METHOD: EARTHWORM (OLIGOCHAETA) DISSECTION
We started by taking our earthworm, placing it in the dissection tray, and identifying the dorsal and ventral sides. The dorsal side is usually more rounded, while the ventral side is flat. We turned our worm with its ventral side up and examined the external parts, such as the setae bristles and the clitellum, using a magnifying glass. Next, we used a scalpel to make an incision on its dorsal side from the head to the clitellum, and pinned the body walls open. Then we looked at the internal parts, the first being the five aortic arches, which are the five small tan bean shaped structures shown in photo 1. These function as the hearts. We also located the dorsal blood vessel, which is the long brown tube running down the whole worm. The pharynx, esophagus, crop, gizzard, and intestine were also examined. After removing the dorsal blood vessel, we could view the ventral nerve cord and the ganglion, as shown in photo 2. We discovered the nephridia were located on the right side of our worm- there is two in every segment. After drawing a quick sketch of our worm, shown to the right, we disposed of the parts and cleaned all tools and our work area. |
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