1. Two Large, Continuously Growing Incisors:
* This is the most defining feature. Rodents have a pair of large, chisel-shaped incisors in both their upper and lower jaws.
* These incisors grow continuously throughout their lives and are constantly worn down by chewing.
* The lack of canines creates a gap, known as a diastema, between the incisors and the molars.
2. Specialized Molars:
* They have molars with high crowns and enamel ridges, designed for grinding tough plant material.
3. Strong Chewing Muscles:
* Rodents possess powerful masseter muscles, enabling them to gnaw on hard objects like wood or bone.
4. Short, Fused Jaw Bones:
* Their lower jawbones are fused, providing greater stability and strength for chewing.
5. Usually Small in Size:
* While there are exceptions, most rodents are relatively small, ranging from mice to rats to squirrels.
6. Varied Diets:
* Though many are herbivores, their diets vary greatly depending on the species. Some are omnivores, while others are insectivores.
7. High Reproductive Rate:
* Rodents often have multiple litters of young per year, contributing to their success as a group.
8. Wide Geographic Distribution:
* Rodents are found in nearly every terrestrial habitat across the globe, adapting to diverse environments.
Beyond these physical traits, rodents are also known for their:
* Cleverness and adaptability: Many species are known for their problem-solving abilities and can quickly adapt to changing environments.
* Importance in ecosystems: They play crucial roles in ecosystems, acting as prey for larger animals, dispersing seeds, and contributing to nutrient cycling.
* Economic impact: Some species, like rats and mice, can be considered pests and cause significant damage to crops and property.
In summary, while there are some exceptions, the combination of their unique teeth, specialized jaw structure, and other shared features makes rodents a distinct and successful order of mammals.