Armadillos are unique mammals known for their bony plates of armor and long, sticky tongues used to catch ants and insects. But another distinctive feature of armadillos is their surprisingly high number of teeth – they can have over 100 teeth, much more than most other mammals their size. So why do armadillos need so many teeth?
An Evolutionary Adaptation for Insect-Eating
The main reason armadillos need a lot of teeth is because of their specific insectivorous diet. Armadillos primarily feed on ants, termites, and other insects, which requires specialized teeth to break through the hard exoskeletons of these bugs.
Armadillos belong to the order Cingulata, which also includes extinct glyptodonts and pampatheres. Cingulates evolved tough, protective armor and specialized teeth for crushing and grinding insects. The cingulate teeth are simple in shape (all molars, no canines or incisors), but they have developed into an elaborate system of 7-17 teeth in each jaw quadrant, for a total of 28-100 or more teeth.
In comparison, human adults have just 16 teeth in each jaw quadrant – 32 total. Other insect-eating specialists like anteaters and aardvarks have fewer than 10 teeth in total. But armadillos have the most elaborate tooth structure within the cingulate order. Their numerous similar teeth work together as a unit to grind up insects.
Dental Formula of Armadillos
The number and type of teeth that an animal species has is known as their dental formula. Here are some examples of dental formulas:
- Human: 2 incisors, 1 canine, 2 premolars, 3 molars x 2 quadrants = 32 total teeth
- Nine-banded armadillo: 7-8 molars x 4 quadrants = 28-32 total teeth
- Giant armadillo: Up to 17 molars per quarter for 100+ total teeth
- Aardvark: 5 premolars, 3 molars x 2 quadrants = 16 total teeth
Armadillos have a simple homodont (all teeth the same) dental formula of just molars, while humans have four different tooth types. But armadillos have more molars packed into their jaws to create an efficient insect-grinding surface. The giant armadillo has taken this to the extreme with up to 17 molars in each rear jaw quadrant!
Molar Types
Looking closer, the armadillo grinding teeth can be divided into three main molar types:
- Deciduous premolars – The initial baby teeth
- Permanent premolars – Replace the deciduous teeth
- Permanent molars – The main grinding teeth
The permanent molars are the largest and most complex as they bear the brunt of the chewing forces. Towards the back of the jaw, the molars become bigger and flatter, forming ideal crushing surfaces.
Tooth Replacement Abilities
Another key reason armadillos can have so many teeth is that they can continuously replace lost or damaged teeth throughout their lifetimes.
Most mammals can only replace teeth once, with baby teeth being replaced by permanent adult teeth. But some species like armadillos have taken tooth replacement even further.
Armadillos have complex diphyodont dentition where new teeth are constantly growing at the back of the jaw to replace old worn-out teeth that get pushed forward and eventually fall out. They can produce up to 8-10 replacement teeth for every socket.
This ability for continuous tooth replacement means armadillos can maintain their high number of grinding teeth. It also compensates for the extreme wear and tear caused by their tough insect diet.
Tooth Development
Armadillos have specialized dental anatomy that facilitates their tooth replacement ability:
- Deep jaws provide room for developing replacement teeth
- Their tooth roots are closed-ended and annual, allowing new teeth to develop inside
- The permanent molars slowly drift forward, while new molars emerge behind
- Exfoliation scar folds help push old teeth out as new ones develop
This system of drifting molars and continuous development from the rear allows armadillos to keep their teeth going strong.
Eruption Sequence
Researchers have found that armadillo teeth tend to erupt in an unusual sequence compared to other mammals:
- In most mammals, incisors and canines erupt first.
- In armadillos, the 4th premolar erupts first instead.
- The 3rd and 2nd premolars follow, along with the 1st molar.
- Finally the incisors, canines and 1st premolars erupt last.
This irregular sequence gets the all-important grinding molars up and running first. The front biting teeth develop last since they are not essential for early insect eating.
Impressive Jaw Strength
The structure of the armadillo jaw also allows them to generate impressive bite forces. Their jaws are designed for grinding and crushing strength, not speed.
Some key adaptations include:
- Large masseter and temporalis muscle attachment sites on their lower jaw and skull bones. These provide large powerful chewing muscles.
- Wide zygomatic arches (cheekbones) to anchor sizable temporalis muscles.
- Broad, heavy mandibles and skull bones for stability under pressure.
- Simplified hinge-like TMJ jaw joints that sacrifice quick mobility for pure crushing power.
The powerful jaw muscles and stable skull bones help armadillos bite down hard on insects – likely harder than other mammals their size. This helps crush the hard shells and bodies of ants, termites, beetles, etc.
Bite Force Measurements
Research on the nine-banded armadillo found they produce bite forces around 46 psi (pounds per square inch). This is stronger than many similar-sized mammals:
- Nine-banded armadillo: 46 psi
- Virginia opossum: 37 psi
- Rabbit: 35 psi
- Groundhog: 40 psi
It also rivals or exceeds some larger carnivores:
- Armadillo: 46 psi
- Raccoon: 45 psi
- Coati: 37 psi
The armadillo has exceptional bite strength for its size thanks to its specialized jaws. The force generated helps pulverize all those insects!
Habitat and Feeding
Understanding more about armadillo habitats and feeding helps explain their unusual teeth:
Habitat
- Found throughout Central and South America up into southern North America.
- Most species prefer warm, tropical environments with plenty of rainfall.
- They prefer forests, grasslands, or scrublands. Areas with loose soil make digging for food easier.
Food and Foraging
- Insects like ants, termites, beetles make up 80-90% of their diet.
- They also eat worm, millipedes, snails, reptiles, amphibians and some plant material.
- Forage by rooting through soil with snout to find insects; also tear open logs and mounds.
- Use long sticky tongues to lap up insects quickly once uncovered.
- Powerful jaws help crack open different bugs’ hard exteriors.
So armadillos have adapted to feast on the high abundance of social insects across Central and South America. Their unique dentition helps them take full advantage of this plentiful food source.
Q&A
Q: How many teeth do armadillos have?
A: Armadillos have between 28-100 teeth, depending on the species. This number is much higher than similar-sized mammals. The nine-banded armadillo has around 32-36 teeth.
Q: What types of teeth do armadillos have?
A: Armadillos have simple homodont dentition, meaning they only have one type of tooth – cheek teeth called molars. They have no incisors for biting or canine teeth for tearing.
Q: How are armadillo teeth adapted for eating insects?
A: Armadillo teeth are well-suited for crushing the hard exoskeletons of insects. They have a large number of repetitive, grinding molar teeth. Their jaws also produce strong bite forces.
Q: How do armadillos replace lost or damaged teeth?
A: Armadillos continuously replace their teeth throughout life as new teeth erupt at the back of the jaw. They can produce up to 10 replacement teeth for every socket.
Q: When do armadillos get their adult teeth?
A: Unlike many mammals, armadillos’ grinding molars tend to erupt first. The front incisors and canines erupt last. This helps the molars develop quickly for early insect eating.
So in summary, armadillos have evolved an impressive number of grinding molar teeth in order to consume their insect diet. Their simple but highly effective dentition is just one of the unique specializations that allow armadillos to thrive on ants, termites, and other bugs. Their continuously replacing teeth help maintain their chewing capacity for life. Studying the armadillo tooth system provides an interesting example of how mammalian teeth can adapt for specific diets and lifestyles.
