Circulatory System
Birds have a four-chambered heart, in common with humans, most mammals, and some reptiles (namely the crocodilia). This adaptation allows for an efficient nutrient and oxygen transport throughout the body, providing birds with energy to fly and maintain high levels of activity. A Ruby-throated Hummingbird's heart beats up to 1200 times per minute (about 20 beats per second).
Read more about this topic: Bird Topography
Famous quotes containing the word system:
“Exploitation and oppression is not a matter of race. It is the system, the apparatus of world-wide brigandage called imperialism, which made the Powers behave the way they did. I have no illusions on this score, nor do I believe that any Asian nation or African nation, in the same state of dominance, and with the same system of colonial profit-amassing and plunder, would have behaved otherwise.”
—Han Suyin (b. 1917)