1. Preparing for an Earthworm Dissection
Preparing for an Earthworm Dissection
Learning the Parts of the Earthworm

2. The arrow points to the worm's clitellum, an organ responsible for mucus production during reproduction.
The dark line shows the location of the dorsal blood vessel. The worm is darker on its upper surface.

3. The arrows point to the earthworm's clitellum, an organ responsible for mucus production during reproduction. The clitellum includes six enlarged segments (32-37).
The arrow points to a swollen area with specialized genital setae (segment 26). During mating, the pair of genital setae are used to help bind two worms together while facing in opposite directions.
The arrow points to one of a pair of sperm grooves, extending from segment 16 to the clitellum. As two worms mate, sperm released at the sperm ducts travels posteriorly in the worm's sperm grooves to reach, and enter, the seminal receptacle opening of the other worm (located opposite its clitellum). The two worms exchange sperm in this manner.
The arrow points to one of a pair of swollen areas on segment 15 containing the openings of the sperm ducts.
The arrow points to segment 14 which contains the openings of the female genital pores. These are only visible when the worm is in reproductive condition.
The arrows point to segment 9 and 10 which contain the four openings of the seminal receptacles. These are only visible when the worm is in reproductive condition.

4. The arrow points to intestine region of the digestive system.
The arrow points to gizzard region of the digestive system. This area of the digestive tube is quite muscular.
The arrow points to crop region of the digestive system. This area of the digestive tube is thin-walled and not very muscular.
The arrows point to two of the worm's six seminal vesicles (located in segments 9-13), storage organs for sperm that the worm has produced.
The arrows point to two of the worm's four seminal receptacles (located in segments 9 and 10), storage organs for sperm received from another worm.
The arrow points to one of the worm's five pairs of aortic arches, located in segments These "hearts" beat and pump blood from the dorsal to the ventral vessel.
The arrow points to esophagus region of the digestive system. This organ extends through the aortic arch region and connects to the crop.
The arrow points to pharynx region of the digestive system. This organ of digestion is quite muscular.
The arrow points to worm's suprapharangeal ganglia or "brain". It loops around the pharynx to form the ventral nerve cord that extends the length of the worm.

5. The arrows point to two of the four seminal receptacles (located in segments 9 and 10), storage organs for sperm received from another worm.
The arrow points to the worm's ventral nerve cord. It extends the length of the animal