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Annelida. Annelids. Characteristics coelomates Metamerism (= unspecialized segmentation) In the Classes based on… Parapodia Clitellium. Systems. Integument - epidermis is one cell layer with mucous gland that secrete a moist cuticle. Skeletal -hydrostatic (using coelom)
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Annelids • Characteristics • coelomates • Metamerism (= unspecialized segmentation) • In the Classes based on… • Parapodia • Clitellium
Systems • Integument- epidermis is one cell layer with mucous gland that secrete a moist cuticle. • Skeletal -hydrostatic (using coelom) • Muscle- longitudinal and circular muscles Each segments muscles are independent of the other segments. • Digestive- complete, complex, with typhlosole for absorption and chloragogen cells acting as digestive gland and excretory cells.
Systems, continued • Excretory- a pair of nephridia per segment. • Respiratory -through skin, some through parapodia; tubeworms have gills. • Circulatory- closed system, use hemoglobin as oxygen carrier. • Nervous- dorsal brain; ventral, double, solid nerve cord, with gangliain each segment. • Endocrine- hormones secreted by nervous system. • Reproductive- • Dioecious in Polychaeta; no special organs, posterior end becomes gonads. • Monoecious in Oligochaeta and Hirudinea; Clitellium.
Annelid taxonomy • Phylum Annelida (an-nel-i-da) • Class Polychaeta (poly-key-ta) • Nereis, Aphrodita, Chaetopterus, Arenicola, Amphitrite • Class Oligochaeta (ol-e-go-key-ta) • Lumbricus, Tubifex • Class Hirudinea (hi-ru-din-e-a) • Hirudo, leech • Earthworm dissection
Nereis Nereis Nereis(clam worm)
dorsal ventral Aphrodite (sea mouse)
Arenicola (Lug worm) Chaetopterus Amphitrite (plum worm) Other Polychaetes