Figure 23.18: Diversity among the Annelids (A) “Fan worms,” or “feather duster worms,” are sessile marine annelids that grow in chitinous tubes, from which their tentacles extend and filter food from the water. (B) Pogonophorans live around hydrothermal vents deep in the ocean. As in fan worms, their tentacles protrude from chitinous tubes. They do not possess a digestive tract, however, and obtain most of their nutrition from endosymbiotic bacteria. (C) This hermaphroditic freshwater leech is brooding a clutch of fertilized eggs.