Ans: Arthropods are the most thriving animals and form the largest group of the Animal Kingdom. They have captured land, sea and air and are known as the three fourth of currently identified living and fossil organisms. They rank in distribution from mountain peaks to the deep sea. The thick, non-living chitinous integument develops the exoskeleton which shields the organism from predators, prevents water loss and helps to resist the temperature up to 100°C or more. They can reproduce very fast, and in less time. Cockroaches, an example of arthropods can even endure nuclear radiations. All these factors make arthropods the largest species among animals.