[This was written by Fran Siebrits and published online by Wild Magazine http://www.wildcard.co.za, 2012]

Picture by Romi Boom

Because
of their vegetarian diet, zebras have no use for the killing-sharp
canine teeth so essential to carnivores. These canines, however, are
quite developed in male zebra … and quite useful too.

Reader Marie Shatkovsky queried the following description in Wild
19 winter 2012: “Most zebra stallions live in bachelor groups where
they often display their rank through orderly fighting that includes
displays of the canines.”Canines are synonymous with piercing
and killing, hence their importance to meat-eating mammals. So it seems a
bit odd to learn that herbivores need such teeth at all. But teeth are
not only used for eating.

Teeth in mammals
It
was many millions of years ago, in the Mesozoic era, when major changes
occurred in the teeth and jaws of mammals. Teeth became specialised to
perform various functions ranging from seizing and cutting to tearing
and grinding.

There are four types of teeth in mammals:
•    Incisors with sharp edges for snipping and biting
•    Canines with long conical crowns for piercing (often reduced or missing in herbivores)
•    Premolars with compressed crowns for shearing, slicing, crushing and grinding
•    Molars with compressed crowns for shearing, slicing, crushing and grinding

Unlike
their reptilian friends, mammals do not continuously replace their
teeth throughout their lives. Deciduous (or milk) teeth are replaced
only once; these include the incisors, canines and premolars. Molars, on
the other hand, are never replaced and are the only permanent set which
must last the lifetime.

Zebra teeth
Related
to the domestic horse, zebras are grazers. They have strong upper and
lower incisors for cropping grasses. Their molars are adapted for
grinding with a broader and higher crown useful when processing
silicate-rich grasses. A zebra’s canine teeth are reduced in size and,
like all herbivores, do not play a prominent role in food gathering and
processing.

Teeth are the only form of sexual dimorphism
(difference between the sexes) in zebras. Male zebra have spade-shaped
canines, which they use in rivalry fights with other stallions.

A
male wild boar also has modified canines, just like male zebras, which
are quite pronounced and used as weapons. In other mammals other teeth
have become specialised. The tusks of elephants, for example, are
modified upper incisors used for defence, attack and rooting.

Sources
Integrated Principles of Zoology (thirteenth edition). Hickman, Roberts, Larson, l’Anson, Eisenhour. 2006. MsGraw-Hill. p604-605, 693-694.
http://www.britannica.com/EBchecked/topic/656157/zebra