Embryos of one class in this phylum contain teloblast cells that divide asymmetrically to form blast cells. In North American forests, post-glacial invasion of a class in this phylum speeds up forest nutrient cycling. The anticoagulant hirudin is secreted by one subclass of this phylum. (*) Riftia is a genus in this phylum found on hydrothermal vents. One class in this metameric phylum has hairy chetae on limb-like parapodia. For 10 points, name 
Embryos of one class in this phylum contain teloblast cells that divide asymmetrically to form blast cells. In North American forests, post-glacial invasion of a class in this phylum speeds up forest nutrient cycling. The anticoagulant hirudin is secreted by one subclass of this phylum. (*) Riftia is a genus in this phylum found on hydrothermal vents. One class in this metameric phylum has hairy chetae on limb-like parapodia. For 10 points, name this phylum containing polychaetes and clitellates like leeches and earthworms.
Embryos of one class in this phylum contain teloblast cells that divide asymmetrically to form blast cells.