Final answer:
Hexapods are a monophyletic group, meaning they all derive from a common ancestor and include all descendants with six legs. This monophyletic grouping is a key aspect of cladistics, which aids in understanding evolutionary relationships.
Step-by-step explanation:
Are Hexapods a Monophyletic Group?
Hexapods are indeed considered a monophyletic group, meaning they are derived from a common ancestor and include all of its descendants. In the case of hexapods, this includes all insects and related groups that have three pairs of legs. The presence of six legs in these animals is the defining characteristic of Hexapoda. Therefore, the answer to whether hexapods are monophyletic is (a) yes, they are monophyletic.
Additionally, within the context of cladistics, scientists use this system to organize monophyletic groups, which are also known as clades. For example, referring to the provided information, 'Ecdysozoa' is one such clade that includes animals which molt their exoskeletons, like the Madagascar hissing cockroaches. This organization helps in understanding the evolutionary relationships among different species.