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Annelids

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Annelids

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  1. Annelids Segmented worms. Albert Gordon Jacob Cole Jacob Cole http://wps.aw.com/wps/media/objects/1668/1708348/ebook/fig/big/3714633070.jpg

  2. Types • Oligochaeta: Earthworms and other terrestrial worms; chaetae (chitin bristles), no parapodia • Polychaeta: Marine worms that are free or tube living; parapodia • Hirudinea: Leeches and other flat annelids with no chaetae http://wps.aw.com/wps/media/objects/1668/1708348/ebook/fig/big/3714633073.jpg Albert Gordon Jacob Cole

  3. Body Formation • Annelids are Coelmates which means that they have a fluid filled cavity completely surrounded by tissue • In mature form, annelids are long with ridged segments in their skin. • Range from 1mm to 3m in length Albert Gordon http://wps.aw.com/wps/media/objects/1668/1708348/ebook/fig/big/3714633070.jpg

  4. Body Formation (cont) • Bilateral Symmetry • Hydrostatic skeleton; supported by septa between segments Jacob Cole

  5. Nervous System • Cerebral Ganglia • That’s it. They’re not exactly intellectuals… Jacob Cole

  6. Digestive & Excretory • Has mouth and anus; a digestive tract extends along length of worm. • Metanephridia (same neph as in nephron of the kidneys in humans) parallel to worm’s digestive tract filter blood and coelomic fluid. Waste secreted through exterior pores Albert Gordon Jacob Cole http://wps.aw.com/wps/media/objects/1668/1708348/ebook/fig/big/3714633070.jpg

  7. Circulatory • Closed circulatory system • Many hearts • Blood vessels wrap around the digestive tract in loops Albert Gordon

  8. Reproductive System • Cross-fertilizing hermaphrodites • Secrete mucous cocoon in which embryos develop • Some can also reproduce asexually via fragmentation Jacob Cole

  9. More Facts • Earthworms are beneficial to farmers because castings (egested materials) are valuable as a fertilizer and help recycle soil. • Hirudinea or leeches are still used in medicine today to neatly drain blood from wounds Albert Gordon Jacob Cole http://wps.aw.com/wps/media/objects/1668/1708348/ebook/fig/big/3714633074.jpg

  10. Quiz Questions • Annelids are: • pseudocoelomates • coelomates • acoelomates • Annelids live in all of the following environments EXCEPT: • seawater • freshwater • damp soil • inside the human body Jacob Cole

  11. Quiz Questions Continued • Which of the following do NOT have a closed circulatory system (select all that apply): • Nematoda • Annelida • Cephalopods • Arthropods • Annelids can reproduce by which of the following processes? • Self-fertilization • Cross-fertilization • Fragmentation • All of the above Jacob Cole

  12. Citations • All information from Chapters 32 and 33 of Textbook (Biology 7th Edition, Campbell, Reese)

  13. The End Yay!