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Nematoda Free living and parasitic forms Cosmopolitan/Ubiquitous Mostly in sediments (free living) or hosts (parasitic)

Nematoda Free living and parasitic forms Cosmopolitan/Ubiquitous Mostly in sediments (free living) or hosts (parasitic) Common in fine muds Organic rich areas Described species – 12,000+ May be up to 500,000 species total! Extremely abundant!!

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Nematoda Free living and parasitic forms Cosmopolitan/Ubiquitous Mostly in sediments (free living) or hosts (parasitic)

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  1. Nematoda • Free living and parasitic forms • Cosmopolitan/Ubiquitous • Mostly in sediments (free living) or hosts (parasitic) • Common in fine muds • Organic rich areas • Described species – 12,000+ • May be up to 500,000 species total! • Extremely abundant!! • Up to hundreds of individuals per ml of sediment • 90,000 in one rotting apple (not marine) • Hydrostatic skeleton • Longitudinal muscles only • Move by whipping back and forth

  2. Other Worms • Sipuncula (Peanut worms) • Exclusively marine (250+ species) • Most common in shallow water • Unsegmented bodies up to 35 cm long • Studded introvert used for locomotion • Cryptic • Burrow in sediments or hide in shelters • Deposit feeders • Consume detritus and microbes

  3. Other Worms • Sipuncula (Peanut worms) • Exclusively marine (250+ species) • Most common in shallow water • Unsegmented bodies up to 35 cm long • Studded introvert used for locomotion • Cryptic • Burrow in sediments or hide in shelters • Deposit feeders • Consume detritus and microbes

  4. Fig. 7.3

  5. Other Worms • Echiura (Spoon worms) • Exclusively marine (~150 species) • Deposit feeders • Feed with non-retractable proboscis • Live in burrows • U-shaped or L-shaped • Typically small but may get large in deep sea

  6. Other Worms • Pogonophora (Beard worms) • Long, thin worms (~135 species) • Most common in deep sea • No mouth or gut • Not parasitic • Anterior end of body is tuft of up to several thousand tentacles • Tentacles absorb dissolved nutrients • Symbiotic bacteria utilize nutrients to manufacture food • Vestimentifera • Large deep-sea animals • Found at many hydrothermal vents

  7. Fig. 7.17

  8. Other Worms • Pogonophora (Beard worms) • Long, thin worms (~135 species) • Most common in deep sea • No mouth or gut • Not parasitic • Anterior end of body is tuft of up to several thousand tentacles • Tentacles absorb dissolved nutrients • Symbiotic bacteria utilize nutrients to manufacture food • Vestimentifera • Large deep-sea animals • Found at many hydrothermal vents

  9. Annelida • Segmented worms • Body composed of repeated segments • Gut runs through all segments in body cavity (coelom)** • Coelom filled with fluid – hydrostatic skeleton • Longitudinal and radial muscles • Efficient locomotion and burrowing • More than 15,000 species • Cosmopolitan

  10. Annelida • Polychaeta • 10,000+ species (mostly marine) • Body segments bear pairs of parapodia • Parapodia used for locomotion, feeding • Often tipped with setae • Closed circulatory system** • Efficient transport of blood, gases • Gas exchange • Small species exchange gases across body wall • Large species have gills for gas exchange • Highly vascularized with capillaries and thin body walls

  11. Fig. 7.15

  12. Annelida • Polychaeta • Spawning – Palolo worm • Larva = Trochophore • Band of cilia around body; tuft on apex • Same larval stage in Mollusca, Echiura, Sipuncula • Diverse lifestyles • Free-living predators • Often well-developed eyes and sense organs, jaws • Burrowing deposit feeders • Burrowing suspension feeders • Tube building suspension feeders • Tubes may be calcium carbonate, agglutinated or parchment • Solitary • Colonial

  13. Annelida • Polychaeta • Larva = Trochophore • Band of cilia around body; tuft on apex • Same larval stage in Mollusca, Echiura, Sipuncula • Diverse lifestyles • Free-living predators • Often well-developed eyes and sense organs, jaws • Burrowing deposit feeders • Burrowing suspension feeders • Tube building suspension feeders • Tubes may be calcium carbonate, agglutinated or parchment • Solitary • Colonial

  14. Annelida • Polychaeta • Larva = Trochophore • Band of cilia around body; tuft on apex • Same larval stage in Mollusca, Echiura, Sipuncula • Diverse lifestyles • Free-living predators • Often well-developed eyes and sense organs, jaws • Burrowing deposit feeders • Burrowing suspension feeders • Tube building suspension feeders • Tubes may be calcium carbonate, agglutinated or parchment • Solitary • Colonial

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