1. WORM DISSECTION

2. KIDSPIRATION by Riedell

3. CLASSIFICATION Kingdom: Phylum: Class: ANIMALIA Annelida
“little rings”
OLIGOCHAETA
“few bristles”

4. SETA (plural: setae) BRISTLES on VENTRAL surface

5. SETAE- Provide traction

6. Segmentation Compartments allow individual parts to move independently
Damage insurance
If one section is damaged, others can still function
BIODIDAC

7. Cartoon by: Gary Larson

8. WHICH END IS WHICH? CLITELLUM = ring Doesn’t go all the way around
Image by Riedell/VanderWal©2005
CLITELLUM = ring
Doesn’t go all the way around
Closest to anterior end
Makes mucous for reproduction

9. 2 opening digestive system
Image by Riedell/VanderWal©2005
Image by Riedell/VanderWal©2005
MOUTH ANUS
Prostomium covers/protects mouth opening senses light/dark, chemicals (food), vibration

10. EXTERNAL STRUCTURES
PROSTOMIUM

11. EXTERNAL STRUCTURES DORSAL BLOOD VESSEL CAMOUFLAGE
DORSAL BLOOD VESSEL
CAMOUFLAGE

12. CUTICLE (non-cellular protective layer)

13. RESPIRATORY No respiratory organs
Skin must stay moist for gas exchange
Glands produce mucous

14. SURVIVING HOT DRY CONDITIONS
Worms tunnel deeper into the soil Roll into a ball Cover themselves with mucous Slow their body functions down
“Suspended animation”
= ESTIVATION
Wait for conditions
to improve

15. SEXUAL REPRODUCTION Earthworms are hermaphrodites
HAVE BOTH MALE & FEMALE
REPRODUCTIVE ORGANS in same worm

16. SEXUAL REPRODUCTION
OVARIES – make eggs
TESTES- make sperm

17. EXTERNAL STRUCTURES MALE GENITAL PORE- releases sperm to give away
EXTERNAL STRUCTURES
MALE GENITAL PORE- releases sperm to give away
FEMALE GENITAL PORE- releases eggs
OPENINGS to SEMINAL RECEPTACLES- receive
sperm from other worms when trade

18. EXTERNAL STRUCTURES
Image by Riedell/VanderWal©2005
SPERM GROOVE- carries sperm from MALE GENITAL PORE down to CLITELLUM

19. SEXUAL REPRODUCTION Earthworms are HERMAPHRODITES
Earthworms are HERMAPHRODITES
BUT. . . DON’T fertilize themselves!

20. SEXUAL REPRODUCTION EXTERNAL FERTILIZATION
Produce COCOONS
made of MUCOUS
and CHITIN
(tough carbohydrate)

21. DIRECT DEVELOPMENT Earthworms produce between 4 - 70 cocoons per year.
Animated images from:
DIRECT DEVELOPMENT
Earthworms produce between
cocoons per year.
Each cocoon may contain
2-20 embryos.
Baby worms hatch after a few weeks

22. LOOK INSIDE

23. COELOM = space around organs
Image by Riedell/Vanderwal ©2005

24. INTERNAL STRUCTURES EUCOELOMATES “true” coelom
EUCOELOMATES
“true” coelom

25. SEPTUM (pl. SEPTA) Dividing walls separate coelom into compartments
Image by Riedell/Vanderwal ©2005
Image from: BIODIDAC

26. SKELETAL “hydrostatic skeleton”
Fluid in coelom protects organs and provides support

27. EXCRETORY SYSTEM Collect & excrete NITROGEN WASTE Osmoregulation
Collect & excrete NITROGEN WASTE
Osmoregulation
NEPHRIDIUM
pl. NEPHRIDIA
EXCRETORY TUBULES

28. INTERNAL STRUCTURES

29. REPRODUCTIVE SYSTEM SEMINAL VESICLES STORE SPERM MADE BY WORM
Image by Riedell/Vanderwal©2005
STORE SPERM MADE BY WORM
TO “GIVE AWAY” TO OTHERS

30. REPRODUCTIVE SYSTEM SEMINAL RECEPTACLES
Image by Riedell/Vanderwal©2005
SEMINAL RECEPTACLES
Store sperm received from other worms
during sex

31. CLOSED circulatory system
DORSAL BLOOD VESSEL
VENTRAL BLOOD VESSEL

32. DORSAL BLOOD VESSEL Images by Riedell/VanderWal©2005
Image by Riedell/Vanderwal ©2005

33. 5 AORTIC ARCHES act as “heart” to pump blood
Image by Riedell/Vanderwal
Image by Riedell/Vanderwal ©2005

34. Image from: http://www.urbanext.uiuc.edu/worms/anatomy/anatomy6.html

35. INTERNAL STRUCTURES

36. PHARYNX PHARYNX Muscular tube pulls in food
Image by Riedell/Vanderwal ©2005
PHARYNX

37. INTERNAL STRUCTURES CROP-stores food waiting to be digested
Image by Riedell/Vanderwal ©2005  
CROP-stores food waiting to be digested
GIZZARD- grind and mash food

38. INTESTINE- absorbs nutrients
Images by Riedell/Vanderwal ©2005
ADAPTATIONS for getting nutrients out of SOIL
1. REALLY LONG INTESTINE so food spends long time passing through
2. TYPHLOSOLE- ridge inside increases surface area for more absorption

39. TYPHLOSOLE Ridge inside intestine
increases surface area so more nutrients are absorbed
TYPHLOSOLE Ridge inside intestine

40. TYPHLOSOLE inside intestine
Image by Riedell/Vanderwal ©2005

41. Earthworms play an important role in soil fertility
"...it may be doubted if there are any other animals which have
played such an important part in the history of the world as these
lowly organized creatures." ~ Charles Darwin
Decompose organic matter
(dead leaves, animal waste, etc)
Return nutrients to soil
Burrowing allows air and water to penetrate to roots
Tunnels loosen soil so roots can grow more easily
“intestines of the earth”
~ Aristotle

42.   UNDERNEATH DIGESTIVE SYSTEM VENTRAL NERVE CORD
Image by: Riedell/Vanderwal © 2005  
UNDERNEATH DIGESTIVE SYSTEM
VENTRAL NERVE CORD
(nerves usually white)
VENTRAL BLOOD VESSEL (usually dark)

43. REMEMBER embryo orientation is flipped
in vertebrates and invertebrates!
 Images modified from:

44. BODY PLANS are also flipped!
Most INVERTEBRATES have a DORSAL HEART & a VENTRAL NERVE CORD
ALL VERTEBRATES have a DORSAL NERVE CORD & a VENTRAL HEART.

45. If in located in head and acting as “brain” = CEREBRAL GANGLIA
GANGLIA= nerve center
If in located in head and acting as “brain”
= CEREBRAL GANGLIA

46. MUSCULAR SYSTEM
Image from:

47. Image from: http://www.urbanext.uiuc.edu/worms/anatomy/anatomy8.html