Elephants get six sets of molar teeth throughout their lifetime.
These molars are used to chew and grind the vast amounts of food an elephants elephants on a daily basis. As the ridges on these teeth become worn down at certain intervals throughout an elephants life they are replaced with another molar that grows at the back of the jaw and pushes forward, almost like a conveyor belt.
Once they wear down the sixth set of molar teeth an elephant has no further way of processing it’s food and will lose its ability to adequately feed itself. This usually happens in it’s very late 50’s - early 60’s and is natures way of removing older elephants from the population.
An elephants tusks are not molars but giant modified incisor teeth. Elephants will most often develop two sets of tusks during their lifetime. The first set of very small tusks referred to as 'milk tusks' often fall out between 6 - 12 months of age which are then followed by the main pair of tusks. These tusks then grow continually throughout an elephants life.
The rate of tusk growth in a mature elephant is between 15 - 18 centimetres per year, however general wear & tear erodes some of this growth.
Tusks are made up of a compound called dentine - which is commonly referred to as ivory.
image credit : A.C Gomes
Dentine is a bone like tissue found in the teeth of many mammals that is made up of 80% inorganic materials and 20% water & organic materials.
The dentine substance is created by cells at the outer surface of the inner pulp cavity called odontoblasts which create and lay the ivory in a specific cross-hatch pattern which distinguishes elephant ivory from the dentine of other mammals.
Both male and female African elephants grow tusks (in Asian elephants only the males grow tusks), although the tusks of males grow considerably larger. By the age of twenty the tusks of most males exceed the tusk weight & length of much older females.
As the tusks get larger they become a useful tool in prying bark off trees, digging for salt deposits & roots and uncovering water in dry riverbeds.
The hardness, strength, elasticity and feel of ivory has long been favoured by carvers and seen ivory manufactured and sculptured into many forms such as furniture, musical instruments, sculptures and figurines, billiard balls, jewellery, name(signature) seals and even chopsticks.
The largest tusks on official record are the world famous Kilimanjaro tusks that belonged to a bull shot on the slopes of Mount Kilimanjaro (Tanzania) in 1898. They weighed in at 105.4kg's (left tusk) and 103.6kg's (right tusk).
They were taken to Zanzibar the centre of the ivory trading world at the time where a representative from Arnold Cheney & Co, a powerful New York based ivory importing firm purchased the tusks for almost $5,000, then the highest sum ever paid for a pair of elephant tusks.