One of the most prominent questions in the engineering industry is how to build something that lasts. The biomechanics of elephant locomotion gives an example of near engineering perfection stemming from biology itself – with each foot supporting thousands of pounds of weight consistently and without failure while also maintaining mobility.
Read more: The 21,000 lb Question – How Elephants Defy Logic Through LocomotionThe Elephant in the Room
So how is this possible? The unique structure of an elephant’s foot allows for this gravity-defying phenomenon to become a reality. An elephant’s foot is made up of several different structures and materials that work together to distribute the loading caused by the elephant’s impressive weight. The main components include the lower limb/foot bones themselves, elastic and collagen fibers, adipose tissues, predigits, and perhaps most importantly, cushions of fat expanding the bottom part of the foot.
Taking it Step by Step
Elephants are extremely heavy and wide-roaming creatures. They are almost constantly on their feet, and therefore need a suspension system that is long-lasting and withstanding of tremendous loads. Unlike human feet where the bones are articulated almost exactly how you might expect by viewing them externally, elephant bones are actually pointed in a tip-toed formation, with fatty pads acting as cushions around the skeletal elements. Walking on their tiptoes allows for gravitational forces to be spread out through the thick layer of padding under each bone and also reduces stress on the rest of the structural system within the elephant’s body. Also conversely to humans, elephants have a “sixth toe,” or a predigit, which aids in the elephant’s movement as well. These toes were discovered in 1706, when a Scottish surgeon dissected an elephant for the first time in record. Analysis of fossils belonging to elephant ancestors show that this sixth toe evolved around 40 million years ago as elephants expanded in size and became land based. This predigit starts as a piece of cartilage, but gradually hardens to bone as the animal grows in size and weight. Its purpose is to support the heel of the fat pad – further helping with suspension and aiding in stabilization.
Getting Into the Meat of the Issue
Arguably the most important piece of the elephant foot in terms of failure prevention is the cushions of fat upon which the inner structure of the elephant rests. Designed to absorb and distribute mechanical forces – these dynamic tissues operate in a system of compression and tension in order to minimize harmful stresses to any one part of the elephant’s body. As the elephant places weight on one of their feet, the adipose tissues in the fat pads compress and spread out in order to maximize force dispersion. Collagen fibers and elastic fibrous connective tissues also within these cushions are pulled in tension – resisting the lateral deformation which has a stiffening effect. This stiffening effect helps to limit deformation of the tissue which prevents failure/injury due to heavy loading in the foot. These fat pads can expand up to a whopping 20% – effectively protecting even the outermost parts of the elephant’s foot. This process is similar to pressing down on a memory foam pillow – as you lower your hand the pillow compresses and spreads out to absorb the impact, but as you lift your hand and remove the weight, the pillow goes back to its original shape, ready to be compressed again.
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