1. Worms
Flatworms, Roundworms, and Segmented Worms
Science7

2. 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. 3 Major Phyla of Worms There are 3 major phyla of worms:
Platyhelminthes = Flatworms
Nematoda = Roundworms
Annelida = Segmented Worms

4. Flatworms From 2 Greek words: Simplest of all worms Platy means “flat”
Helminthe means “worm”
Simplest of all worms
Flattened bodies
Most are parasites and get food from host

5. Flatworms: 3 Types There are many kinds of flatworms: Planarians
Tapeworms
Flukes

6. 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 meters in length

7. Life Cycle of A Tapeworm

8. Flatworms: Planarians
Scavengers
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?

9. Flatworms: Flukes Flukes Usually live in the human liver
Shape: Oval and flat
Size: 2mm -15 cm

10. Activity: Draw A Flatworm
Draw, color, and label the diagram of this flatworm in your guided notes.
Mouth
Digestive Tract
Muscular Tube for Feeding
Nerve Tissue

11. Roundworms General Characteristics: Cylindrical bodies
Contains a digestive system
Food enters at a mouth
Waste exits through the anus

12. Roundworms: 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

13. Roundworms: Hookworms
Enter the body by burrowing through the soles of feet
Eventually ends up in the intestines where they live off of blood

14. Roundworms: Pinworms Pinworms
Small white parasitic worms found in the feces of babies
Babies sometimes ingest microscopic eggs from the soil

15. 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.

16. 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

17. Segmented Worms: Closed Circulatory System
Blood moves within a confined set of blood vessels
Five hearts are located in segments 5-13

18. 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 to pull themselves along

19. 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.

20. Activity: Draw a Segmented Worm
Draw, color, and label this diagram of a segmented worm in your guided notes.