When you come to think about it, elephant trunks are a bit strange aren't they?
Aside from a couple of less-extreme exceptions, such as with tapirs, elephant trunks are an appendage unlike anything else in the animal kingdom.
What Is an Elephant's Trunk?
The elephant's trunk is an extended nose that is fused with their top lip. They have opposable "fingers" at the end for grasping small objects. One of the ways you can tell the elephant species apart is by the number of these fingers: African elephants have two while their Asian counterparts have only one. These fingers are very strong and precise, allowing the elephant to pick up a tiny peanut, break the shell and then eat the uncrushed nut inside.
As it has no supporting bones, the up-to 2 metre long trunk must support its own weight, and the weight of anything it picks up, with the 150,000 separate bundles of muscle fibres that make up its internal structure. Rings of cartilage supports the two nostrils all the way up the trunk and they can weigh 160 kg and are able to lift objects of more than twice that!
It has also noted that some elephants have a preferred side to their trunk, just like our right or left-handedness. Some fossil mammoth tusks also show that they rested their trunks by draping them over a preferred tusk.
Feeding and Drinking
One of the main functions of the elephant's trunk is for feeding and drinking. With two tall, pillar-like legs and a large, heavy head, bending down or reaching up can be very strenuous!
The long trunk alleviates this by allowing the elephant to graze the ground or trees for food without so much as moving their head at all. They can also suck up and squirt almost 14 litres of water into their mouths.
Being strict vegetarians and having such enormous bulk, elephants need to take on and digest an incredible amount of food each day. While their wide,flat grinding teeth work the fibrous plant material into a digestible pulp, the trunk can make itself useful by independently searching and retrieving more food. No need to stop chewing to graze when you're an elephant!
With a sense of smell that is up to four times that of a bloodhound, an elephant's periscoping trunk can hunt out for friends and relatives, potential predators and food or water sources. Its length and flexibility also allows it to keenly interpret the direction of smell. Again, useful when you don't want to move your massive head around.
Socialising and Communication
By changing the shape and size of their nostrils elephants can control their trumpeting vocalisations in order to communicate with other individuals in their herd, send a message to rivals or even members of other species.
Elephants can often be seen intertwining their trunks with other elephants, specifically with friends or family, in a greeting much like a human handshake or hug.
All this brings us to how the trunk was first developed.
A short trunk, such as that of tapirs, isn't that useful in terms of grasping and as such would be hard to select for and refine over successive generations. Half a trunk isn't that useful to a fully grown elephant!
One theory suggests that the trunk could have initially evolved as a snorkel for breathing whilst submerged. This would then prove useful later when it could be utilised for the many functions mentioned above. A case of "chicken or the egg" for the pachyderm world.
Some of the elephant's closet relatives are manatees and dugongs, which have a fully aquatic lifestyle, suggesting that ancestral elephants could have possibly been more aquatic than they are today. Further evidence comes with male elephant's penises being held internally when not erect, which is something that isn't normally seen in terrestrial mammals.
To round off the argument, elephant lungs even have an adaptation for being able to withstand the pressure of water when snorkelling. Humans can only use a snorkel up to one foot long, due to pressure on their lungs, while elephants have a dense sheet of tissue in the space between the lungs and the chest which prevent their lungs from collapsing.
Perhaps elephant trunks are a throwback to a previously water-based existence and their usefulness on land is a coincidental asset which would otherwise been hard to develop? However the elephant managed to gain its remarkable trunk, I'm sure we can all agree its an enviable appendage.