Annelids Segmented worms. Albert Gordon Jacob Cole http://wps.aw.com/wps/media/objects/1668/1708348/ebook/fig/big/3714633070.jpg Jacob Cole 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/obje cts/1668/1708348/ebook/fig/big/3 714633073.jpg Albert Gordon Jacob Cole 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 http://wps.aw.com/wps/media/objects/1668/1708348/ebook/fig/big/3714633070.jpg Albert Gordon Body Formation (cont) Bilateral Symmetry Hydrostatic skeleton; supported by septa between segments Jacob Cole Nervous System Cerebral Ganglia That’s it. They’re not exactly intellectuals… Jacob Cole 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 http://wps.aw.com/wps/media/objects/1668/1708348/ebook/fig/big/3714633070.jpg Albert Gordon Jacob Cole Circulatory Closed circulatory system Many hearts Blood vessels wrap around the digestive tract in loops Albert Gordon Reproductive System Cross-fertilizing hermaphrodites Secrete mucous cocoon in which embryos develop Some can also reproduce asexually via fragmentation Jacob Cole 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 http://wps.aw.com/wps/media/objects/1668/1708348/ebook/fig/big/3714633074.jpg Albert Gordon Jacob Cole Quiz Questions 1. Annelids are: a. b. c. 2. pseudocoelomates coelomates acoelomates Annelids live in all of the following environments EXCEPT: a) b) c) d) seawater freshwater damp soil inside the human body Jacob Cole Quiz Questions Continued Which of the following do NOT have a closed circulatory system (select all that apply): 3. a. b. c. d. 4. Nematoda Annelida Cephalopods Arthropods Annelids can reproduce by which of the following processes? a) b) c) d) Self-fertilization Cross-fertilization Fragmentation All of the above Jacob Cole Citations All information from Chapters 32 and 33 of Textbook (Biology 7th Edition, Campbell, Reese) The End Yay!