Aristotle was one of the first philosophers to develop a system for classifying living organisms. His system was based on the idea that all organisms can be divided into two main groups: animals and plants. Animals were further divided into two subgroups: vertebrates and invertebrates. Vertebrates are animals that have a backbone, while invertebrates do not. Insects were classified as invertebrates.
Aristotle also divided animals into four classes based on their mode of locomotion:
1. Pedestrians: animals that walk or run on land
2. Aquatic animals: animals that live in water
3. Flying animals: animals that fly
4. Reptiles: animals that crawl or slither
Birds and bats were both classified as flying animals, while insects were classified as pedestrians.
Aristotle's classification system was a major breakthrough in the study of biology. It was the first system that attempted to organize all living organisms into a coherent and hierarchical structure. Aristotle's system laid the foundation for modern taxonomy, which is the science of classifying living organisms.