How Many Hearts Does A Giraffe Have?

By Antonia Čirjak on June 16 2020 in Did You Know

A giraffe only has one heart.
  • The heart of a giraffe is 2 feet long, and it weighs 24 pounds on average.
  • The blood pressure of a giraffe is 280/180 mm Hg, which is fairly high, and their hearts can beat up to 170 times per minute.
  • For every 6 inches increase in the length of a giraffe's neck, the muscles in the heart increase by another 0.2 inches.

This is a fairly easy question since a giraffe only has one heart. However, this heart is incredibly large since it needs to be able to pump blood through the extremely long neck of a giraffe. The cardiovascular system of a giraffe is actually quite fascinating, so why not explore it further?

The heart of a giraffe is 2 feet long, and it weighs about 24 pounds on average. Since these animals are so tall, it is hard to pump blood into their brain, but there are ways giraffes are able to overcome this. They use a series of valves that work in one way and force the blood to flow into the head. One other thing that helps the amount of oxygen that the giraffes can put in their blood is the size of their lungs, which is quite large as well.

Large Amounts Of Pressure

The arterial pressure near the heart of a giraffe is extremely strong, twice as strong as the one in humans. This is necessary to provide blood pressure to the brain of the giraffe. The blood pressure of a giraffe is 280/180 mm Hg, which is quite high, and their hearts can beat up to 170 times per minute.

It is obvious that not only is the heart of a giraffe large, but it is also quite powerful. Previously, humans thought that the heart of a giraffe was even bigger, but in time researchers realized that there is not enough space in their body cavities for something of that size. 

Nubian Giraffe, Giraffa camelopardalis camelopardalis, male
Nubian Giraffe, Giraffa camelopardalis camelopardalis, male.

The left ventricle of the giraffe’s heart has thick walls, so the beat of their heart is incredibly strong. The right ventricle of a giraffe’s heart pumps the blood to the lungs, and the left one pumps it straight to the head. While doing so, it needs to go against the hydrostatic pressure and the length of the artery in the neck.

The thick muscles of a giraffe’s heart have evolved through time to be able to overcome that pressure. Interestingly, the length of the giraffe’s neck and the thickness of its heart muscles are correlated. It seems that for every 6 inches increase in the length of the neck, the muscles in the heart increase by another 0.2 inches.

Overcoming The Length Of the Neck

Throughout the evolution of giraffes, their necks became longer, which in return increased the stroke volume of their hearts. The distribution of oxygen was even more difficult while the giraffes were moving, but that problem was solved through the evolution as well. Their legs got longer, which made moving easier, and the requirements to deliver oxygen were alleviated a bit.

Recently, researchers managed to discover that there is not much difference between the myocardial architectures of giraffes and other mammals. This means that there were no special adaptations to the way giraffes evolved their cardiomyocytes. They were merely able to create these large amounts of pressure because of the thickness of their myocardial wall. This is the main reason why they can push the blood through their necks. 

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