Final answer:
The order successful in invading terrestrial environments is Diplopoda (millipedes), part of the class Myriapoda, which includes terrestrial arthropods well adapted to land.
Step-by-step explanation:
The order that has been successful in invading terrestrial environments is the Diplopoda. Creatures within the Diplopoda class, which are more commonly known as millipedes, are part of the subphylum Myriapoda. Millipedes and centipedes are terrestrial arthropods and have evolved to be successful on land.
While millipedes prefer damp environments, they are nonetheless well adapted to life on the ground with their numerous legs and segmented bodies. In contrast, members of the order Isopoda, such as woodlice, also have terrestrial species but are mainly aquatic; Decapoda, including crabs, lobsters, and shrimp, are mostly aquatic; and Collembola, or springtails, are also found in terrestrial environments but are not as widespread as millipedes.