Final answer:
The best phylum to demonstrate segmentation is Arthropoda, which includes diverse species with segmented bodies and jointed appendages. Phylum Annelida also shows segmentation but lacks jointed limbs. Arthropods such as insects are easily accessible for observation and provide a clear example of the segmented body plan.
Step-by-step explanation:
If you are aiming to demonstrate an example of segmentation to visiting students, the phylum Arthropoda would be the ideal choice to illustrate this concept. Animals within phylum Arthropoda, such as insects, spiders, and crustaceans, exhibit a segmented body plan with jointed appendages. This phylum is immensely diverse with numerous species easily accessible for observation. For example, insects like beetles or grasshoppers can be handled and observed closely to see the segmentation and how the appendages are attached to the body segments.
When comparing segmentation in phylum Annelida and phylum Arthropoda, it is important to recognize that Annelida, including earthworms and leeches, also exhibits true segmentation or metamerism. This segmentation is characterized by repeating units, both externally and internally, and is associated with the presence of chaetae or bristles made of chitin. However, unlike arthropods, annelids do not have jointed appendages. Annelids display more uniform segments that contribute to their locomotion and organ systems distribution.