Phylum: Platyhelminthes flatworms

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Phylum Platyhelminthes(flatworms)

• Greek
• "platy"' flat
• "helminth" worm

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General Characteristics

• Bilateral symmetry right/left sides
• Cephalization head (concentration of nervous
  tissue)
• Aceolomate no coelom (body cavity)
• Tripoblastic 3 cell layers
• Endoderm inside layer of cells
• Mesoderm middle layer of cells
• Ectoderm outer layer of cells

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• 5. Incomplete digestive system mouth,
  intestine, NO anus (diffuse/skin or out of mouth)
• 6. Nerve net nerves that intertwine
• 7. Monoecious both types of sex organs in one
  body (hermaphroditic)

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Class TurbellariaFresh water, free living
(nonparasitic)

• 1. Example Planaria

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Structure of Turbellaria

• Epidermis exterior layer contain pigment
• Muscle fibers run in all directions
• Parenchyma cells that fill space (no function)
• Eyespots light sensitive, 2 ocelli
• Cilia ventral surface, movement
• Mouth midventrally opening

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• g. Proboscis pharynx, sucks up food
• h. Gastrovascular cavity intestine, digests
  food
• i. Protonephridia cell that removes cellular
  waste (flame cell)
• j. Genital pore opening through which sperm and
  eggs pass

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Reproductive Organs

• Male system
• Testes make sperm
• Efferent ductules small tubes, carry sperm
• Seminal vesicle stores own sperm

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• Female System
• Ovary make egg
• Oviduct tube carry egg to vagina
• Yolk glands add nutrients (yolk) to egg
• Vagina eggs fertilized here
• Seminal receptacle large sac stores sperm from
  another worm

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• Zygote fertilized egg, laid in a cocoon
• Rhabdites make mucus movement, coating to
  protect from bacteria

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• Digestion - 1st extracellular (outside of cell
  cytoplasm), 2nd intracellular (inside cells)
• Respiration diffusion

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Nervous

• Sub epidermal nerve plexus (nerve net under
  epidermis)
• a. ladder shaped
• b. brain, longitudinal nerves, transverse nerves
• c. eyespots (light) tactile cells (touch)
  chemoreceptive cells (chemicals)
• d. statocyst (balance)
• some have rheoreceptors sense direction of
  water current

FYI commissural fibers are nerve fibers crossing
the midline and connecting the symmetrical halves
of the nervous system.
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Sketch the Planaria Anatomy
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Class TrematodaFlukes, ALL ARE PARASITIC!

• Example liver fluke
• Tegument waxy coating over body (protect it
  from the host)
• Glands produce cyst stage
• Suckers and hooks used to attach to body of
  host
• Sense organs poorly developed

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• 6. Reproductive host
• a. definitive host in which fluke reproduces
  sexually
• b. intermediate host in which fluke reproduces
  asexually

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Life Cycle of the Liver Fluke

• 1 The adult liver fluke in the human liver.
• 2 The fertilized eggs are lost with the feces.
• 3 The ciliated larva burrows into a snail.
• 4 Another type of larva, which has been
  reproduced asexually, leaves the snail.
• 5 Each of these larvae forms a resistant cyst.
• 6 The cyst remains on plants, such as water
  cress which is eaten by humans.

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Class Cestoda meaning belt

• Example tapeworms
• Structure
• Long (flat bodies)
• Proglottids segments made by budding
• Tegument waxy coating

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Adult Tapeworms in Small Intestines
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Scolex

• Head, hooks, suckers

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• Reproduction monoecious both sex organs in
  each proglottid

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Tapeworm Life Cycle

• 1 The adult tapeworm in the human gut.
• 2 Mature segments leave the gut in the feces.
• 3 The segments are eaten by a pig.
• 4 The eggs hatch into larvae in the pig's gut.
• 5 The larvae burrow into the muscles of the pig
  and form cysts.
• 6 The cysts are introduced into the human gut if
  undercooked pork is eaten.

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• Muscles well developed
• Digestive system NONE (absorbs through
  tegument no special sense organs

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How about a tapeworm diet?

• While it's unclear if this diet is more of an
  urban legend than a truth, there are reproduction
  posters touting the wonders of pills with
  tapeworm segments in them.
• The opera star Maria Callas who liked eating raw
  meat (a source of tapeworms), may have been an
  unwitting beneficiary of this weight loss plan,
  which wormed its way into popular use in the
  1920s.

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How do you know if you have a tapeworm?
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Phylum Nemertea

• Example Ribbon Worm
• circulatory system heart, blood vessels
• digestive system complete (mouth anus)
• habitat marine
• nutrition
• holozoic (ingestion of liquid or solid organic
  particles) carnivores seize prey (not
  parasitic)
• pilidium - larvae