Why is phylum Arthropoda considered as most successful phylum?

Phylum Arthropoda is considered as most successful phylum because of the following reasons: 

a. Phylum Arthropoda is the largest phylum of kingdom Animalia. It includes various forms like lobsters, prawns, crabs, insects, millipedes, locust, honeybees, etc. 

b. They are omnipresent (present everywhere). Arthropods show great variety of adaptations as their habitat varies from terrestrial to aquatic habitat. 

c. Several others factors also contribute to the success of the phylum which includes: 

1. The exoskeleton of arthropods is made up of tough chitinous exoskeleton. This enables them to survive on lands in almost all environment and is a great defense against predators.

2. They possess jointed appendages which allow complex movements. 

3. They exhibit moulting or eedysis. 

4. They have metamerically segmented body helping in movement around diverse environments.