Worms
Flatworms, Roundworms,
and Segmented Worms
Science7
Characteristics of Worms
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All worms share the following characteristics:
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Invertebrates
Long narrow bodies without legs
Tissues, organs, and organ systems (with brain)
Bilateral Symmetry (head and tail ends)
Reproduction: Sexual and Asexual
3 Cell Layers
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Ectoderm
Mesoderm
Endoderm
3 Major Phyla of Worms
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There are 3 major phyla of worms:
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Platyhelminthes = Flatworms
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Nematoda = Roundworms
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Annelida = Segmented Worms
Flatworms
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From 2 Greek words:
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Platy means “flat”
Helminthe means “worm”
Simplest of all worms
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Flattened bodies
Most are parasites and get food from host
Flatworms: 3 Types
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There are many kinds of flatworms:
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Planarians
Tapeworms
Flukes
Flatworms: Tapeworms
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Tapeworms
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Lives in the intestines of animals (including
humans!)
Uses hooks and suckers on its head to dig into
the lining of an organism’s digestive tract
Considered Parasitic
 Blocks the host’s intestines
 Steals valuable food and water
Can grow 10-12 meters in length
Life Cycle of A Tapeworm
Flatworms: Planarians
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Planarians
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Scavengers
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A feeding tube releases digestive juices to
break down food.
 THINK! – What type of digestion is this?
Odor cells are found on the head
 THINK! – What do the odor cells help with?
Planarians have 2 photosynthetic eyespots
 THINK! – What do the eyespots detect?
Watch Planarians :55
Flatworms: Flukes
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Flukes
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Usually live in the
human liver
Shape: Oval and flat
Size: 2mm -15 cm
Activity: Draw A Flatworm
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Draw, color, and label the diagram of this flatworm in your guided notes.
Digestive Tract
(red)
Roundworms
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General Characteristics:
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Cylindrical bodies
Contains a digestive system
 Food enters at a mouth
 Waste exits through the anus
Roundworms: Trichinella
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Trichinella
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Lives in muscular tissue of pigs
These worms reproduce in the
intestine of the host
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Female worms release hundreds of
immature worms carried in the
bloodstream
These immature worms burrow in
the surrounding tissue causing
pain to the host
Roundworms: Hookworms
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Hookworms
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Enter the body by burrowing
through the soles of feet
Eventually ends up in the
intestines where they live off of
blood
Roundworms: Pinworms
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Pinworms
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Small white parasitic worms found in the feces
of babies
Babies sometimes ingest microscopic eggs from
the soil
Activity: Draw A Roundworm
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Draw, label, and color this diagram of a roundworm in your guided notes.
Compare it to a cnidarian which we just learned about.
New Guinea Worm: Life Cycle
http://www.dhpe.org/infect/guinea.html
New Guinea Worm Emerging
Video Clip
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Worms have many unique characteristics
different from sponges and cnidarians.
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Watch this clip: “Three Phyla of Worms_5min
45 sec”
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Listen for the characteristics that worms were
the first to have!
Segmented Worms
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Characteristics
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Annelida is Latin for “Little Rings”
Body is made of many segments
 An earthworm has more than 100 segments!
 Organs are found within the segments
Segmented Worms: Closed Circulatory System
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Closed Circulatory System
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Blood moves within a confined set of blood vessels
Five hearts are located in segments 5-13
Segemented Worms: Earthworms
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How they live
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They tunnel for a living
They are scavengers eating
dead plant and animal
remains
They crawl by using stiff
bristles (setae) to pull
themselves along
Segmented Worms: Earthworms
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Earthworms and Soil
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Earthworms make soil more fertile
Their tunnels help loosen the soil and allow air, water,
and plant roots to move through it.
Activity: Draw a Segmented Worm
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Draw, color, and label this diagram of a segmented worm in your guided
notes.
Gizzard
Crop
(setae)
Pharynx
Esophagus
Color Key for Organ Systems
Digestive System
Circulatory System
Nervous System
Reproductive System
Excretory System
Digestive Tract (System) starts in Mouth
Pharynx - throat
Esophagus – connects throat to crop
Crop – storage
Gizzard – grinds
Intestine – absorbs nutrients
Anus
Leeches are Segmented Worms
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NOVA Clip_ Leeches_11min!
Leeches can be very helpful worms!
 Fill out your Ticket Slip as you are viewing.
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