Worms
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Transcript of Worms
Worms
Flatworms, Roundworms, and Segmented Worms
Science7
Characteristics of Worms
All worms share the following characteristics: 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
Ectoderm Mesoderm Endoderm
3 Major Phyla of Worms
There are 3 major phyla of worms:
Platyhelminthes = Flatworms
Nematoda = Roundworms
Annelida = Segmented Worms
Flatworms
From 2 Greek words: Platy means “flat” Helminthe means “worm”
Simplest of all worms Flattened bodies Most are parasites and get food from host
Flatworms: 3 Types
There are many kinds of flatworms: Planarians Tapeworms Flukes
Flatworms: Tapeworms
Tapeworms 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
PlanariansScavengers
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
Flukes Usually live in the
human liver Shape: Oval and
flat Size: 2mm -15 cm
Activity: Draw A Flatworm
Draw, color, and label the diagram of this flatworm in your guided notes.
Digestive Tract(red)
Roundworms
General Characteristics: Cylindrical bodies Contains a digestive system
Food enters at a mouth Waste exits through the anus
Roundworms: Trichinella
Trichinella Lives in muscular tissue of
pigs These worms reproduce in
the intestine of the host 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
Hookworms Enter the body by burrowing
through the soles of feet Eventually ends up in the
intestines where they live off of blood
Roundworms: Pinworms
Pinworms Small white parasitic worms found in the
feces of babies Babies sometimes ingest microscopic eggs
from the soil
Activity: Draw A Roundworm 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
Worms have many unique characteristics different from sponges and cnidarians.
Watch this clip: “Three Phyla of Worms_5min
45 sec”
Listen for the characteristics that worms were the first to have!
Segmented Worms
Characteristics 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
Closed Circulatory System Blood moves within a confined set of blood
vessels Five hearts are located in segments 5-13
Segemented Worms: Earthworms
How they live 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
Earthworms and Soil 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
Draw, color, and label this diagram of a segmented worm in your guided notes.
Gizzard
Crop
Digestive Tract (System) starts in MouthPharynx - throatEsophagus – connects throat to cropCrop – storageGizzard – grindsIntestine – absorbs nutrientsAnus
Pharynx
Esophagus
(setae)
Color Key for Organ Systems Digestive SystemCirculatory SystemNervous SystemReproductive SystemExcretory System
Leeches are Segmented Worms
NOVA Clip_ Leeches_11min!Leeches can be very helpful worms!Fill out your Ticket Slip as you are viewing.