Transcript File

Phylum: Platyhelminthes
(flatworms)
Greek
"platy"' flat
"helminth" worm
General Characteristics
1. Bilateral symmetry –
right/left sides
2. Cephalization – head
(concentration of
nervous tissue)
3. Aceolomate – no
coelom (body cavity)
4. 3 cell layers
5. Incomplete digestive
system – mouth,
intestine, NO anus
(diffuse/skin or out of mouth)
6. Nerve net – nerves that
intertwine
7. Hermaphroditic – both
types of sex organs in
one body
1. Endoderm – inside layer
– Fertilized egg (zygote) is
of cells
laid in cocoon
2. Mesoderm – middle
8. Respiration – occurs
layer of cells
through diffusion
3. Ectoderm – outer layer
of cells
Class Turbellaria
Fresh water, free living (nonparasitic)
Example: Planaria
Structure of Turbellaria
a. Epidermis – exterior
layer; contain pigment
b. Muscle fibers – run
in all directions
c. Parenchyma – cells
that fill space (no
function)
d. Eyespots – light
sensitive, 2 ocelli
e. Cilia – ventral
surface, movement
f. Mouth – midventral
opening
g. Pharynx – sucks up food
h. Gastrovascular cavity –
intestine, digests food
i. Flame Cell – cell that
removes cellular waste
j. Genital pore – opening
through which sperm and
eggs pass
Anatomy
Class Trematoda
Flukes, ALL ARE PARASITIC!
1.
2.
3.
4.
5.
6.
Example: liver fluke
Tegument – waxy coating
over body (protect it from the
host)
Glands – produce cyst stage
Suckers and hooks – used
to attach to body of host
Sense organs – poorly
developed
Reproductive host
a. definitive host – in which
fluke reproduces sexually
b. intermediate host – in
which fluke reproduces
asexually
Life Cycle of the Liver Fluke
1 The adult liver fluke in the
human liver.
2 The fertilized eggs are lost
with the feces.
3 The ciliated larva burrows
into a snail.
4 Another type of larva, which
has been reproduced
asexually, leaves the snail.
5 Each of these larvae forms a
resistant cyst.
6 The cyst remains on plants,
such as water cress; which is
eaten by humans.
Class Cestoda
meaning: “belt”
1. Example: tapeworms
2. Structure
a. Long (flat bodies)
•
Muscles well developed
b. Proglottids – segments made by budding
•
Sex organ found here
c. Tegument – waxy coating
•
Absorbs nutrients – No digestive system
d. No special sense organs
Adult Tapeworms in Small Intestines
Scolex
• Head, hooks, suckers
Tapeworm Life Cycle
1 The adult tapeworm in
the human gut.
2 Mature segments
leave the gut in the
feces.
3 The segments are
eaten by a pig.
4 The eggs hatch into
larvae in the pig's gut.
5 The larvae burrow into
the muscles of the pig
and form cysts.
6 The cysts are
introduced into the
human gut if
undercooked pork is
eaten.
World Longest Tapeworm…
The longest tapeworm ever
removed from a human
came out of Sally Mae
Wallace on September 05,
1991.
In all, doctors pulled 37 feet
of tapeworm out of Sally
Mae Wallace's body
through her mouth.
If you find all of this
disgusting, be glad you're
not a whale as tapeworms
in whales can grow up to
120 feet long.
How about a tapeworm diet?
• While it's unclear if this diet is more
of an urban legend than a truth…
• There are posters touting the
wonders of pills with tapeworm
segments in them.
• The opera star Maria Callas who
liked eating raw meat (a source of
tapeworms), may have been an
unwitting beneficiary of this weight
loss plan, which wormed its way
into popular use in the 1920s.
Phylum Nematoda:
The Round Worms
Characteristics
•There are over 80,000 species of round worms
•Some are aquatic, most are parasitic
1. Cylindrical,
unsegmented, with
tapering ends.
2. Pseudocoeloemates
• Cavity partially lined
with tissues from
mesoderm
3. Digestive Tract with
TWO openings – mouth
and anus
4. Diffusion through body
walls
5. Simple nervous system
with some sense organs
6. Effective hydroskeleton
and musculature
7. Reproduce SEXUALLY
– most speces have
separate sexes
• Females can produce
~100,000 eggs a
day.
Parasitic Nematodes:
Hookworm
•Eggs hatch outside
the body and develop
in soil.
•Use sharp hooks and
teeth to burrow into
skin and enter
bloodstream
•Travel from blood >
lungs > intestines
•Suck blood = weakness
and poor growth
Heartworms
Guinea Worms:
•Tiny infected water flea are drunk up from
standing water
•Inside human, grows and matures up to 3 ft
•After a year, worm emerges through painful
blister
Filarial Worm
(causes elephantiasis)
•Live in
Blood and
Lymph vessels
•Transmitted
through
biting
insects
(mosquitoes)
•Blocking of
lymph
passages =
elephantiasis
Trichinosis
•Caused by Trichinella
roundworm
•Adults live and mate in
hosts
•Females burrow into
intestine and release larvae
•Larvae travel in
bloodstream, burrowing
into organs/tissues
causing terrible pain
•Larvae form cysts that
become inactive
Ascarid Worms
1. Spread by eating
contaminated food with
Ascaris eggs
2.
Eggs hatch in intestine,
burrow in walls, and enter
blood vessels
•
Carried through BV to
lungs, spread into air
passages/throat, get
swallowed and cycle
begins again
3. Ascaris matures in host
intestine and produce large
#’s of eggs
•
Leave body in feces
 These are the worms that we
“de-worm” in puppies and kittens