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Transcript
Phylum Platyhelminthes
Zoology WCHS
1
Phylum Platyhelminthes
• Flat worms
• Triploblastic= 3 tissue
layers
• Acoelomate
• Bilateral symmetry
• Hermaphroditic
• 1 opening for digestion
• Simple nervous and
muscular systems
• Flame cells
• May be free living or
parasitic
• CEPHALIZATION
2
Acoelomate
Ectoderm
Mesoderm
Endoderm
Digestive cavity is the only inner cavity
3
4
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Phylum Platyhelminthes: Class Turbellaria
Acoelomate
5
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
6
(mesenteries)
Other Body Plans:
Coelomate
Ectoderm
Mesoderm
Endoderm
Epithelial lined cavity between digestive
tract and body wall
7
8
Flatworm Body Systems
• No Circulatory or
Respiratory systemssimple diffusion through
body wall
Systems Present•
•
•
•
Digestive
Nervous
Excretory
Reproductive
9
Flatworm Body Systems:
Digestive
Incomplete•
mouth
•
pharynx (to swallow food)
•
intestine(no anus)
10
Nervous System
Lateral nerve cord
anterior ganglion
sensory receptors
transverse nerve cord
Eye spot= detects
light
11
Cephalization=“Primitive Brain”
Auricle
Cerebral
ganglion
Paired
nerve cords
12
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Excretory System
-Gets rid of
nitrogenous wastes
- protonephridia- first
kidney
Components:
-Flame cells
-Excretory ducts/tubes
-pores
13
Reproductive System
•Sexual and asexual
reproduction
sexual- eggs + sperm
asexual- regeneration
•Hermaphroditesboth male (penis and
testis)
and
female organs(vagina
and ovary)
14
15
Kingdom Animalia
Phylum Platyhelminthes
Classes:
Turbellaria
Trematoda
Cestoda
16
Class Turbellaria
•
•
•
•
Most free-living
Aquatic
Eye spots
Regenerate if cut
in two
• Ex. Planaria
17
Planarians
• Free-living flatworm
• bilateral symmetry
• 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
•
•
•
•
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
• Flame Cells: remove excess water and
nitrogenous wastes
Planarians: body structures
Digestive/excretory system
eyespot
• 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
ganglion
ganglion
Gastrovascular
cavity
Mouth
Nerve
cord
pharynx
Flame cells
LABEL YOUR PLANARIAN!!!
Class Trematoda
• Parasites
• 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
22
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
24
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Life Cycle of a Schistosome Fluke
25
Schistosome
• Cercaria have forked
tail
26
Swimmers Itch
27
Clonorchis sinensis
human liver fluke
Oral sucker
Intestine
Uterus
Yolk gland
Ovary
Seminal
recepticle
Testes
28
Clonorchis sinensis
•
•
•
•
•
•
Chinese liver fluke
50 million people
Cirrhosis of liver
Diarrhea
Edema
Pain
29
30
Fascioloa hepatica
• Sheep liver fluke
• Sheep, cattle and
man
– Weight loss
• Eat contaminated
vegetation
31
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Life Cycle of the Sheep Liver Fluke
32
Paragonimus westermani
• Lung fluke
• Carnivores, pigs,
rodents and man
• May be fatal
33
34
35
Class Cestoda: “cess pool”
• Tape worms
• All parasitic
• Live in intestines of
vertebrates
• No digestive system
• 40 feet long
36
Tapeworm structures
• Scolex= head
• hooks and suckers to
aid in attachment to
intestine
• Proglottids: individual
parts of worm
– 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
39
Proglottid
Testes
Uterus
Vas deferens
Seminal receptacle
Ovary
Yolk gland
40
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Pork Tapeworm (Taenia solium)
41
Taenia
saginata
42
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Life Cycle of the Broad Fish Tapeworm
Diphyllobothrium
latum
Source: Redrawn From Centers for Disease Control, Atlanta, GA.
43
Dipylidium caninum
44
Echinococcus granulosus
• Parasite of dogs
– Host
• Juveniles in sheep,
man and other
mammals
– Intermediate host
• Hydatid cyst
45
46
Hydatid Cyst
• Cysticercus
– Juvenile stage
47
Ecinococcus granulosus
• Adult stage in dog
48
49