1. 一、清明节安排
1.放假时间：
4月5日（周四）至7日（周六）放假调休，共3天。
2.课程安排：
4月8日（周日）上4月6日（周五）的课。
Term list 3&4 for next week

2. Protostomes, Lophotrochozoa, Part 1
lophophore
trochophore larva

5. Platyhelminthes: acoelomate “radiates” with organs.
Triploblastic
Ectoderm
Mesoderm
Endoderm
Gut
Why are they called “flatworms”?
Why are they flattened?
Blank slide for drafting a title slide.

6. A 2nd germ layer, endoderm, is added by gastrulation.
archenteron
Ectoderm - epidermis
Mesoglea - non cellular
Ex: jellyfish
Endoderm and ectoderm first introduced by Lankester, and mesoderm by Huxley.
blastopore
Endoderm - gastrodermis

7. The 3rd germ layer, mesoderm, arises from the endoderm
The 3rd germ layer, mesoderm, arises from the endoderm. Triploblasts are subdivided based on an 2b. internal cavity.
Acoelomate Pseudocoelomate Coelomate
Ectoderm
Mesoderm
Endoderm
The evolution of the coelom is associated with many functional advantages. Primarily, the coelom provides cushioning and shock absorption for the major organ systems. Organs housed within the coelom can grow and move freely, which promotes optimal organ development and placement. The coelom also provides space for the di􏰄usion of gases and nutrients, as well as body 􏰅exibility, promoting improved animal motility.

8. In the past, some zoologists grouped bilaterian animal phyla based on characteristics related to the coelom for practical purposes, knowing, and explicitly stating, that these groups were not phylogenetically related.

9. Bilateral animals display cephalization. Why?
Blank slide for drafting a title slide.
Flame cells [protonephridia]

10. As protostomes, they display spiral cleavage and mosaic development.
Simple / Branched intestine with proboscis. Anus variably present. but no anus.
Hermaphroditic
The nervous system is a nerve ladder with anterior ganglia.
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12. Flatworm membership is in flux.*
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Egger et al. 2009
PLoS One

13. As currently defined, platyhelminths include
turbellarians
Class Cestoda
Class Trematoda
Class Monogenea
Gyrodactylus salaris
Blank slide for drafting a title slide.
theaquaculturists.blogspot.com
Biodidac.bio.uottawa.ca

14. Turbellarians represent 15% of the flatworms.
Extraordinary regenerative abilities
Ciliated ventrum
& mucus
Martin 1978, 5000x
Polychoerus carmelensis
rhabdite
packets
Free-living
5 mm – 50 cm
Aquatic / terrestrial
Turbellarians may have evolved independently of the remaining flatworms.

17. The remaining flatworms are all parasites, show reduced or missing flatworm traits, but all have a tegument.
Parasitism evolved once!
Neodermis : no cilia & synctial
K. Rohde
Blank slide for drafting a title slide.

18. Monogeans are ecto-parasites of fish
Monogeans are ecto-parasites of fish. What must all ecto-parasites be able to do?
Heterobothrium
Opisthaptor
Mouth
Blank slide for drafting a title slide.

19. Cestodes are internal parasites characterized by a scolex and proglottids.
Taenia sp.
microthrix on surface
Blank slide for drafting a title slide.
Germinative zone

20. Each proglottid contains reproductive and excretory structures
Each proglottid contains reproductive and excretory structures. It is not true segmentation.
uterus
testes
genital pore
excretory canal
sperm duct
In animals, metamery is defined as a mesodermal event resulting in serial repetition of unit subdivisions of ectoderm and mesoderm products.[1] Endoderm is not involved in metamery. Segmentation is not the same concept as metamerism. Segmentation can be confined only to ectodermally derived tissue, e.g., in the Cestoda tapeworms. Metamerism is far more important biologically since it results in metameres, also called somites, that play a critical role in advanced locomotion.
Truly segmented animals would be considered to have organs that were repeated, or having a body composed of self-similar units,
yolk [vitelline] gland
ovaries
# not fixed, differ in age, differ in development, independent units

21. Each intermediate host allows for a different developmental stage, but there is 1 definitive host.
Blank slide for drafting a title slide.

23. Useful applications of tapeworms?
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25. Trematodes are flukes and have multiple suckers.
pharynx
oral mouth
intestine
ventral sucker
uterus
yolk glands
Spine in tegument
Blank slide for drafting a body slide.
testes
excretory pore 25

26. Trematodes have unique adaptations to find, recognize , and access hosts.
Egg with
miracidium
metacercaria
Sporocyst / redia
Blank slide for drafting a title slide.
cercaria

27. Because of their ability to find and access multiple hosts, they often have complicated life cycles.
Clonorchis
Chinese liver fluke
M. Strike & K. Jones, salinella.bio.uottawa.ca
Trematodes have a greater specificity for the first intermediate host and less specificity as development progresses.

28. Most trematodes are monoecious but some species are dioecious and display sexual dimorphism.
Gynecophoric canal in the male into
which the female lies.
Schistosoma
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29. Schistosomiasis is perhaps #2 global disease with respect to the number of people infected [200 milion].
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No redia or metacercaria
in these blood flukes

30. Acanthocephalans are endoparasites with a hook-bearing proboscis
Acanthocephalans are endoparasites with a hook-bearing proboscis. A pseudocoelomate, eutelic, lophotrochozoan.
En.wikipedia.org
Echinorhynchida
Blank slide for drafting a title slide.

31. Rotifers and spiny-headed worms are sister-groups sharing a specialized tegument: non-molted, synctial epidermis.
Scrubmuncher.wordpress.com
trophi of mastax
toe
Rotifer.acnatsci.org
corona
Blank slide for drafting a title slide.

32. Ribbon worms [Phylum Nemertea] are also lophotrochozoans, but eucoelomates by schizocoely.
Cerebratulus marginatus
Eversible proboscis (+/- stylus)
in rhynchocoel
Like flatworms:
Flame bulbs
Ciliated epidermis
Circular/longitudinal muscles
Blank slide for drafting a title slide.
Unlike flatworms:
Complete digestive system
Closed loop vascular system
Paranemertes peregrina
© R. Kordas 2009

34. Oncomiracidium [larva]

35. Flatworms are acoelomate bilateral animals, perhaps the first to have developed a mesoderm, or are they ?
Reductionism of lophotrochozoan?
original state
Blank slide for drafting a title slide.
Both pathways represented by flatworms?