Feather-Duster Worms
There are more than 15,000 species of annelids.
Most leeches live in fresh water. They lack appendages. Leeches may be carnivores or blood-sucking external parasites. Example: medicinal leech (Hirudo medicinalis)
Giant Earthworm
Polychaetes live in salt water; many move with paddle-like appendages called parapodia tipped with bristle-like setae. Examples: sandworms, bloodworms, fanworms, feather-duster worms
The white, bristle-like structures on the sides of this bearded fireworm are setae.
Oligochaetes live in soil or fresh water. They lack appendages. Some use setae for movement but have fewer than polychaetes. Examples: Tubifex, earthworms