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Flatworms (PowerPoint)

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					Unsegmented Worms




By Jen Borkowski
Flatworms
                  Flatworms
• Belong to the phylum platyhelminthes.
  (Plat = flat)
• There are three classes:
  – Turbellaria
  – Trematoda
  – Cestoda
  Characteristics of Flatworms
• They are acoelomates (they don’t have body
  cavities)
• They have bilateral symmetry
• Show cephalization
• Respiration through skin
• Single opening to digestive tract (pharynx)
       Class Turbellaria
• Spade-shaped head and two eyespots
• Eat protozoans for scavenge
• Flame cells remove waste
• Are hermaphrodites (have male and
  female reproductive parts)
• Can reproduce by regeneration
• Are free-living
            Class Trematoda
• Are parasitic
  flukes
• Have suckers on
  both ends of the
  body
• Can live inside or
  outside of host
          Class Trematoda
• Nervous and excretory
  systems like
  turbellarians
• Hermaphrodites
• Have complex life
  cycles
Fluke Life-Cycles
The long and complex life-cycle of the fluke can
be made easier to
understand through the use of a nonsense
mnemonic :
Every - Egg
Mirror - Miracidium (free-living in water)
Spotted - Sporocyst (in snail)
Red - Redia (in snail)
Certainly - Cercaria (free-living in water/snail)
Met - Metacercaria (in 2nd intermediate host)
Approval - Adult
          Class Cestoda
• Parasitic
• Tapeworms
• Long, ribbon-like
  bodies
• Absorbs
  nutrients from
  host
• Hermaphrodites
Tapeworm
 Anatomy
Roundworms
 Roundworms
               Roundworms
•   Belong to phylum Nematoda
•   Pseudocoelomates (fluid filled body cavity)
•   Slender bodies that taper on both ends
•   Have mouth and anus
•   Can be free-living or parasitic
Pinworms live
  in human
  intestines
Trichinosis-
a disease
from eating
infected
pork
Cysts in Contaminated Pork
               Rotifers
• Known as rotifers or wheel
  animals
• Transparent, free-swimming
  microscopic animal
• Freshwater & marine
• Have a ring of cilia around
  mouth that rotates like a wheel
  to bring in food
• Feed on unicellular algae,
  bacteria, & protozoa
                Rotifers
• Have a muscular organ
  called the mastax behind
  the pharynx to chop food
• Nervous system
  composed of anterior
  ganglia & 2 long nerve
  cords
• Show cephalization (head
  end)
• Have 2 anterior, light-
  sensitive eyespots
Rotifer Anatomy