Big Six plus one?

 Michael – Alternate Thursdays

"Well, as giraffes say, you don't get no leaves unless you stick your neck out." - Sid Waddell

Reticulated giraffe browsing
Wikipedia

In my last post I argued that the Big Five (Lion, Leopard, Elephant, Rhino, and Buffalo) should be extended to the Big Six by including the Hippo. In a comment, Everett Kaser agreed but pointed out another animal with a claim of membership – the giraffe. After initial hesitation, I realised he has a strong point. Giraffes are iconic African animals and fascinating creatures, being the tallest living terrestrial mammal in the world, and boasting extraordinary physiology. It seemed to me that at the very least they deserved their own blog post.

Southern giraffe
Giraffe Conservation Foundation 

Everyone knows what giraffe look like. Most people also know that giraffe don’t make sounds – at least not vocal ones. Giraffe can and do snort to raise the alarm at an approaching predator, and very occasionally mothers make guttural sounds to attract the attention of their kids. However, in 2015, scientists discovered that giraffe actually do make sound from their vocal chords at night, a kind of humming snore. It’s postulated that this is a communication strategy to keep in touch with the other members of the tower. (Rather delightfully, the collective noun for giraffe is a tower.) My own perspective is that giraffe don’t make sounds because they don’t have anything to say. That’s a strategy certain humans might well consider.

Speaking of sleep, giraffe generally do it standing up and only for an average of an hour a day. Lying down is just too vulnerable a position for a giraffe.

Another common belief is that giraffe have a second heart – a sort of subsidiary pump that helps push the blood up the neck to the brain. That certainly seems reasonable given the height the blood has to go. The neck alone will be between two and two and a half meters (6 to 8 feet) for an adult. Giraffes do not have particularly large brains, but they are big animals and that brain needs food and oxygen. The actual solution to this issue is even more interesting than a second heart. Firstly, the heart is large (11 kg) and very strong, generating twice the blood pressure of a human. In addition, the jugular veins feature seven one-way valves that keep the blood flowing in the right direction whatever the orientation of the neck. Quickly lifting your head from drinking at a pool or browsing a shrub can’t lead to a moment of dizziness. That sudden movement might be because of imminent danger, which is exactly when you need full alertness.

It’s obvious what the long neck is for, or is it? Giraffe get to browse higher in trees than any other animals, even elephants. That’s a feeding advantage and Darwin suggested evolution selected for long necks for that reason. A modern alternative theory is that longer necks allow males more success in necking (neck fighting) and so are sexually important. Studies suggest that the competitive feeding advantage isn't as significant as it looks.

Either way, there’s no free lunch so to speak. Although giraffe obtain most of their liquid needs from the food they eat, they do need water every few days. Now that long neck is a big disadvantage. They have to split their front legs and bow as low as they can to reach the water. It’s a dangerous position in which to find oneself in the event of a lion attack.

Reticulated giraffe drinking in Kenya
Wikipedia

If that happens, giraffe have two main defenses. The most important is flight. Despite a rather ungainly lope with the legs on each side moving together, they can reach 60 km/hr over a short distance and 45 km/hr over a longer one. Lions are sprinters. They can reach 80km/hr, but only for about 100 meters. So they have to be pretty close to get a giraffe. The second defense giraffe have is kicking. Those large hooves can produce a hell of a wallop. If the kick connects, the lion will come off second best.

There are now four recognized species of giraffe and a host of subspecies. In South Africa, giraffe are doing well with numbers growing to over 50,000. In some other countries, numbers have declined over the past decade, but now seem to be stabilizing and improving. That’s good news for the giraffes and for giraffe lovers. We must preserve these beautiful, gentle giants of the African bush.