There are between 9000-12400 species of these segmented worms, including the common earth worm. The body plan is divided into repeating segments, separated by thin membranes called septa. This repeating body plan is called metameric.
Annelids have a complete digestive tract and circulatory system.
Most Annelids belong to the Class Polychaeta. Polychaetes burrow in sediments or live in tubes. The species shown here creates a tube out of mucous secretions mixed with sand grains. The feathery appendages at the anterior end are used for food capture, or may be vascularized to act as gills for gas exchange. Found in tough, white tube.