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Learn about Oligochaeta & Hirudinea classes of annelids, including characteristics, habitats, feeding habits, and reproduction. Discover fascinating facts about these segmented worms.
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Phylum Annelida Segmented Worms
About 170 N.A. species • Each segment has small bundles of tiny chaetae • Most live in silt and mud in ponds, lakes, etc. • As deposit feeders, feces deposited atop the bottom; helps keep surface aerobic • Some are very tolerant of low oxygen; Tubifex worms are long and red; can build up very high densities (8,000/m2)
Leeches • Primarily aquatic (~69 species in N.A.); only a few marine • Many are highly colored (but fade in alcohol) • Body: soft, muscular, flattened; 34 segments • Two suckers: one anterior (includes the mouth), one posterior
Natural History • Most live in shallow waters with much plants, debris, or stones; in suitable habitat, can reach density of 700/m2 • Move inchworm-style; many can swim • All feed on fluids from other organisms either as piercer-predator or as external parasite • Most feed on invertebrates • Blood suckers have 3-toothed jaws and secrete hirudinin, an anticoagulant; most feed on frogs, turtles, or fish • May not feed again for two years • Always reproduce sexually; some make cocoons; • Many require years to reach maturity • Are both predators and prey