Practice question

Trochophore larva is free-swimming ciliated planktonic prototroch larva characterized by equatorial ciliary band prototroch derived from trochoblasts, apical sensory tuft, ventral stomodaeum, pair protonephridia, serving as developmental link between Annelida and Mollusca. Occurs in primitive marine polychaete annelids and basal molluscan classes including Polyplacophora Bivalvia as early stage preceding veliger. In annelids develops into metatrochophore with added segments, in molluscs metamorphoses into veliger adding foot mantle shell. Presence indicates shared spiralian ancestry within Lophotrochozoa spiral cleavage emphasizing conserved larval morphology and evolutionary kinship between segmented worms and conchiferan molluscs through developmental studies.