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Planarians
Free living flatworm; Phylum Platyhelminthes; Class Turbellaria; Incomplete digestive tract (one opening) "Pharynx"
Phylum Platyhelminthes
(Nickname = Flatworms)
4 Classes; Most are parasitic; acoelomate; reproduce asexually by fission, fragmentation or regeneration; NO circulatory /respiratory system (all cells are close to surface to exchange material)
Phylum Rotifera
(Nickname = Wheel Bearers)
Complete digestive tract (two openings); Use "flame cells" as primitive kidneys to remove excess water; Use ring of cilia around mouth "sweep" food into the organism; free living
Phylum Nematoda
(Nickname = Roundworms)
Have a Pseudocoelom; Have a complete digestive system (2 openings: mouth ->anus); Are parasitic (Ascaris, Necator, Trichinella); 1st Phylum discussed with a body cavity...
Importance of a body cavity
Fluid in the cavity helps to circulate material; Fluid in the body can make the body rigid, allowing for use of muscles (movement); Organ function improves when there is room to move in a cavity
Tegument
Thick protective layer covering the body of endoparasites; helps to keep them from being digested by their host
Proglottids
Rectangular sections of a tapeworm; Phylum Platyhelminthes; Class Cestoda
Psuedocoelom
Fluid filled cavity between the gut and the body wall
Trichinosis
Infection caused by a roundworm; acquired by eating raw or under-cooked meat
4 Classes of Flatworms
(Phylum Platyhelminthes)
Class Turbellaria (Free living)
Class Trematoda (Parasitic Fluke)
Class Monogenea (Parasitic Fluke)
Class Cestoda (Parasitic Tapeworm)
Examples of parasitic roundworms
Ascaris, Necator, Trichinella
