Worm dissection

1. I identified the dorsal and ventral side of the worm, placing it on the wax ventral side down, using pins at angles. I looked for the anterior and posterior ends. Each segment of the worm contains nephridiopores.
2. I used a scalpel to make an incision posterior to the clitellum and towards the mouth. I then used scissors to cut down to the mouth and used a seeker and pins to open up the worm.
3. From the mouth, I identified…
the pharynx, the oesophagus, the crop (temporarily stores food), the gizzard (then grinds the food), the intestine (which runs to its anus).
4. I then located the dorsal blood vessel, 5 pairs of the aortic arches, cerebral ganglia, ventral nerve cord , nephridia (excretory organs which remove nitrogenous waste).
Earth worms are hermaphroditic. Eggs are produced in the ovaries (segment 13). Eggs pass through the female genital pores.
Sperm are produced in the testes (Segments 9 to 12). Sperm pass through the male genital pores.
Openings to the oviducts are found at segment 14, these release eggs. Sperm ducts can be found on segment 15. The clitellum is the enlarged structure that begins at segment 31, it secretes mucus to hold earthworms together during mating.


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