Phylum Platyhelminthes / Nemertea/ Nematoda/ Rotifera

Phylum Platyhelminthes (Flatworms)

   Class Trematoda Ex: Flukes 

   Class Cestoda Ex: Tapeworm 

   Class Turbellaria Ex:Dugesia 

   Class Monogenea Ex: Polystoma 

Phylum Nemertea (Ribbon Worm)

Phylum Nematoda (Round Worm)

Phylum Rotifera (Rotifers) 

General Body Plan 

General Anatomy 

Anatomy of Dugesia or Planaria

Source: http://shsapbiop3-taxa.wikispaces.com/animalia-platyhelminthes

Anatomy of Rotifer

Source http://www.emc.maricopa.edu/faculty/farabee/biobk/biobookdiversity_7.html

Life Cycles of Parasitic Worms 

Class Trematoda 
Clonorchis sinesis (Liver Fluke)
Shelled Embryo-->Miracidium-->SNAIL-->sporpcyst-->redia--> cercaria-->metacecaria in FISH's muscles --> HUMAN's liver

Source: http://bio390parasitology.blogspot.com/2012/02/immigrants-from-afar-clonorchis.html

Schistosoma mansoni (Blood Fluke)
Shelled Embryo-->Miracidium -->SNAIL-->sporocyst-->cercaria--> HUMAN's liver

Source: http://www.cab.unimelb.edu.au/cab_schisto.htm

Class Cestoda 
Taeniarhynchus saginatus (Beef's Tapeworm)
Shelled Embryo (in proglottid)--> consumed by cattle-->onchospheres in blood-->cysticercus (bladder worm) in beef muscle --> HUMAN's intestine

Source: http://www.esu.edu/~milewski/intro_biol_two/lab__10_platy_nemat/taenia_scolex.html

Class Nematoda 
Ascaris lubricoides (Intestine roundworm)
Shelled Embryo (in feces)--> Shelled larvae develop on soil--> shelled larvae ingested by humans with food or water--> larvae emerge in duodenum then enter blood stream--> in lung, move to trachea, esophagus--> HUMAN's intestine.

Source: http://bca.org/gallery/bioimages2010.html

Ancyclostoma duodenale (Hookworm)

Shelled Embryo (in feces)--> Larvae developed in soil--> Larvae grow-->larvae attach, penetrate skin, enter blood stream--> in lung,enter alveoli-->bronchi-->esophagus--> HUMAN's intestine.

Source: http://www.dpd.cdc.gov/dpdx/HTML/ImageLibrary/G-L/Hookworm/body_Hookworm_il2.htm

Enterobius vermicularis (Pinworm) 

In Human's intestine and cecum-> females migrate to anus at night--> deposited shelled embryos causes itching-->fingernails and clothing pick up shelled embryos--> reinfection of self. food, water, air, dust--> hatch in duodenum. 

Source: http://dailyparasite.blogspot.com/2010/06/june-10-syphacia-obvelata.html

Source: Blake Barron's Lab Manual
Useful Link: http://siera104.com/bio/flatworms.html