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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
Albert GordonJacob Cole
http://wps.aw.com/wps/media/objects/1668/1708348/ebook/fig/big/3714633073.jpg
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 Gordonhttp://wps.aw.com/wps/media/objects/1668/1708348/ebook/fig/big/3714633070.jpg
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
Albert GordonJacob Colehttp://wps.aw.com/wps/media/objects/1668/1708348/ebook/fig/big/3714633070.jpg
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.jpgAlbert GordonJacob Cole
Quiz Questions1. Annelids are:
a. pseudocoelomatesb. coelomatesc. acoelomates
2. Annelids live in all of the following environments EXCEPT:
a) seawaterb) freshwaterc) damp soild) inside the human body
Jacob Cole
Quiz Questions Continued3. Which of the following do NOT have a closed circulatory
system (select all that apply):a. Nematodab. Annelidac. Cephalopodsd. Arthropods
4. Annelids can reproduce by which of the following processes?
a) Self-fertilizationb) Cross-fertilizationc) Fragmentationd) All of the above
Jacob Cole
Citations All information from Chapters 32 and 33 of
Textbook (Biology 7th Edition, Campbell, Reese)
The End
Yay!