Zoology Lecture 13
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Zoology Lecture 13
Zoology Lecture 13
What is paculiar about platyhelminths yolk and and ova
that yolk is not depositied in the ova but instead ova and seperate yolk cells are packaged as capsules
What is this sort of egg like pattern known as
Ectolecithal eggs –Neöphora
________ and some other turbellarian Orders have the more conventional pattern of ova that include yolk.
What is the more traditional yolk pattern known as
Spiral cleavage with determinate development.
–1d progeny form ____________
anterior epidermis & NS.
muscle & mesenchyme of pharynx
mesentoblast forms gastrodermis& most mesenchyme.
Development in the Neöphora, Planaria
Does the Development in the Neöphora, Planaria have typical spiral cleavage if not why not?
change in the egg yold relationship has led to different patterns then conventional spiral cleavage
As cleavage starts, two populations of yolk cells what are they
Large, spherical lipid rich yolk cells
Motile, RNA-rich fusiformyolk cells.
As cleave continues, the motile yolk cells ________ around the _______ and forms a syncytium.
After formation of the yolk syncytium, continuing cleavage leads to two sets of _________.
The first population forms a cryptic larva that is mostly pharynx-gut and feeds on the yolk syncytium. just saing
Later the second population becomes the ___________ which replace the tissues of the cryptic larva and form the _______ of the juvenile worm.
Parasitic classes just saying
The parasitic classes have __________, and protonephridial, ________ and reproductive systems like turbellarians.
They have _________ organs of one type or other.
In addition to being Neöphora, the parasitic classes at some stage in life loose the _________and develop a new outer covering
–_________making them the Neodermata.
Tegument 1 ust saying
What are the two regions of the tegument
1. outer anucleate synctium
2. inner nucleate region (high metabolic turnover)
Where does the tegument originate from? what is it fromed from? hwat is this inital layer called at embryogeniss?
the tegument (from mesodermal origin) replaces the epidermis (from epidermis during embryogenisis)
Are all teguments the same?
No. Surface topography varies from group to group
What does a tegument consist of roughly
a glycocaly layer overtop of a gelatenous (?) layer with a basment membrane which was created and connected toa number of open cell bodies with nuclei inside each one
What types of interspecies relationships would you expect to see with flaties
commensalism, mutualism and definitly parasitism
what -odes would you expect to see in parasitic relationships specifically
Define Primary or definitive host
Host in which the adult parasite is found
Define Secondary or intermediate host
host in which the juvenile or larval stages are found
Vector - acts as an agent that actively transmits the parasite to another host.
What are three fairly obvious ecological barriers to the establishment and the growth of the parasite
Physiological barriers –pH –pCO2, –pO2 –temperature –osmotic concentration –nutrient availability –failure to excystor hatch in gut
Biotic barriers –primary host defences (macrophages) –secondary host defences (immunity) –interspecificinteractions (host/parasite, parasite/parasite) –intraspecific(crowding) –host/parasite signals that affect parasite maturation
What is the "rule" for parasite feeding or nutrietion
Just because trans-tegumentrary is possible does that mean no parasites have a gut?
no. some parasites do have a gut
What methods does tapeworms use in order to obtain nutrition
diffusion, active transport, pinocytosis and phagocytosis
What is an irony of a parasite taking nutrution from host?
the fact that the parasite will dump waste products back into the host for the host to deal with
are reproductive systems between the three parasitic classes similar or dissimilar? do they resemble any other class?
they are similar. They resemble the triclads
What type of reprodction (dimporphism etc) are the parasites? what do they produce as a final product
They are all hermaphrodidic and they produce an ectolecithal egg
What does monogenean infect
What do indirect life cycles allow for when it comes to larvae
indirect life cycles allow for larval amplification
fig 8.2 showing the hosts including human as the definitive host as well as a fish and a snail that flukes must use. a sheep can also be a host
more life cycles to view