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Worldwide distribution. Habitat : Saltwater, Freshwater, and Land. Marine. Found in benthic regions and on the surface. Phylum Annelida. Annelid “little rings”. Latin singular: Annulus Plural: Annuli Annelid
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Worldwide distribution. • Habitat: Saltwater, Freshwater, and Land. • Marine. Found in benthic regions and on the surface. Phylum Annelida
Annelid “little rings” Latin singular: Annulus Plural: Annuli Annelid • Metamerization- Division of the body into a series of repeating segments. • What other organisms, besides those in this phylum, are metameric? • What is the evolutionary advantage to metamerization?
Phylum Annelida (3 classes) • Oligochaeta- Earthworms • Hirudinia- Leeches • Polychaeta- Freshwater/Marine worms
Anatomy • All Annelids (except leeches) have setae. • Setae- Short hairs/bristles. • Function: Anchor during movement. Short setae: land Long setae: aquatic • Body segments separated by septum Septum: Internal wall • Closed circulatory system • Well-developed nervous system (brain + nerve cords)
Movement • Hydrostatic Skeleton: A skeleton made up of fluid under pressure in closed compartments. Longitudinal Muscle Circular Muscle Longitudinal Muscle Circular Muscle
Movement • Contraction of longitudinal muscles- shorten • Contraction of circular muscles- lengthen • Alternate muscular contractions: longitudinal, circular, longitudinal, circular, etc.
How are they used? Worm Ranch:http://dsc.discovery.com/tv-shows/dirty-jobs/videos/worm-rancher.htm Eating a worm:http://dsc.discovery.com/tv-shows/man-vs-wild/videos/whopper-worm.htm
Reproduction • Sexual & Asexual • Polychaets-Dioecious • Oligochaetes & Hirudinia-Monecious • Clitellum: leeches and earthworms Class Polychaets do not use clitellum for reproduction!
Class Oligochaeta (Earthworms) • Oligochaetes & Hirudinia-Monecious • Clitellum: leeches and earthworms Class Polychaets do not use clitellum for reproduction!
Class Hirudinida (Leeches) • Habitat: Primarily freshwater, few marine. Abundant in tropical regions. • Size: Most between 2-6 cm in length. • Color: Variety of colors and patterns: black, brown, red, or olive green.
Reproduction • Monecious. • After fertilization, clitellum secretes a mucous –like cocoon that receives eggs & sperm. • Bury mucous cocoon in mud. • Development process is similar to Oligochaetes.
How are leeches beneficial? • Medicinal uses: circulation, anti-clotting (Produces anticoagulant that prevents blood from clotting.) • External parasite with suckers on each end.
Class Polychaeta (Freshwater/Marine worms) • Habitat: mucous-lined burrows near low tide. Most active at night. • Size: Grows up to 30-40 cm in length. • Diet: Particle feeders. Use cilia or mucus to obtain food. Consume plankton.
Anatomy • Parapoda: Appendages of Polychaetes. Function: Locomotion & breathing.