Here's why:
* Numbers: Arthropods are incredibly diverse and numerous. They include insects, crustaceans, spiders, scorpions, and more. Estimates suggest that there are over a million species of arthropods, vastly exceeding the number of species in any other phylum.
* Abundance: Arthropods are found in virtually every habitat on Earth, from the deepest oceans to the highest mountains. Their sheer number and distribution contribute to their dominant position in the animal kingdom.
While some other phyla, such as mollusks, are also quite diverse and abundant, the sheer number and variety of arthropods make them the undisputed champions of the animal kingdom.