Have you ever heard the term “horses have five hearts”? Well, that’s because the frogs (not the ones that croak and hop; the v-shaped, sponge-like tissue in the middle of the hoof) function similarly to a heart by pumping blood.
The horse was created without a muscular structure surrounding the veins in its lower leg. Because veins are not elastic, they are unable to move blood like arteries do. So how does the blood get back up the leg from the hoof to the heart? That’s where the frogs “hop” into play.
Each time the horse steps down, the frog compresses, causing the hoof to expand. When the hoof is lifted, it reduces in size. Like a sponge being squeezed, the frog expels the blood, forcing it up the leg, through the veins, and towards the heart. The frogs pump approximately a quart of blood through the body every twenty strides.
Four frogs + one heart = the phrase “horses have five hearts”
Do you know what animal actually does have five hearts? An earthworm!
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