Tusks are elongated, continuously growing front teeth that protrude well beyond the mouth of certain mammal species. They are most commonly canine tooth, as with Narwhal, , musk deer, water deer, muntjac, , peccary, and , or, in the case of , elongated . Tusks share common features such as extra-oral position, growth pattern, composition and structure, and lack of contribution to ingestion.
Other than mammals, are the only known vertebrates to have true tusks.
Function
Tusks have a variety of uses depending on the animal. Social displays of dominance, particularly among males, are common, as is their use in defense against attackers. Elephants use their tusks as digging and boring tools. Walruses use their tusks to grip and haul out on ice.
It has been suggested that tusks' structure has evolved to be compatible with extra-oral environments.
Size
Elephant tusks are sexually dimorphic, being on average larger in males than in females, and entirely absent in female
Asian elephant. Elephants with large tusks each at least in weight are known as "tuskers", sometimes also called "big tuskers" or "great tuskers". While tuskers are rare today, it is thought that they were more common in the past, prior to human impact on elephant populations. The two record holders for longest and heaviest recorded African bush elephant tusks are around long measured along the outside curve, and in weight respectively, while the longest and heaviest Asian elephant tusks are long and respectively. Even larger tusks are known from some extinct
Proboscidea, such as species of
Stegodon, Palaeoloxodon, and
Mammoth, with the longest tusk ever recorded being that of a specimen of the gigantic mastodon
"Mammut" borsoni from Greece, which measures in length, with an estimated weight of with some mammoth tusks exceeding in length and probably in weight.
The largest walrus tusks can reach lengths of over .
The longest narwhal tusks reach .
The upward curving maxillary tusks of
babirusa can reach lengths of over .
Use by humans
Tusks are used by humans to produce
ivory, which is used in artifacts and
jewellery, and formerly in other items such as
piano keys. Consequently, many tusk-bearing species have been hunted commercially and several are
endangered. The
ivory trade has been severely restricted by the
United Nations CITES (CITES).
Tusked animals in human care may undergo tusk trimming or removal for health and safety concerns.
Gallery
See also
