1. Worms
Chapter 1 Section 4

2. What Worms have in Common
What are the 3 major phyla of worms we are discussing?
Flatworms
Roundworms
Segmented worms

3. Flatworm

4. Flatworms

5. Flatworm http://www.daviddarling.info/images/flatworm_section.jpg

6. Roundworm

7. Segmented Worms

8. Segmented Worms

9. Segmented Worms

10. What Worms have in Common
Which phylum do flatworms belong to?
Platyhelminthes
Which phylum do roundworms belong to?
Nematoda
Which phylum do segmented worms belong to?
Annelida

11. What Worms have in Common
Invertebrates
Long, narrow bodies without legs
Have tissues, organs, and organ systems
Bilateral symmetry
Head and tail end

12. Worms Do worms have a brain? Yes Simplest organism with a brain
Knot of nerve tissue located in the head end
Detect food, mates, and predators quickly
Responds to the information from the brain

13. Reproduction How do worms reproduce? Regeneration : Sexually
Male and female worms = sexually
Have both sex organs – 2 worms mate and exchange sperm
Break into pieces – asexually
Earthworms can’t do this
Regeneration :
Ability to regrow body parts

14. Flatworms Flat bodies Examples: Bodies soft like jelly
Planarians
Flukes
Tapeworms
Bodies soft like jelly
Almost too small to be seen except tapeworms can grow to 12 meters

15. Flatworms Most are parasites that obtain food from their hosts
Organism that lives inside or on another organism
Host:
The organism that a parasite lives on or in
The parasite takes nutrients from the host

16. Tapeworms 1 kind of parasitic flatworm
Absorbs food from the host’s digestive system
Most live in more than 1 host during their lifetime

17. Planarian Nonparasitic flatworm
Glide over rocks, damp soil, and swim slowly through oceans
Scavengers:
Feed on dead or decaying material

18. Planarian
They also are predators towards animals smaller than they are
Have eyespots
Function sort of like eyes but can not see specific images
Head has cells to pick up odors
Use smell to locate food

19. Planarian Feeds like a vacuum cleaner Sucks up partly digested food
Inserts a feeding tube into its food
Sucks up partly digested food
Distributed to body cells by diffusion
Only have 1 opening
Undigested food leaves through the feeding tube

20. Roundworms Million roundworms live in each square meter of sand
Live in moist environment
Tiny and hard to see
May be the most abundant animal on Earth

21. Roundworms Cylindrical body
Tiny strands of spaghetti
Can be carnivores, herbivores, or parasites
Hookworms are a roundworm parasite

22. Hookworm

23. Roundworms Have a digestive system that is open at both ends
Waste exits through the anus
Having a one-way digestive system allows the worm to use its food efficiently and absorb more nutrients

24. Segmented Worms You can find them in your own backyard
Leeches are parasitic segmented worms
More closely related to crabs and snails

25. Segmented Worms Occupy nearly all environments
Use burrows to hide from predators
Sit-and-wait predators

26. Segmentation
Bodies are made up on many linked sections called ___________
Segments
Earthworms usually have more than 100 segments
Some organs are repeated in most segments

27. Segmentation Ex: 1 way digestive tract which means they have an anus
Each segment has tubes that remove wastes
Reproductive organs are found in only certain segments
Nerve cords and the digestive tube run the whole length of the body
1 way digestive tract which means they have an anus

28. Closed Circulatory System
Blood moves only within a connected network of tubes called blood vessels
In an open system the blood leaves the circulatory system and sloshes inside the body
A closed system can move the blood faster

29. Closed Circulatory System
If you have a closed system you can be larger and more active
Blood carries oxygen and food to cells

30. Earthworms Earthworms scavenge for
Dead and decaying plant and animal remains in the soil
When it is damp they come out of their burrows
They only come out when it is damp because their skin can’t dry out

31. Earthworms
They mainly come out at night because they are safer from predators
Obtain oxygen through the moisture on their skin
Bristles on the segments help the worms move

33. Earthworms Benefit us: Make the soil more fertile with their droppings
Loosen soil when they tunnel
Allow air, water, and roots to move through the soil when they tunnel