Transcript Platyhelminthes - Net Start Class

Phylum Platyhelminthes
Michael Xu & Patricia Cheng
Period 6
General Characteristics
Mostly parasitic
 They are acoelomates
 Soft and ciliated epidermis, or covered
with cuticle and with external suckers or
hooks – used to attach to host
 About 20,000 species found in marine and
freshwater
 Free living flat worms rely on camouflage.
 Flatworm can be microscopic or many feet
long and is generally very thin
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Classes
Monogenea
[flukes]
http://www.thaigoodview.com/library/contest2551/
science04/119/kingdon_animalia/images/turbellari
a4.jpg
Turbellaria
[free living flatworms]
http://www.nhc.ed.ac.uk/images/collections/invert
ebrates/parasitic/LgMonogenea.jpg
Classes Continued
Trematoda
[flukes]
http://www.emc.maricopa.edu/faculty/fa
rabee/BIOBK/01fluke.gif
Cestoda
[tapeworms]
http://faculty.clintoncc.suny.edu/faculty/michael.gre
gory/files/Bio%20102/Bio%20102%20lectures/Ani
mal%20Diversity/lower%20invertebrates/tapeworm
1.jpg
Form & Function
End
Body Plan
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Respiration
Feeding
Circulation
Reproduction
Movement
Excretion
Response
Body Plan
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Bilateral Symmetry
Body has 3 layers of tissues with organs and
organelles (triploblastic)
No internal cavity
Has a blind gut, mouth but no anus
Dorsoventrally flattened (hence, flatworms)
Cephalization, a specialization of the anterior
end of the animal, can be seen in the
clustering of sensory structures and clumps of
nerves in the head region.
The mesoderm gives rise to muscles, various
organ systems, and the parenchyma
Feeding
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Usually carnivorous,
eating a wide range of
living and dead
organisms
Some species feed on
algae
Mostly they feed on
animals and other
smaller life forms
Turbellarians have
a muscular pharynx to
up food.
Parasitic classes rely
on the host for
digestion.
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http://infusion.allconet.org/webquest/PhylumPlat
yhelminthes.html
Respiration
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Respiration occurs through diffusion, on the cellular
level
Being flat helps the diffusion
A flatworm takes in oxygen, but has no formal
respiratory system.
http://www.earthlife.net/inverts/platyhelminthes.html
Circulation
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Circulation occurs
through diffusion.
No special organs for
circulation, gut is
only body cavity
The gut is often
highly branched to
allow for more
effective
transportation and
diffusion of food to all
parts of the body
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http://www.pbs.org/kcet/shapeoflife/animals/platyhel
minthes.html
Excretion
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Incomplete digestive
system, no anus, usually
much branched
Excretory system
consists of many flame
cells connected to
excretory ducts
A flatworm has a
combination
digestive/excretory
system.
A flatworm gets rid of
wastes through the
same opening it takes in
food.
Protonephridial
excretory organs replace
anus
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http://www.ucmp.berkeley.edu/platyhelm
inthes/platyhelminthes.html
Response
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A flatworm has a very simple nervous system with
two nerve cords running down either side.
It has two simple brains called ganglia, which are
simple bundles of nerves.
It has two eyespots (ocelli) that help it sense light.
Some platyhelminthes have chemoreceptors, balance
receptors, and receptors for water movement
http://cas.bellarmine.edu/tietjen/images/platyhelminthes.htm
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Movement
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http://www.discoverlife.org/20/q?search=Platyhelmi
nthes
Some groups, like
turbellians, use cilia on
the epidermis for
locomotion on slime
trails
Parasitic worms rely on
the hosts circulatory
system for
transportation
Some species have
longitudinal, circular,
and oblique layers of
muscle under the
epidermis which help
with movement
Reproduction
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Mostly sexual
reproduction, as
hermaphrodites
Reproductive system of
each sex with gonads,
ducts and accessory
organs
Fertilization occurs
internally
Lays strings of microscopic
eggs each enclosed with
several yolk cell in a shell
Development is either
direct or with one or more
larval stages
Asexual reproduction
occurs through
fragmentation or fission.
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http://cas.bellarmine.edu/tietjen/images/platyhelmi
nthes.htm
Bibliography
TEXT
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"The Flatworms and Tapeworms (Phylum Platyhelminthes)." The Earth Life Web. Web. 20 Apr.
2010. <http://www.earthlife.net/inverts/platyhelminthes.html>.
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"Introduction to the Platyhelminthes." UCMP - University of California Museum of Paleontology.
Web. 20 Apr. 2010. <http://www.ucmp.berkeley.edu/platyhelminthes/platyhelminthes.html>.
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"Platyhelminthes." W. Fielding Rubel School of Business: Bellarmine University. Web. 20 Apr.
2010. <http://cas.bellarmine.edu/tietjen/images/platyhelminthes.htm>.
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Platyhelminthes." Oracle ThinkQuest Library. Web. 20 Apr. 2010.
<http://library.thinkquest.org/26153/marine/platyhel.htm>.
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"M31.htm." Meer Home Page. Web. 20 Apr. 2010. <http://www.meer.org/M31.htm>.
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"The Shape of Life . Platyhelminthes." PBS. Web. 20 Apr. 2010.
<http://www.pbs.org/kcet/shapeoflife/animals/platyhelminthes.html>.
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"Flatworm." Monroe County Women's Disability Network. Web. 20 Apr. 2010.
<http://www.mcwdn.org/Animals/Flatworm.html>.
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"Phylum Platyhelminthes." Infusion. Web. 20 Apr. 2010.
<http://infusion.allconet.org/webquest/PhylumPlatyhelminthes.html>.
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"Animals - Phylum Platyhelminthes." Oracle ThinkQuest Library. Web. 20 Apr. 2010.
<http://library.thinkquest.org/28751/review/animals/3.html>.
PICTURE
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"Platyhelminthes - Flatworms, Tapeworms, Flukes." Discover Life. Web. 20 Apr. 2010.
<http://www.discoverlife.org/20/q?search=Platyhelminthes>.
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สาระ ความรู้ ข่ าวสาร ความบันเทิง ของชาวมัธยมศึกษา และประถมศึกษา : Knowledge for Thai Student | ThaiGoodView.com.
Web. 20 Apr. 2010. <http://www.thaigoodview.com>.
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Natural History Collections: Home. Web. 20 Apr. 2010. <http://www.nhc.ed.ac.uk>.
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Estrella Mountain Community College. Web. 20 Apr. 2010. <http://www.emc.maricopa.edu>.
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Clinton Community College. Web. 20 Apr. 2010. <http://faculty.clintoncc.suny.edu>.