The animal with the smallest heart is the fairyfly.
Fairyfly Heart Details
Fairyflies, specifically those around .006 inches long, have hearts so tiny they are only visible under a microscope. Their heart is essentially a tube running along their back. This makes it the smallest known heart in the animal kingdom.
Why So Small?
The tiny size of the fairyfly's heart is directly related to its overall minuscule size. Their simple body structure allows for a functional circulatory system with a rudimentary heart. As insects get smaller, their metabolic needs are reduced, allowing for simpler and more efficient systems.
