PLATHYHELMINTHES

• Acetabulum - a specialized sucker for

  parasitic adaptation that responsible for

  the attachment on the host.
• Oral sucker - surrounds the mouth and is

  used to attach to the host.
• Mehli’s gland ( shell gland ) - guiding the

  ova out towards the passage ending in

  the uterus of flatworms
• Nephridiopore - remove metabolic wastes

  and excess water from the body.
• Gastrovascular cavity - Associated with digestion and the transport of nutrients
• Flame cells (protonephridia) - specialized cells responsible for

  excretion and osmoregulation.
• Auricles - contains chemoreceptors to detect food
• Eyespots (ocelli) - act as photoreceptors and used to move away from light sources
• Parenchyma - to pack the spaces between organs
• Muscular Layer:

  ❑ Beneath the epidermis lies a

  layer of muscles.

  ❑ Flatworms have both circular

  and longitudinal muscles that

  run along their body.

  ❑ These muscles allow flatworms

  to move in various ways, such

  as crawling, twisting, and

  contracting.
• Nervous System:

  ❑ Have a centralized (nervous

  ladder-like) system consisting

  of a simple brain (cerebral

  ganglia) connected to

  longitudinal nerve cords.

  ❑ Allows to respond to stimuli

  and exhibit simple behaviors.
• Characteristics

  ❑ They are hermaphrodites

  ❑ They respire by simple diffusion

  through the body surface.

  ❑ They reproduce sexually (internal

  fertilization) and asexually by

  regeneration.
• Characteristics

  ❑ Sometimes called “flatworms”.

  ❑ They may be free-living or

  parasites.

  ❑ Body is bilaterally symmetrical

  with or without cilia.

  ❑ Incomplete digestive system (do

  not have anus)
• What plathyhelminthes is this?

  Turbellaria

  
• Turbellaria - Mostly free living and aquatic.
• Turbellaria - The epidermis (outer layer) of

  turbellarians is typically

  covered with cilia, which are

  hair-like structures.
• Turbellaria - Have the ability to regenerate.
• Monogenea - Primarily ectoparasites
• Monogenea - Specialized attachment

  organs, such as hooks,

  clamps, or suckers.
• Monogenea - One-life cycle form only

  in one host
• What plathyhelminthes is this?

  monogenea

  
• Trematoda ( subclass: Aspidogastrea ) -

  ✓ Mostly endoparasites of

  molluscs.

  ✓ Possess large opisthaptor.

  ✓ Most lack an oral sucker.
• What plathyhelminthes is this?

  Trematoda aspidogastrea

  
• TREMATODA (Flukes)

  Subclass: Digenea

  ✓ Adults endoparasites in

  vertebrates.

  ✓ At least two different life-cycle

  forms in two or more hosts.

  ✓ Have oral sucker and

  acetabulum.
• What plathyhelminthes is this?

  Trematoda Digenea

  
• CESTOIDEA (tapeworms)

  Subclass: Cestodaria

  Characteristics:

  ✓ Body not subdivided into

  proglottids.

  ✓ Larva in crustaceans, adult in

  fishes
• What plathyhelminthes is this?

  Cestoidea Cestodaria

  
• CESTOIDEA (tapeworms)

  Subclass: Eucestoda

  Characteristics:

  ✓ True tapeworms

  ✓ Body divided into scolex, neck,

  and strobila; strobila composed

  of many proglottids.

  ✓ Both male and female

  reproductive systems in each

  proglottid

  ✓ Adults in digestive tract of

  vertebrates
• What plathyhelminthes is this?

  Cestoidea Eucestoda