(from Latin incidere
, "to cut") are the first kind of tooth
in heterodont mammals
. They are located in the premaxilla
above and mandible below.
In many herbivorous
mammals, such as the human
and the horse
, they are adapted for shearing sharply. In cats
, the incisors are small; biting off meat is done with the canines
and the carnassials
. In elephants
, the upper incisors are modified into curved tusks
, just as is the case with Narwhals
, where normally one of them develops into a straight and twisted tusk. The incisors of rodents
grow throughout life and are worn by gnawing.
Number and types of incisors
normally have eight (8) incisors, two of each type. The types of incisors are:
Among other animals, some other primates
, cats and horses have twelve. Rodents
have four. Rabbits and hares (lagomorphs
) were once considered rodents, but are distinguished by having eight--1 small pair, called "peg teeth" is directly behind the most anterior pair.