1. The only group of Ecdysozoa that we cover in detail is the
Arthropoda. There are several other groups of Ecdysozoa (e.g.,
Nematoda, Onychophora, Nematomorpha, Rotifera), but they are
nowhere near as diverse, abundant and successful as the Arthropoda.
What single characteristic of the Arthropoda appears to account for
their success, diversity, and abundance?