1. Virtual Earthworm Dissection
Images Courtesy of:

2. External Anatomy
The top of the earthworm is the dorsal side. This is the darker side of the worm.
The bottom of the earthworm is the ventral side. This is the lighter side of the worm.
The anterior region of the earthworm is the head region. There is a mouth at the head region.
The posterior region of the earthworm is the tail region. There is an anus at the tail region.

3. External Anatomy: Clitellum
Note the swelling of the earthworm near its anterior side. This is the clitellum.
Each segment of a worm has small pairs of bristles called setae which help it move.

4. Digestive System: Mouth
Mouth: tiny opening at anterior end through which food enters

5. Digestive System: Pharynx
Pharynx: “throat”; smooth part following the mouth

6. Digestive System: Esophagus
Esophagus: main food tube connecting pharynx to crop

7. Digestive System: Crop
Crop: temporary holding tank controls food entering gizzard

8. Digestive System: Gizzard
Gizzard: grinder

9. Digestive System: Intestine
Intestine: absorbs nutrients (food) and water

10. Virtual Animation of Worm Digestion
The animation on worm digestion is courtesy of North Carolina State University. HERMAN THE WORM.

11. Circulatory System: Aortic Arches
Aortic Arches (Hearts):
5 of them pump blood

12. Circulatory System: Dorsal Blood Vessel
Dorsal Blood Vessel: main blood vessel through which blood travels

13. Reproductive System: Seminal Vesicles
Seminal Vesicles: produce sperm (large white organs)

14. Reproductive System: Seminal Receptacles
Seminal Receptacles: store sperm (smaller white organs)

15. Nervous System: Ventral Nerve Cord
Ventral Nerve Cord: sense stimuli (small white cord under intestine)

16. Cuticle
Cuticle: outer protective covering

17. Septum
Septum: individual segment divisions that hold the skin onto the worm

18. Internal View: How many parts can you name?

19. Labeling Diagrams
Match the letter appearing in front of each word in the word bank with the number of the structure.
a. Mouth
b. Pharynx
c. Esophagus
d. Crop
e. Gizzard
f. Intestine
g. Aortic Arches (Hearts)
h. Dorsal Blood Vessel
i. Ventral Blood Vessel
j. Clitellum
k. Seminal Vesicles
l. Seminal Receptacles
m. Ventral Nerve Cord
n. Brain 7 3 2 4 6 5 1 8 9 14 12 11 10 13

20. Labeling Diagrams
Match the letter appearing in front of each word in the word bank with the number of the structure.
a. Mouth
b. Pharynx
c. Esophagus
d. Crop
e. Gizzard
f. Intestine
g. Aortic Arches (Hearts)
h. Dorsal Blood Vessel
i. Ventral Blood Vessel
j. Clitellum
k. Seminal Vesicles
l. Seminal Receptacles
m. Ventral Nerve Cord
n. Brain
7 h
3 c
2 n
4 g
6 f
5 k
1 a
8 j
9 i
14 b
12 d
11 e
10 m
13l