Practice question

Phylum Annelida unequivocally diagnosed by true metameric segmentation also called metamerism where body divided linearly into serially repeated similar segments each containing identical sets of coelomic compartments bounded by septa, paired nephridia, ganglia of ventral cord, segmental vessels, musculature derived from teloblastic growth and chaetae. Segmentation permits regional tagmosis, redundancy, flexible locomotion via peristalsis and parapodia. External annulations often correspond to septa though loss occurs in leeches. Differs from pseudosegmentation of tapeworm strobila or arthropod tagmata representing true internal repetition. Annelid segmentation co-occurs with closed circulation and ventral cord consistently observed across polychaetes and oligochaetes.