LABORATORIO:
Parte
1
Filo
Platyhelminthes
EJERCICIO
9
Goals
for
today
•  Learn
to
recognized
the
Phylum
Platyhelminthes
from
other
animals
•  Learn
the
main
diagnos=c characteris=cs
•  Learn
about
some
free‐living
and
parasi=c
species
biology
Platyhelminthes:
flatworms
These
are
acoelomate
metazoans
Lophophorata
Mollusca
Annelida
Ecdysozoa
Deuterostomia
Ro=fera
Platyhelminthes
Cnidaria
and
Ctenophora
–  Bilateral
symmetry
(dis=nct
head
and
sense
organs,
which
allows
direct
movement).
–  Third
germ
layer‐mesoderm
(triploblas=c
animals)
–  Excretory
system
made
up
of
specialized
flame
cells
and
tubules
for
removal
of
nitrogenous
waste
–  Highly
organized
nervous
and
sense
organs
in
the
anterior
part
of
the
body
(cephalizaAon)
Porifera
More
organized
than
radiate
animals
in
that:
Lophotrochozoa
Lophotrochozoa
Protostomia
Radiata
Parazoa
Bilateria
Eumetazoa
Platyhelminthes:
ClassificaAon
Classes:
Turbellaria:
•  Ciliated
epidermis
•  Paraphyle=c
group
•  Mostly
free‐living
Trematoda:
•  DigeneAc
flukes
•  SyncyAal
tegument
without
cilia
•  Leaflike
to
cylindrical
shape.
•  Organs
to
aRach
host
in
the
oral
and
ventral
part
of
the
body:
suckers,
NO
hooks
•  ParasiAc
in
all
classes
of
vertebrates
Monogenea:
don’t
have
material
Cestoda:
•  SyncyAal
tegument
without
cilia
•  Long
ribbon
like
body
shape
•  Body
divided
in
proglo=ds
•  Organs
to
aRach
host
in
the
oral
part
of
the
body:
suckers,
hooks
•  No
digesAve
system
•  ParasiAc
in
digesAve
tract
of
all
classes
of
vertebrates
Platyhelminthes:
Your
Tasks
Exercise
9A:
–  Phylum:
Platyhelminthes
–  Class
Turbellaria
•  Genus:
Dugesia
Planarias are freshwater usually
under stones or submerged leaves
or sticks. But other members of the
class are marine
Platyhelminthes:
Dugesia
1.
Take
a
slide
from
your
box
with
a
planaria:
iden=fy
the
eyespot,
aurículas,
intes=no,
faringe,
y
boca.
Water is the function of the eyespot and the auricles?
____________
Check your book for answers!
Platyhelminthes:
Dugesia
As
in
cnidarians
the
diges=ve
tract
of
turbellarians
is
a
gastrovascular
cavity,
the
branches
of
which
fill
most
of
the
body.
They don’t have an anus
so undigested food is
ejected through the
mouth! Yikes 
Platyhelminthes:
Dugesia
ReproducAon:
these
animals
are
monoecious
(hermaphrodites)
they
can
reproduce
sexually
and
asexually
by
transverse
fission
In
asexual
reproduc=on,
the
planarian
detaches
its
tail
end
and
each
half
regrows
the
lost
parts
by
regenera=on,
allowing
neoblasts
(adult
stem
cells)
to
divide
and
differen=ate.
However,
several
problems
can
occur
with
this,
so
this
does
not
happen
oXen.
In
sexual
reproduc=on,
each
planarian
transports
its
excre=on
to
the
other
planarian,
giving
and
receiving
sperm.
Eggs
develop
inside
the
body
and
are
shed
in
capsules.
Weeks
later,
the
eggs
hatch
and
grow
into
adults.
Sexual
reproduc=on
is
desirable
because
it
enhances
the
survival
of
the
species
by
increasing
the
level
of
gene=c
diversity.
wikipedia
http://www.youtube.com/watch?NR=1&v=8mXkSdIpFQ8
Platyhelminthes:
Dugesia
ExcreAon
and
osmorregulaAon:
the
excretory
system
consist
of
canals
and
protonephridia
called
flamed
cells.
Your
instructor
will
do
a
demonstra=on
for
you
to
see
these
cells
See these cells in action!
http://www.youtube.com/watch?v=Rb_3KIB4CmE
Platyhelminthes:
Dugesia
2.
Take
a
slide
from
your
box
with
a
planaria
cross
sec=on
cuts:
iden=fy
intes=no,
diver=culos
intes=nal,
lumen
de
la
faringe,
musculos
dorsoventrales.
Planaria
–
cross
sec=on
circular muscle
rhabdites
longitudinal muscle
epidermis
intestine
mesenchyme
pharyngeal pouch
lumen of pharynx
pharynx
Platyhelminthes:
Dugesia
3.
Observe
live
planarias.
Take
a
look
to
their
locomo=on.
How
does
it
use
the
head
and
auricles?
Does
it
ever
move
backwards?
http://www.youtube.com/watch?
v=VplYBDSbRmA
Platyhelminthes:
Dugesia
4.
Observe
live
planarias.
