Transcript Phylum Platyhelminthes: Class Turbellaria

Phylum Platyhelminthes
April Adams
Zoology NCHS
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Phylum Platyhelminthes
• Flat worms
• Triploblastic= 3 germ
layers
• Acoelomate
• Bilateral symmetry
• Hermaphroditic
• 1 opening for digestion
• Simple nervous and
muscular systems
• Flame cells
• May be free living or
parasitic
• CEPHALIZATION
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Acoelomate
Ectoderm
Mesoderm
Endoderm
Digestive cavity is the only inner cavity,
and is not lined with mesoderm.
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Phylum Platyhelminthes: Class Turbellaria
Acoelomate
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Other Body Plans:
Pseudocoelomate
Ectoderm
Mesoderm
Endoderm
Fluid filled cavity between the endoderm and ectodermpseudocoelom
Differs from a true coelom because….
• It is not entirely lined with mesoderm tissue
• Organs are not suspended or attached to membranes
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(mesenteries)
Other Body Plans:
Coelomate
Ectoderm
Mesoderm
Endoderm
Mesoderm lines cavity between digestive
tract and body wall
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Flatworm Body Systems
• No Circulatory or
Respiratory systemssimple diffusion through
body wall
Systems Present•
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Digestive
Nervous
Reproductive
Excretory
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Flatworm Body Systems:
Digestive
Incomplete•
mouth
•
pharynx (to swallow food)
• Gastrovascular cavity
• intestine(no anus)
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Nervous System
Lateral nerve cord
anterior ganglia
sensory receptors
transverse nerve cord
Eye spot= detects
light
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Cephalization=“Primitive Brain”
Auricle
Cerebral
ganglion
Paired
nerve cords
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Excretory System
-Gets rid of
nitrogenous wastes
- protonephridia- first
kidney
Components:
-Flame cells
-Excretory ducts/tubes
-pores
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Reproductive System
•Sexual and asexual
reproduction
sexual- eggs + sperm
asexual- regeneration
•Hermaphroditesboth male (penis and
testis)
and
female organs(vagina
and ovary)
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Checkpoint
1. Which phylum do flatworms belong to?
2. Flatworms are triploblastic, what does that mean?
3. What type of body cavity do they have? Explain.
4. Flatworms are the “first” of many things in the
animal kingdom. What traits do flatworms display
that were not present in Poriferans, Cnidarians, or
Ctenophores?
5. Flatworms have the first excretory system, what is
this called? How does it work?
6. What are the three classes of flatworms?
7. Which class contains free living species?
8. How do planarians consume food?
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Kingdom Animalia
Phylum Platyhelminthes
Classes:
Turbellaria
Trematoda
Cestoda
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Class Turbellaria
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Most free-living
Aquatic
Eye spots
Regenerate if cut
in two
• Ex. Planaria
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Planarians
• Lives in fresh water
usually under leaves
and rocks
• Usually feeds on
dead or slow moving
organisms
Planarian Reproduction
Reproduction:
• Sexually:
hermaphrodites
each Planaria
gives and
receives sperm
• Asexually: can
regenerate missing
body parts (called
fission)
Detaches its tail
end and each
half regrows the
lost parts
What would happen ????
Planarians: body structures
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Nervous/sensory system: Brain-like structure
Nerve cord: carries impulses down body
Eyespots: sense light and dark
Sensory pits: line sides of head to aid in
movement and sensing surroundings
Planarians: body structures
Digestive/excretory system
• Mouth: located in center of
ventral side
• Pharynx: tube like structure
which extends from mouth
during feeding; acts like a
straw sucking up food and
carrying it to body
• Food enters mouth and
solid wastes exit mouth
• Flame Cells: remove
excess water and
nitrogenous wastes
eyespot
ganglion
ganglion
Gastrovascular
cavity
Mouth
Nerve
cord
pharynx
Flame cells
(15:00 Sea of Life- Planarian
clip)
Class Trematoda
• Trema= “hole”
• Holdfast devices
– Endoparasites
• Complex life cycle- larval
stage in one or more hosts
Primary host-juvenile/larva
stagesexual reproduction
Secondary host- adult stage,
asexual reproduction
Ex. Blood and liver flukes
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Flukes
Blood fluke life cycle:
• Eggs are released in water
from wastes of infected host
• Hatch in to swimming larvae
in water
• Larvae enter a host (like a
snail) where they develop &
mature
• Enter water again and bore
into skin of new host (man)
• From the blood stream they
bore into intestines where
they attach and feed on
blood
Schistosoma
• Blood flukes
• 200 million people
• 1 million deaths/year
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Life Cycle of a Schistosome Fluke
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Schistosome
• Cercaria have forked
tail
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Swimmers Itch
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Clonorchis sinensis
Oral sucker
Intestine
Uterus
Yolk gland
Ovary
Seminal
recepticle
Testes
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Clonorchis sinensis
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Chinese liver fluke
50 million people
Cirrhosis of liver
Diarrhea
Edema
Pain
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Fascioloa hepatica
• Sheep liver fluke
• Sheep, cattle and
man
– Weight loss
• Eat contaminated
vegetation
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Life Cycle of the Sheep Liver Fluke
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Paragonimus westermani
• Lung fluke
• Carnivores, pigs,
rodents and man
• May be fatal
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Class Cestoda: “cess pool”
• Tape worms
• All parasitic
• Live in intestines of
vertebrates
• No digestive system
• 40 feet long
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Tapeworm structures
gonad
• Scolex= “head”
• hooks and suckers to
aid in attachment to
intestine
• Proglottids: individual
parts of wormreproductive
– Each one is detachable
– Each proglottid may
contain up to 100,000
eggs which fall off when
full
– When released, they exit
with the host’s wastes
Tapeworm life cycle
• Eggs hatch in intestines of
intermediate host (pig or cow)
• Young worms burrow out of
intestine into pig’s muscle
tissue forming cysts
• Secondary host (man) eats
undercooked/raw meat
containing worm larvae cysts
• Larvae hatch and mature in
intestines
• Attach to intestines, soak up
digested food of host
• May enter bloodstream and
infect other tissues
Scolex
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Proglottid
Testes
Uterus
Vas deferens
Seminal receptacle
Ovary
Yolk gland
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Pork Tapeworm (Taenia solium)
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Taenia
saginata
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Life Cycle of the Broad Fish Tapeworm
Diphyllobothrium
latum
Source: Redrawn From Centers for Disease Control, Atlanta, GA.
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Dipylidium caninum
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Echinococcus granulosus
• Parasite of dogs
– Host
• Juveniles in sheep,
man and other
mammals
– Intermediate host
• Hydatid cyst
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Hydatid Cyst
• Cysticercus
– Juvenile stage
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Ecinococcus granulosus
• Adult stage in dog
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Checkpoint
1.
2.
3.
4.
5.
What are the three classes of flatworms?
Which class contains free living species?
How do planarians consume food?
How are flukes different from Planarians?
How are tapeworms different from
Trematodes?
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