7. What are the reasons that you can think of for the arthropods to constitute the largest group of the animal kingdom?
The reasons for arthropods being the largest group of animals are as follows:
1. Presence of tough cuticle for protection of the body. It also helps in tolerating diverse terrestrial conditions.
2. Presence of striated muscles for quick movements
3. Tracheal respiration for direct supply of oxygen as in insects
4. Presence of jointed appendages for performing diverse functions
5. Well developed nervous system and sense organs.
6. Presence of pheromones for communication