Oligochaetes - Feeding and Digestion in Annelids

In between annelids, the oligochaetes which comprise mostly earthworms, feed on dead, decomposing organic vegetation. They as well digest organic matter contained in the soil which they swallow during burrowing. Aquatic forms feed on detritus, algae and microorganisms. Freshwater forms like Aeolosoma collect detritus along with its prostomium. The food is collected by making a partial vacuum when the ciliated ventral surface of prostomium is placed against the substratum and the center is elevated through muscular contraction. So, the partial vacuum created releases the food particles which are swept into mouth by cilia. Some oligochaetes such as Chaetogaster catch amoebae, ciliates, rotifers and trematode larvae via the sucking action of pharynx.