What anatomical feature differentiates the frog heart from the human heart?

The anatomical feature that differentiates the frog heart from the human heart is the presence of a single, fused ventricle. In amphibians like frogs, the heart has three chambers: two atria and one ventricle that is not completely divided. This fused ventricle allows for both oxygenated and deoxygenated blood to mix to some extent, which contrasts with the human heart, which has four distinct chambers: two atria and two ventricles. This separation in humans facilitates more efficient circulation, ensuring that fully oxygenated blood is delivered to the body while deoxygenated blood returns to the lungs for oxygenation.

Frogs do possess two separate atria, which allow them to collect blood separately from the body and lungs, but the key differentiator is the single, fused ventricle that characterizes their circulatory system. The presence of a septum, which is a dividing wall between heart chambers, is not found in frogs as it is in humans, further defining the structural differences between these two species' hearts.