How can a Hummingbird’s heart be larger than a Blue Whale’s?

By eNature

Think those heart-shaped boxes of Valentine’s chocolates are impressive? Compared to the size of a human heart perhaps. But a whale’s heart dwarfs even those samplers that require weightlifters to hoist them.

Picture a heart the size of a car. That’s what a Blue Whale possesses – a heart that deserves its own parking space.

And how does a heart like that pump? Very slowly. In fact, a Blue Whale’s heart beats just five or six times per minute when the whale is at the surface and even slower when the animal dives. A human heart, by contrast, typically beats seventy times per minute at rest. And a hummingbird’s heart, for even greater contrast, beats five hundred times per minute at rest and more than a thousand times per minute when the bird flies.

But don’t underestimate the little hummingbird. Its heart is the largest proportionally of any animal. Whereas the average mammal’s heart comprises less than 1 percent of its total body weight, a hummingbird’s heart can be more than twice that figure. For a Blue Whale, that’s the equivalent of a two-car garage.

Click here to learn more about the Blue Whale »

Click here to learn more about the Ruby-throated hummingbird »