around the body. This four-chambered arrangement keeps oxygenated and deoxygenated blood largely separate.
The blue whale’s heart is famous for its enormous size, but popular descriptions sometimes exaggerate its weight or compare it with a small car. Estimates vary because weighing a complete heart is difficult, especially in a stranded animal. Its size reflects the whale’s immense body and the demands of swimming and diving, not a different basic heart design.
Blue whales are mammals, so they share this four-chambered heart plan with humans, seals and other whales. Their unusual adaptations instead include powerful lungs, high blood volume and muscles rich in myoglobin, which help them remain underwater while feeding or migrating.