Perform
with
your
instructor
the
s=muli
experiments
described
in
page
136.
•  Response
to
touch
•  Response
to
food
•  Response
to
direc=onal
illumina=on
Write your answers this is part of the Planaria report
Platyhelminthes:
Dugesia
5.
Regenera=on
Experiment:
Some
planarians
exhibit
an
extraordinary
ability
to
regenerate
lost
body
parts.
For
example,
a
planarian
split
lengthwise
or
crosswise
will
regenerate
into
two
separate
individuals
When
a
planaria’s
head
is
cut
off,
the
remaining
tail
sec=on
will
first
regenerate
a
head.
Even
if
the
cut
is
made
very
close
to
the
tail,
the
small
tail
sec=on
first
regenerates
the
head
and
then
con=nues
to
regenerate
the
rest
of
the
=ssue
between
the
head
and
the
tail.
We
will
use
this
property
and
compare
how
long
it
takes
for
worms
cut
in
different
places
to
regenerate
a
head.
If
different
parts
of
the
planaria
body
have
equal
ability
to
regenerate,
they
should
all
regenerate
the
head
in
the
same
amount
of
=me.
If
not,
they
should
regenerate
the
head
in
different
amounts
of
=me.
The
regenera=ve
capacity
of
different
body
sec=ons
may
be
an
indicator
of
the
loca=on
of
stem
cells
called
neoblasts.
For
instance,
if
one
body
segment
has
a
low
capacity
to
regenerate,
perhaps
only
a
few
neoblasts
exist
in
the
area
around
the
cut.
Addi<onal
neoblasts
may
need
to
migrate
to
the
area
or
be
created
by
cell
division,
slowing
down
the
rate
of
regenera<on.
http://www.youtube.com/watch?NR=1&v=gZmk80fw0nc
Platyhelminthes:
Your
Tasks
Exercise
9B:
–  Phylum:
Platyhelminthes
–  Class
Trematoda
•  Genus:
Clonorchis
sinensis
Clonorchis lives in the human bile duct
(bilis) where it feeds on bile and
lacerated cells from the inflamed bile
duct very common in Asia
Platyhelminthes:
Clonorchis
1.
Observe
slide
of
Clonorchis
sinensis:
iden=ficar
ventosa
oral,
boca,
faringe,
intes=no,
ventosa
ventral,
glandula
de
yema,
poro
genital,
vesicula
semina,
ovario,
receptabulo
seminal,
teseculos,
vejiga,
poro
excretor
Platyhelminthes:
Your
Tasks
Exercise
9B:
–  Phylum:
Platyhelminthes
–  Class
Trematoda
•  Genus:
Schistosoma
mansoni
Schistosoma are blood flukes of humans that
affect ~ 200 million people in Asia, Africa, the
Caribbean (including Puerto Rico!) and South
America.
Schistosomiasis
Platyhelminthes:
Schistosoma
1.
Ciclo
de
vida:
Observe
slides
of
Schistosoma
mansoni
adults,
eggs,
and
cercariae
eggs
adults
miracidum
cercariae
You need to understand the life cycle
Platyhelminthes:
Your
Tasks
Exercise
9C:
–  Phylum:
Platyhelminthes
–  Class
Cestoda
•  Genus:
Taenia
pisiformis‐
dog
tapeworm
They are extreme parasites in that they don’t
have a digestive system. Their tegument is a
specialized epidermis that absorbs nutrients
and rejects toxins and digestive enzymes.
Live is all about maximize reproduction. In
fact tapeworms are egg factories, some
species can even fertilize their own eggs an
strategy that guarantees offspring.
Platyhelminthes:
Taenia
1.
Observe
slide
of
Taenia.
No=ced
the
scolex
and
the
body
composed
of
units
called
proglogds
which
are
not
segments,
but
units
formed
by
budding
behind
the
scolex.
proglottids
Platyhelminthes:
Taenia
1.
Observe
slide
and
model
of
Taenia
scolex
which
is
equipped
with
suckers
and
hooks.
Note
the
neck
from
which
new
proglo=ds
are
budded
off.
A= suckers
B=hooks
scolex
Platyhelminthes:
Taenia
2.
Observe
slide
and
model
of
Taenia
mature
proglo=d.
They
have
reproduc=ve
organs:
teseculos,
vaso
deferente,
poro
genital,
glandula
de
yema,
ovario,
vagina,
utero,
cordon
nervioso,
canales
excretores.
Uterus
Platyhelminthes:
Taenia
2.
Observe
slide
and
model
of
of
Taenia
gravid
proglogd,
with
the
uterus
fulled
with
eggs
or
embryos.
Where
do
you
find
gravid
proglogds?
These
proglogds
break
off
and
shed
in
the
feces
of
the
host.
Outside
the
host
the
proglogd
breaks
releasing
thousands
of
infected
eggs.
Uterus with eggs
Platyhelminthes:
Taenia
Taenia
cycle
Important
Links
Platyhelminthes
http://www.savalli.us/BIO385/Diversity/05.Platyhelminthes.html
http://es.wikipedia.org/wiki/Platyhelminthes
http://www.pbs.org/kcet/shapeoflife/episodes/hunter.html