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If you have seen a deer or horse chewing their food, you may have noticed that they eat with a sidewards motion. I wanted to learn about herbivores’ teeth and what I found was very interesting.

Herbivores are animals that primarily eat plants as their main diet. Plants wear out teeth much faster than meat. Plants are not as nutritious as meat, so herbivores need to spend longer feeding. Unfortunately, their teeth do not last as long as carnivores.

Herbivores have incisors that cut the plant before the molars chew it. Some species also have canine teeth as well.

Many herbivores eat grass containing silica salts in the leaves and stem. The salt damages the teeth as it wears them down when the animal cheats.

Teeth are covered in enamel, and the herbivore quickly grinds down the enamel, exposing the dentine underneath. Carnivores do not have this problem, as the enamel stays intact. Dentine wears down quicker than enamel, with the enamel appearing as ridges.

Herbivores use their incisors to bite the plant before the molars chew and grind it before swallowing. Herbivores have two sets of teeth; the incisors are the biting teeth, and the molars are the chewing teeth. A diastema, a small gap, separates the two sets of teeth.

Many different animals have different ways of eating. In this article, I look at a few of these.


Horses have the most teeth out of all herbivores. Horses and ponies have up to 40 teeth with six incisors along the top of the jaw used to cut the grass by biting against the lower jaw’s incisors.

Although slow, a horse’s grazing in its lifetime wears the enamel down, revealing the dentine.

Horses chew grass at the back of their mouth using molars. The molars are long with ridges of enamel above the dentine and glue. The glue not only keeps the root where it should be but also fills any crevices and gaps in the sides of the molars.

If you have seen a horse chew, you will know that they chew in a sideways motion. Horses grind their molars against each other to break down the plant cells. Once the cells are broken down, the animal’s saliva and digestive juices help break down the plant to ingest the nutrients.

Male horses also have some teeth that females do not. When fighting for females in mating season, these canine teeth are used to bite other males.


Deer and some other ungulates aid their digestion by chewing their food twice to get all the nutrients. As with horses, deer use their incisors to cut the plant material, although the incisors are only along the lower jaw. Deers have a pad in the top jaw, which helps to reduce wear on the incisors when eating.

Deers have three incisors on each side of the lower jaw and a canine. The canine is not used for fighting as in horses but helps cut plant material. Fallow and roe deer do not have the extra dog on each side of the lower jaw. Deer have 12 molars, which they use to grind plants.

Small Herbivores

Smaller mammals have incisors and molars but do not eat plants like deer. Rabbits, hares, and rodents do not have any canine teeth. The dentine quickly wears out, keeping the incisors short as they only have enamel on the front edge.

Although the incisors wear out quickly, they also grow at the same rate. For example, rats grow their incisors up to 6 inches yearly and have fewer teeth than most other mammals except mice and voles.

Sidewards Chewing

All herbivores can move their jaws in a sideward motion, which helps them to eat. Carnivores can only bite up and down, not side to side. Larger herbivores such as deer need to eat a considerable amount of grass and plants to survive, and chewing sidewards allows them to chew quickly before swallowing. This will enable them to eat quicker when in the open and exposed to potential predators.

Later, when the deer are not exposed, they will regurgitate the plant, also known as cud. Giving the plant another chew before swallowing the animal ensures it gets all the necessary nutrients from the plant. This is known as chewing the cud.