Transcript PHYLUM PLATYHELMINTHES (PLAT –EE- HELL

PHYLUM
PLATYHELMINTHES
(PLAT –EE- HELL-MIN – THEEZ)
FLATWORMS
A. THE MAJORITY OF FLATWORMS ARE PARASITES.
B. THE GATEWAY PHYLUM TO
THE REST OF THE ANIMAL
KINGDOM.
CNIDARIANS:
• RADIAL
SYMMETRY
• TWO LAYERS
• LACKING MOST
ORGAN SYSTEMS.
FLATWORMS:
• BILATERAL SYMMETRY
• THREE LAYERS
• CENTRALIZED NERVOUS
SYSTEM
• SIMPLE EXCRETORY
SYSTEM.
• COMPLEX REPRODUCTIVE
SYSTEM.
• SIMPLE DIGESTIVE
SYSTEM.
Phylum Platyhelminthes
• Flat Worms –dorsoventrally (back to front)
flattened
• swims by undulations of the body
• Flatworms are the simplest animals in
which tissues are organized into real organs
and organ systems
This Phylum’s Advance
• Bilateral symmetry
• 3 tissue layers (ectoderm, mesoderm, endoderm)
= triploblastic
• Cephalization – formation of a head and “Brain”
• Nerve ladder
• Still only one opening in the gut
Cephalization
Flat worm
Simple yet Colorful
You can see why
they are called
Flatworms
Just a few Examples
The Biology of Flatworms
Cephalization refers to the formation
of a
“B
ra
in
He
ad
an
d
an
d
25%
25%
M
ou
th
25%
”
Ta
il
25%
An
us
Head and Tail
Head and “Brain”
Anus
Mouth
He
ad
A.
B.
C.
D.
Platyhelmithes is the first phylum to
have….
Ce
25%
An
us
ue
s
25%
An
ph
al
iz
ne
t
ne
rv
e
25%
at
io
n
25%
Ti
ss
A nerve net
Cephalization
Tissues
An Anus
A
A.
B.
C.
D.
Flatworms have ____ tissue layer(s).
25%
25%
4
25%
3
25%
2
1
2
3
4
1
A.
B.
C.
D.
cia
l
25%
Sp
a
et
ry
25%
As
ym
m
25%
ia
l
25%
Ra
d
Bilateral
Radial
Asymmetry
Spacial
Bi
la
te
ra
l
A.
B.
C.
D.
What type of Symmetry do
Flatworms have?
Fastest Responders
Seconds
Participant
Seconds
Participant
C. THREE CLASSES
C. THREE CLASSES
1. TURBELLARIA MADE UP OF MOSTLY
FREE LIVING
FLATWORMS. CAN
LIVE IN MARINE,
FRESHWATER, AND
DAMP TROPICAL
ENV.
• EXAMPLES:
PLANARIA
AND
POLYCLADIDS.
C. THREE CLASSES
2. TREMATODA –
KNOWN AS
FLUKES. ALL
ARE PARASITIC
AND VERY
DAMAGING.
• EXAMPLES:
ASIAN LIVER
FLUKE AND
SCHISTOSOMES.
C. THREE CLASSES
3. CESTODA –
KNOWN AS
TAPEWORMS.
ALL ARE
PARASITIC.
• EXAMPLES:
PORK, BEEF,
FISH, & DOG
TAPEWORMS.
D. THREE LAYERS
1. EPIDERMIS –
TOUGH (Outer
Layer)
2. MUSCLE –
CIRCULAR
AND
LONGITUDINAL
3. MESENCHYME
(Connective
Tissue)
E. NERVOUS SYSTEM
• SIMPLE BRAIN
FOUND AT THE
HEAD END.
• TWO NERVE
CORDS THAT
LOOK LADDER
LIKE.
F. EXCRETORY SYSTEM
• CONTAINS
FLAME CELLS.
(THE CILIA LOOKS
LIKE A
FLICKERING
FLAME)
G. REPRODUCTIVE
SYSTEM
• HERMAPHRODI
TIC.
• SEXUAL ONLY
• TAPEWORMS
CAN POSSIBLY
SELFFERTILIZE.
H. DIGESTIVE SYSTEM
Class
Feeding
TURBELLARIANS FEED ON SMALL
INVERTEBRATES
Digestion
 Mouth is used for both ingestion
& excretion.
 Mouth leads to pharynx and is
followed by the gut
Cestodes
FEED ON HOST
(INTESTINE OF A
VERTEBRATE
ANIMAL)
 Possess no gut or simple gut
 No mouth or digestive tract
 Absorb food from environment
 Digestion is intracellular
Trematodes
FEED ON HOST
TISSUE THROUGH
PHARYNX.
 Contain mouth and simple gut
 Digestion is extracellular and
then intracellular
H. DIGESTIVE SYSTEM
1. ONE OPENING THE MOUTH
2. PHARYNX AND
INTESTINES.
3. TAPEWORMS DO
NOT NEED A
DIGESTIVE
SYSTEM.
I. LIFE CYCLES
TAPEWORM
CP 25
I. LIFE CYCLES
FLUKE
CP 23
J. MISC.
1. THEY DO NOT
HAVE A
CIRCULATORY
SYSTEM OR A
RESPIRATORY
SYSTEM. USE
DIFFUSION.
J. MISC.
2. CONSIDERED ACOELOMATES
BECAUSE THEY LACK A BODY
CAVITY.
3. HAVE A HYDROSTATIC
SKELETON.
4. THEY ARE REALLY FLAT!!!