The Secret to the Giraffe's Long Neck: Uncovered

The giraffe's long neck has been a long-standing mystery, often attributed to its ability to reach succulent leaves on tall acacia trees in Africa. However, a new study reveals that the giraffe's long legs actually play a crucial role in reducing the energy cost of pumping blood to its brain, allowing it to survive droughts and breed throughout the year. The study, which compared the energy cost of a typical adult giraffe to an imaginary creature with short legs and a longer neck, found that the giraffe's legs "save" a net 5% of the energy it takes in from food. This energy saving would add up to over 1.5 tonnes of food per year, making a significant difference in survival on the African savannah.

Key Takeaways:

• The giraffe's long neck comes at a high cost, with its heart needing to produce enough pressure to pump blood a couple of meters up to its head, resulting in a blood pressure of over 200mm Hg.
• The energy cost of the heart increases in direct proportion to the height of the neck, making the giraffe's heart work harder than necessary.
• The giraffe's long legs, however, contribute to the reduction of energy cost, saving a net 5% of energy compared to an imaginary creature with short legs and a longer neck.
• The energy saving would add up to over 1.5 tonnes of food per year, making a significant difference in survival on the African savannah.
• Giraffes are forced to splay their forelegs while drinking, making them slow and awkward to rise and escape from predators.
• Statistics show that giraffes are the least likely of all prey mammals to leave a water hole without getting a drink.
• The Sauropod dinosaur, the Giraffatitan, had an unrealistic neck height, which makes it unlikely that it could have survived with such an anatomy.

Statistics:

• The giraffe's heart uses more energy than the entire body of a resting human.
• The energy cost of the heart of a resting giraffe is more than twice that of a typical mammal.
• The giraffe's blood pressure is over 200mm Hg.
• The Sauropod dinosaur, the Giraffatitan, would have required a blood pressure of about 770mm Hg to pump blood to its head.
• The energy cost of pumping blood for a typical adult giraffe is around 16% of its total energy budget.
• The imaginary creature with short legs and a longer neck would have spent a whopping 21% of its total energy budget on powering its heart.

Sources:

• [1] Mitchell, G. (2008). The Giraffe: Biology, Behaviour and Conservation. Poyser.
• [2] "The giraffe's long neck: an unexpected secret to its survival". The Conversation.