Of all the extraordinary features that the elephant displays, perhaps the most unique and astonishing is the most incredible feat of evolutionary engineering – the trunk. A nose, an arm, a hand, a voice, a straw, a hose and much more. The elephant’s trunk is surely the most versatile and useful appendage on the planet!
What is the trunk and how does it work?
The trunk is the fusion of an elephant’s upper lip and nose and was formed over millions of years of evolution. It is a long, prehensile tube with two nostrils running down the centre and a mass of flesh, muscle, fat, nerves blood and connective tissue that can weigh up to 140kgs.
The key to the trunk’s success is an extraordinary network of muscles which are divided into external and internal. There are four big external muscles, covering the top and side of the trunk, another along running along the bottom and a pair that sit on either side of the trunk’s base. These control the trunks big movements – up, down and side to side. The internal muscles are found in a highly complex network known as fascicles. An entire trunk can contain up to 150,000 fascicles as evidenced by Hezy Shoshani and his team at The Elephant Research Foundation who dissected and painstakingly counted 148,198 of the tiny fascicles on an Asian elephant’s trunk. The fasciles are arranged along the entire length of the trunk like spokes on a bicycle wheel. By working together with the external muscles, they give the trunk the extraordinary flexibility we witness when watching elephants.
The trunk tip is one of the key differences between African and Asian elephants. The African elephant has two fingers while the Asian has only one. This affects the way they use their trunks; while the African will actually grasp an object with between its fingers, the Asian will use more of a scooping movement and hold objects against the underside of the trunk. This does not appear to limit the Asian elephant’s ability to manipulate objects.
The trunk tip is packed with nerve endings and according to research by Rasmussen and Munger in 1996, is the most sensitive tissue ever studied!
Dexterity and Sense of Touch
All elephants display great dexterity with the trunk, although it takes baby elephants a number of years to become truly expert in their use. It is amusing to see the antics of newly born calves as they try to get used to the limb dangling in front of them. Often they get in a real muddle and become extremely frustrated.
Once mastered though, the trunk has no equal in the animal kingdom for dexterity, manoeuverability and strength. This allows it to perform the even the most delicate functions which range from the ability to pick up a small coin from a flat surface to lifting weights in excess of 250kg.
The trunk also allows elephants to reach up, down and into difficult spots that they cannot see which is of particular importance as elephants, unlike other browsing and grazing animals, do not use their teeth to directly feed. Instead an elephant will use the trunk’s strength and flexibility to rip grass from the ground or fodder from a tree and then place it in its mouth. Trunks also allow an elephant to to be selective about what they have gathered – for example, it is common for an elephant to use its trunk to shuck corn before eating the succulent cobs after disposing of its fibrous wrapping!
An Elephant’s Sense of Smell
Given that they have the largest nose in the world, it is perhaps not surprising that elephants are thought to have the best sense of smell of all animals. The sense of smell is probably the most important of their senses. If you observe elephants for any length of time, you will notice that the tip of their trunks are constantly moving, testing the smells in the air in every direction as we might perhaps use our eyes.
Monitored wild elephants have shown that they are able to pick up smells over distances of several miles, giving them a useful early warning system of approaching danger. Elephants also commonly smell each other and each other’s body secretions to obtain valuable chemical knowledge about their companions.
When something more than smell is required, elephants use the trunk tip as a chemical receptor – allowing them to obtain information about other elephants. They gather chemical information by touching the trunk tip against a substance, commonly urine, faeces or temporal glad secretions. The trunk tip is then pressed against the roof of the mouth to the vomeronasal or Jacobson’s organ where the chemical is analysed for the information it possesses. This is known as the Flehmen Response.
Relationship with Water
Contrary to what is often believed, the elephant does not use its trunk to drink through. It does however play an important role in the act of drinking. The elephant uses the trunk to draw water and then sprays it into the mouth. A typical trunk can hold around four litres of water, although studies have shown that the trunk of a big bull can hold up to 10 litres!
The ability to spray water is also an important part of basic hygiene and health care. Elephants use the trunk as a shower with various pressure settings. It can either send a power blast jet of water or offer a more gentle alternative!
Elephants also use the trunk to transfer a layer of dust or mud to their bodies which protects them from insect bites or the ravages of a hot sun. When elephants are very hot and water is not readily available, they will often put their trunks in their mouths, obtain large amounts of saliva and spray it on their bodies. It is not advisable to stand beside or behind and elephant when they are engaged in this activity!
The trunk is an essential tool for social behaviour and virtually all close elephant interaction involves the trunk. They use them to touch, stroke, explore, caress and embrace. A mother will wrap her trunk protectively around her baby, close family members and friends will put the tips of their trunks in each others mouths, juveniles will play by trying to wrap up their friend’s trunk in theirs and potential mates will touch and feel the more private areas of the object of their affection.
The trunk is also used in more confrontational situations both aggressive and defensive. It is used to chastise, discipline or control. An elephant will often wave its trunk or hold it in the air as a warning of aggressive intent. However when confronted by an elephant, the real danger sign is when he rolls the trunk up and tucks it under his chin. This signals that an elephant is preparing to charge.
Vocalisation and Sound
Although it is not the only way they communicate acoustically, elephants can use their trunks to produce a range of sounds. They do this by modifying the size of their nostrils once air has passed over their larynx. Trunk-produced sounds can range from a low snort to high pitched squeaks of excitement or a deafening full blown trumpet.
Although not a vocalisation, elephants also use the trunk to produce a particular warning sound, rapping their trunks on the ground to produce a resonating rumble. This is often used by mothers when they are concerned by threats to their young.
Vital for Life
The reason a charging elephant tucks his trunk out of harm’s way is to protect it from damage. A functioning trunk is absolutely vital for an elephant’s survival. It is a remarkable organ and just one of the reasons that elephants are such exceptional animals.