Microspines in the alimentary canal of arthropoda, onychophora, annelida

The presence and variation of microspines within the foregut and hindgut of the taxa Arthropoda, Onycophora, and Annelida were presented. Microspines appear to be sympleisiomorphic to the Arthropoda sensu stricto. Unispinose microspines constitute the original ancestral condition, and these have been retained and variously modified within the classes to aid in filtering ingested food, food movement through the gut and retain symbionts, and possibly protect the cellular linings of the gut in particulate food eaters.