PHYLUM PLATYHELMINTHES Flashcards
What organisms does the phylum Platyhelminthes include?
Flatworms, flukes, tapeworms
What are the characteristics of the phylum Platyhelminthes?
Blind gut
No circulatory system or coelom (filled with spongy mesenchyme)
Excretion via protonephridia
Simple ladder-like nervous system w/ anterior brain
Tremendous capacity for regeneration and asexual reproduction
Most are hermaphroditic and internal fertilization
What is the difference between the development of archoophoran and neoophoran?
Archoophoran: show spiral cleavage
Neoophoran: have peculiar yolk-covered eggs
Describe the epidermis of the class Turbellaria.
Extensively ciliated, glandular epidermis. Multicilliated cells, produces mucus and crystalline rhabites.
Describe the differences in the gut of the organisms under the class Turbellaria.
Acoela : absent
Polycladida : complex
Tricladida : tripartite
Neorhabdocoela : unbranched
Describe the three forms of pharynx found in class Turbellaria.
Simple (acoel)
Plicate (highly eversible, polyclad, triclad)
Bulbous (pumping)
What are the adaptations of the parasitic Platyhelminthes?
Adults produce a massive number of embro
Complex life cycles (2< hosts)
- Definitive host (site of sexual reproduction)
- 1< intermediate hosts (enhance transmission to definitive host)
Describe the class Trematoda.
Includes digenic flukes
Typically has >2 hosts
Definitive host: vertebrate (inc. humans)
Live in the liver/circulatory system
Oral (&often ventral) sucker (bulbous pharynx, 2-branch gut, no anus
Chinese liver flukes has 2 intermediate hosts which are:
1) snail (extensive asexual amplification)
2) fish/arthropod (no preproduction)
Describe the class Cestoidea.
A.k.a: tapeworms
Typically has >2 hosts
Common gut parasites of all vertebrate classes
Scolex: distinctive head end with no mouth/anus
Produce many segments (proglottids) packed with infective larvae
Encyst in intermediate host (normally no asexual amplification)
