L 12 - platyhelminthes & nemertea Flashcards
turbellaria
extensively ciliated, glandular epidermis.
only some show spiral cleavage
turb =?
roiling disturbance
cilia cause water to move.
Turb =mutliciliated cells produce mucus called?
rhabdites - pocket of mucus. they use this to crawl on, capture prey and copulate
turb = how do they alter body shape?
how do they move?
body shape w circular, longitudinal, dorsovental. move w ciliea.
NS of turb?
ladder-like NS. distinct anterior ganglion. Main L/R trunks
sensory organs present in turb?
eyes - light sensitive
chemoreceptors - detect stuff around you.
gut types in turb
simple/sac-like
tricladida (3-branched), polycladid (many branches)
where is mouth?
feeding?
mid-ventral, sometimes anterior mouth.
predatory and scavengers = digest externally, secrete enzymes on food, take into gut. branched gut takes nutrients where it needs to go in body.
no anus, regurgitated thru mouth.
some have symbiotic algae
repro of turb
hermaphroditic.
fertilziation internal - copulation or traumatic insemination.
produce hard-shelled cocoon around egg.
2 groups of yolk placement
- inside egg cytoplasm = endolecithal = archoophora
2. around outside of egg = lectolectithal = neoophora
3 parasitic taxa in platyhelminthes
trematoda
monogenea
cestoda
shared traits in 3 parasitic taxa with turb
dorsoventral flat body, blind gut, protonephridia, neoophoran, coputlation
differences btw turbellaria and 3 parasitic taxa
eyes (parasitic lack), epidermis has cilia
syncytial epitheliumm - protective from host
what is syncytial epithelium
share common cell , membrane lack nuclei
more than one intermediate host allows?
enhancement of transmission to definitie host.
simplification via asexual repro.
behaviour of intermediate changed to increaes likelihood of being eaten by final host
trematoda
- hosts?
- feeding?
flukes - parasitic. typically > 2 hosts. oral sucker; 2-branched gut. feed by taking tissue into mouths and pumping pharynx. definitive host usually verteebrate.
CNS in trematods
brain simplified ladder-like NS.
KNOW TREMATODE LifE cycLE
draw this
cestoda
tapeworms
> 2 hosts. final host = vertebrate.
head = scolex. w hooks and suckers.
no mouth/gut - nutrients taken in by pinacocytes + diffussion. produce segments (proglottids) - packed w fertilized eggs - leave w feces.
KNOW CESTODA LIFE CYCLE
draw this
phylum nemertea
ribbon worms
- predatory, mostly marine.
nemertea - shared traits with flatworms
multiciliated glandular epidermis, protonephridia, ladder-like NS asexual repro + regeneration, spiral cleavage.
nemertea - different traits compared to flatworms
body circular, complete gut. closed circulatory system. separate sexes, proboscis in rhynchocoel.
how nemertea capture prey
predatory, shoot out proboscis via hydrostatic pressure. proboscis tipped w stylets - punctre prey like harpoon.
copulation/repro of nemertea
development post-fertilization
male lack copulatory appendage
extrude egg and sperm simultaneously for external fertilization. sometimes sperm released in mucus on body, swim over to femal and fertilize egg internally.
- development direct or indirect.
- larva pinch off to become juvenile - j eats larva.
clade spiralia
spiral cleavage. determinate cleavage (cell X will turn into Y - no other cell will. meaning no twins)
platyhelminths AKA =?
phylogeny?
flat worms
unresolved phylogeny; unresolved polytomy
platyhelminthes - mode of feeding? habitat?
free-living & parasitic
- marine, freshwater, terrestrial
4 major taxa in platyhelminthes
trematoda -parasitic
monogenea -p
cestoda - p
turbellaria - free-living (paraphyletic, group of convenience)
platyhelminthes - protostome characters they have
spiral cleavage
blastopore => mouth
multiciliated cells
platyhelminthes lack protostome characters:
have blind gut
no circulatory system/coelom
simple ladder like NS , no circumesophageal connectives
excretion by protonephridia (important for osmoregulation)
reproduction of platyhelminthes
regeneration & asexual repro = budding, fission, fragmentation.
hermaphroditic - internal fertilization.
