Platyhelminths Flashcards
Classes of platyhelminths?
Turbellaria, Monogenea, Digenea*, Aspidogastrae, Cestoda*
Trematoda?
Digenea + (Monogenea + Aspidogastrea aquatic) (flatworms)
Cestodes are
tapeworms
General platyhelmith features
Flattened, bilaterally symmetrical, tegument, tipoblastic, acoelomate, hermaphroditic, flame cells, cephalisation, blind ended (trematodes) or no gut (cestodes)
Features of Digenea lifecycle?
-Indirect -generations of sexual (adult) and asexual (larval) generations in alternate host. -2+ hosts
Veterinary significance of Digenea?
Bottle jaw, paramphistomiasis, acute and chronic fascioliasis
Medical significance?
Schistosomosis, oriental fish borne liver flukes
Adult Digenea features
-Non-segmented -suckers (oral, ventral or posterior) +/- spines -Dig tract; no anus - mostly hermaphrodites
Digestive system arangement
What are the osmoregulatory system cells?
Protonephridal Flame cells
Reproductive system outline
General lifecycle of Digenean
Digenea egg features
- possess a ‘cap’ or operculum +/- spines
- aquatic of terrestrial hatching
- contains miracidium or unembryonated when passed
Which egg?
Schistosome - spine to assist getting through blood vessels
Features of Miracidium
Aquatic - ciliated epithelium
Highly sensory (light, temp, salitity, chemotaxis, negaitive geotaxis) -> must find snail
Retractable apical papilla - sensory nerve endings, apical glands with enzymes for penetration, muscular contractions = penetrate the snail.
What is the sporocyst/rediae?
- asexual reproductive stage - ‘Sac like’ structure (with germinal cells) within the snail - produce daughter sporocysts/rediae
Features of cercariae
- escape from snail
- actively motile (swim tail first)
- may penetrate host (DH or 2nd IH)
- Mechanical head movement and protease enzymes force entry into a host
