Transcript Worms and Mollusks

Worms
Mr. D
DO NOW
Write down your homework
 Take out your foldable
 On the back of your foldable answer
this question
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What made scientists put worms in a
different category from cnidarians and
sponges?
Worms
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What are the major classifications of worms?
 Flatworms – Platyhelminthes
Roundworms – Nematoda
 Segmented - Annelida
Name 5 characteristics of all worms.
 Invertebrates, Long narrow bodies without legs, bilateral
symmetry, have tissues, organs, and body systems
How does a worm with both male and female parts usually reproduce?
 Mating – transfer of sperm
How do worms reproduce asexually?
 Can sometimes grow individual worms from pieces
Worms
Sense organs, mouth at
anterior
 Long, slender body allows
rapid movement / control of
direction
 Three phyla
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Flatworms - Platyhelminthes
 Roundworms - Nematoda
 Segmented worms - Annelida
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Characteristics of all worms.
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Inverts
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Bilateral symmetry
Have a brain
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Simplest organisms with a brain
Cells, Tissues, Organs, and Body
Systems
 Long narrow bodies without legs
 Reproduce Sexually and Asexually
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FAT WORMS - Platyhelminthes
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What characteristics do all flatworms share?
 Flat, soft as jelly
What may parasitic flatworms do to their host?
 Lives inside a host and takes food from it.
Give an example of a parasitic flatworm.
 Tapeworm – absorbs food from the host’s digestive system
Give an example of a free-living flatworm.
 Planarian – is free living because it can survive outside its host
How do planaria get food?
 Scavengers – feeding on dead or decaying material. Glides onto its food
and inserts a feeding tube. Digestive juices break down food outside of the
body. Food is sucked up through this tube, and waste also exits this tube.
Phylum Platyhelminthes:
Flatworms
planarian
Thin (few mm thick)
 Bilaterally symmetrical
 Single opening to pass food and waste
 Pharynx extends out to suck in food
 Free-living or parasitic
 Regeneration
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Class Turbellaria: Free-living
flatworms
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Marine / freshwater
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Carnivores or
scavengers
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Light sensitive
eyespots
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Pharynx brings food into gastrovascular cavity
Planarian
Class Trematoda:
Parasitic flatworms
“Flukes”
 Infect internal organs of host
 Some live on outside of host
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Schistosomiasis --Blood fluke
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Affects 200 million people
Schistosoma egg in liver
Schistosomiasis
larvae
Eggs clog blood vessels in
liver, spleen, lungs,
intestines
Intermediate host
Class Cestoda: Tapeworms
Parasitic; flat and long
 Need no digestive system
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scolex
proglottids
Taenia
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Tapeworms can grow to several meters in length in the intestine
Tapeworm life cycle
tapeworm attaches
inside host intestine
larval cysts
zygotes
Roundworms - Nematoda
How are roundworms different from
cnidarians or flatworms
 They have a one-way digestive system that
is tube like with a mouth and an anus.
 Describe the body of a roundworm.
 Small, have a mouth and anus, many have
transparent bodies, round
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Phylum Nematoda:
Roundworms
Free living or parasitic
 Digestive tract has two openings
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Diseasecausing
roundworms:
Trichinella
Transmitted by
consuming
improperly
cooked pork
 Trichinosis
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Disease
caused by
trichnella
Disease-causing
Roundworms:
Elephantiasis
Worm infects
blood and
lymph vessels
 Transmitted
by mosquitoes
 Tropical parts
of Asia
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Swelling caused by blockage of lymph vessels
Disease-causing
Roundworms:
Ascaris
Intestine filled with Ascaris
Parasitic roundworm
 Affects humans, cats, dogs, horses,
pigs, chickens
 Cause severe malnutrition
 Spread by eating food or water
contaminated with Ascaris eggs
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Hook Worms
Enter the body through the skin on the
soles of the feet
 Live in the blood and intestines
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Necator
Hookworms
Hookworms penetrate the bottoms
of bare feet. Do not go barefoot.
This patient presented with a hookworm infection involving the
toes of the right foot, which is also known as “ground itch”.
Usually the first sign of infection is itching, and a rash at the site
where skin touched contaminated soil or sand, which occurs when
the larvae penetrate the skin, followed by anemia, abdominal pain,
diarrhea, loss of appetite, and weight loss..
Pinworm (Enterobius)
0.5 inches long
Guinea Worms
Dracunculus medinensis
Guinea Worms
Segmented Worms - Annelida
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Describe the body of a segmented worm.
 Have a mouth and anus that are separated by
segments
Name 3 characteristics of all segmented worms.
 All have a nerve cord, digestive tube, and a closed
circulatory system.
What is a closed circulatory system
 Blood moves within a closed network of tubes
called vessels.
Phylum Annelida:
Segmented Worms
Body divided into segments by internal walls,
“septa”
 In many annelids, segments specialize for
specific function:
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Eyes
Antennae
Respiration
Example: earthworm
Earthworm
Over 100 segments
 Closed circulatory system
 All fluids contained within small tubes
 Oxygen enters through skin
 Gizzard – grinds dirt and soil
 Setae – bristles that are located on the underside aid
in movement
 Mucus – slippery substance that helps the earthworm
move
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Aerating the soil
Examples to know:
*Phylum Platyhelminthes (flatworms)
Planarian, free living
Tapeworm, parasitic
Flukes: ex. Schistosoma, parasitic, causes Schistosomiasis
*Phylum Nematoda (roundworms)
Trichinella, parasitic, causes trichinosis
filarial worms, parasitic, causes Elephantiasis (filariasis)
Ascaris, parasitic
hookworms, parasitic
pinworms, parasitic
Guinea worms, parasitic
*Phylum Annelida (segmented worms)
earthworm, free living
Nereis, free living
leech
Closing – Crumble and Toss
Get a piece of paper
 How does the structure of the
segmented worm affect its function?
 Planarian?
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Words to know
Scissors ( no scapel), forceps, dissecting
pins
 Anterior – Head end
 Posterior – Butt End
 Ventral – Stomach side (light color)
 Dorsal – Back side ( Dark Blood Vessel)
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Flatworm Lab 3/8/2011
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Please pick up a worm lab and read it
What am I?
Do Now 3/15/2011 TEST 9
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Pick up and Answer Sheet and packet
on the Chair
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After the Test
Kids Survey
 Complete the Packet (on chair)
 Packet Due Thursday
 Remember to Get Frost Valley Activity
Sheets in tomorrow
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