Sometimes we sit and ponder just how unusual many of the animals we see out here are, whether it be the stretched out lanky neck and legs of the giraffe or the hypnotising black and white striped coat of the zebra. They have all got to this point in time with their own unique design through a long strenuous evolutionary journey.
I recently watched a documentary series called “Inside Nature’s Giants”, which showcases the anatomy of a number of large animals. This documentary digs deeper into their strange adaptations both inside and out, seeking to explaining why they look the way they do.
One episode I found particularly interesting was based on the heaviest land animal on earth, weighing as much as three hippos, with six feet long ears and covered in ridiculously wrinkly skin. They may look round to you, but in fact this is not due to them being fat, rather their bloated large guts which can produce 2000 litres of methane everyday.
If you had not worked it out by now, I am speaking about elephants. Their enormous bodies and long trunks give them an unusual appearance, like no other out here.
Taking a closer look at the anatomy of elephants I will try shed light on these giants and what makes them unique.
Being so big and strictly herbivorous, they have a pretty impressive appetite to uphold and have only one small mouth within which all the food needs to go. Being able to eat their entire body weight in plant matter in about 20 days seems like an unbelievable task. Their teeth are essentially made up of one long molar, with cross-sectional ridges. These are constantly being renewed or replaced as they are relentlessly worn down while feeding. However, they have six sets of teeth that run on a ‘conveyor belt system’ of sort, as the front of the teeth wear down, the ridges break off and are replaced with new ones pushing through from the back.
Elephants stand pretty tall and being able to feed would be a challenge so they needed a means to get the food into their mouths and thus evolved the trunk, an arm like appendage with very prehensile finger-like protrusions on the end. Strong enough to lift about 300lbs but delicate enough to pick up the smallest of marula fruit. All being done with a dense collection of about 50 000 muscle fibres and absolutely no bones in the trunk. Some fibres run in a longitudinal direction in the trunk that allow the elephant to lift it up and move side to side. There are also circular muscles that allow the elephant to expand and contract the trunk as well as concertina or extend it, this is particularly helpful when stretching for branches at the top of the tree, sucking up water and spraying it into their mouths, or holding their trunk up tight when running. When thinking about our arms, it is clear that we need the bones for the support and strength, in the elephant’s case – they don’t. The trunk is made of solid muscle and adds a tremendous weight to the head resulting in a shortened neck situated close to their forelimbs for extra support.
Natural selection has given elephants the advantage of a long trunk, which helps to reach some high branches, however there is another theory stating that their trunks are mostly to help with drinking. If we look at a giraffe, they have to bend their heads right down to drink and so in this case having a smaller head is beneficial. With a smaller head the giraffe in turn have a smaller brain size. By elephants evolving a straw like trunk helping them drink, they could afford to have larger heads and brains, and therefore better cognition and thought processing. We know that elephants are intelligent but cannot specifically link this to their ability to drink with their trunk.
Constantly roaming and feeding, elephants spend most of their lives on their feet, meaning the feet play a huge role in the elephant’s survival as they deal with the colossal weight above them. The surface area of their feet is not that much bigger than the soles of an average man’s foot. So how does it carry its weight? Firstly, there is no marrow in the middle of the leg bones, making it firm to hold the weight. Secondly, its foot has a large soft cartilage pad in the heel which compresses and lifts like a spring, acting as a shock absorber. The front of the foot is structured as though it is standing on tip-toes and pushing off a huge heel-pad.
So in short, elephants evolved many ways in which to survive and occupy a niche. They evolved the trunk to help them feed and drink, however their high-fibre food then needed to be processed and in turn they evolved six sets of large ridged molars. To process their excessive diets their gut size increased too. To get enough food they needed to move around a lot and migrate, their adapted feet which could bare their weight for lengthy periods of time was the solution. If the trunk and ability to drink without bending down was a contributing factor to brain size, this would help them remember migration routes and feeding sites as well as water holes along the way. All contributing to the large, but successful body size of one of Africa’s Giants.