How are worms
different?
ALL WORMS are:
INVERTEBRATES (no backbone)
PROTOSTOMES (blastopore mouth)
COELOM TYPES:
Flatworms = acoelomates
Round worms = Pseudocoelomates
Segmented worms = coelomates
FLAT WORMS
(PLATYHELMINTHES)
TAPEWORMS
PLANARIA
FLUKES
FLATWORMS
(PLATYHELMINTHES)
Planaria
(Cross-eyed worm)
DIGESTIVE/CIRCULATORY
SYSTEMS
One big cavity for
digestion and circulation
= Gastrovascular cavity
Only one opening- in and out through mouth
MOUTH in middle on
VENTRAL SURFACE
NERVOUS SYSTEM
SHOW
SIMPLE
LEARNING
CEPHALIZATIONCEREBRAL GANGLIA with
2 VENTRAL NERVE CORDS
PLANARIA
RESPIRATORY
Exchange gases through skin
REGENERATION
(Ability to regrow
lost body parts)
REPRODUCTION
HERMAPHRODITES- SEXUAL
trade sperm with other worms
lay eggs in protective sac on rocks
Can also use REGENERATION for
ASEXUAL reproduction
FLATWORMS
PLANARIA
• Free living
• Digestive cavity with one opening/mouth in middle of
body
• Open circulatory system (shared Gastrovascular cavity)
• Flame cells for excreting nitrogen waste
and excess water
• Cephalization-Cerebral ganglia with 2 nerve cords
• Hermaphrodites with sexual reproduction
(asexual reproduction using regeneration)
• Eye spots sense light and dark
• NO tegument or cuticle
FLATWORMS
(Nematoda)
FLUKES
Leaf shaped body
Covered by TEGUMENT
for protection for host
immune system
DIGESTIVE/CIRCULATORY
shared GASTROVASCULAR cavity
similar to Planaria
MOUTH at anterior end
NOT middle of body
SUCKERS (anterior and
ventral) help it hold on
and suck blood
NERVOUS
CEPHALIZATION
Cerebral ganglia with 2 nerve cords
No eyes
EXCRETORY
Flame cells remove nitrogen waste &
regulate water
FLUKES
REPRODUCTIVE
Most hermaphrodites
Some have separate sexes
(Blood fluke-Schistosoma)
Complicated life cycle with 2 hosts
EX: Blood fluke-Schistosoma
Adults live in human- sexual reproductio
Larva live in snails – asexual reproduction
HOW DO THEY
INFECT HUMANS?
Eggs pass
out in feces
Primary host:
Human
Larva burrow into skin
Intermediate
host: snail
FLATWORMS
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FLUKES
Flattened leaf shape
Digestive cavity with one opening /mouth at anterior end
Open circulatory system (Gastrovascular cavity)
Flame cells for excreting nitrogen waste
and excess water
Cephalization -Cerebral ganglia with 2 nerve cords
Hermaphrodites with sexual reproduction
NO Eyes
Parasitic with 2 suckers (anterior & ventral) for
attaching to host
Requires 2 hosts to complete life cycle
TEGUMENT for protection from host immune system
FLATWORMS
(Platyhelminthes)
TAPEWORMS
SCOLEX with hooks and suckers
at anterior end to help worm
attach and hold on
NO DIGESTIVE SYSTEM
No mouth/
Absorbs nutrients through
its tegument
EXCRETORY
Flame cells
NERVOUS
Cephalization
Cerebral ganglia with 2 nerve cords
NO eyes
TEGUMENT protects from host
digestive enzymes and immune system
TAPEWORMS
REPRODUCTIVE
• Hermaphroditescan fertilize self or trade
sperm with other worms
• Grow by adding
PROGLOTTIDS
which contain both male
and female reproductive
organs
30 foot worm can
have 2000 proglottids
REPRODUCTION
COMPLICATED LIFE CYCLES
need 2 hosts to complete life cycle
EX: BEEF TAPEWORM
Adults feed and reproduce in humans
larva make cysts in cow
HOW DO THEY INFECT
HUMANS?
Primary host:
Human
Intermediate
host:
cow
FLATWORMS
TAPEWORMS
• NO digestive system/nutrients absorbed
through tegument
• Flame cells for excreting nitrogen waste and excess water
• Cerebral ganglia with 2 nerve cords
• Parasitic with hooks & suckers (scolex) for attachment in
host
• Tegument for protection from host immune system and
digestive juices
• Hermaphrodites with sexual reproduction
Use PROGLOTTIDS to reproduce
• No Eyes