Earthworm Research Paper

501 Words 3 Pages
3. The earthworm has a segmented body with a mouth at the anterior end and an anus at the posterior end. It has a smooth, purple dorsal side and a rough, yellow ventral side with setae. Two sperm grooves run along the body from segment 15 (where sperm ducts are also located) to the clitellum, which looks like a tube surrounding the earthworm’s body and is closer to the anterior end.
4. The setae are likely on the outside of the body for more effective locomotion. They allow the earthworm to grasp onto the soil as its muscles contract, moving it forward. The setae’s grip also prevents predators from snatching the earthworm off the ground. If the setae were located on the inside of the body, the earthworm would not be able to anchor itself
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A digestive tract, reproductive organs, and blood vessels could be seen inside the earthworm. The mouth led to a pharynx, esophagus (which was covered by the reproductive organs), a soft crop, hard gizzard, and an intestine that continued on to the rest of the body. The earthworm’s brain was barely visible. A pair of small, white, ball-shaped seminal receptacles lay on each side of the earthworm, along with two pairs of larger, whitish seminal vesicles below them. Beneath the reproductive organs, a dark aortic arch was visible. A gray tube, the dorsal vessel, ran along the earthworm’s back. The coelom was the space around the organs, as it is a body cavity surrounding the organs.
7. The crop, gizzard, and intestine contained soil (food). The gizzard had a much thicker wall than the crop, which reflects their functions. The crop is just used for temporary storage of food; the gizzard, on the other hand, requires a stronger structure to mechanically grind down food.
8. The earthworm demonstrates cephalization because it contains a brain, the cerebral ganglia, concentrated at its anterior end. The cerebral ganglia are connected to the rest of the body by the ventral nerve cord.
9. The nephridia are kidney-shaped structures located on either side of the intestine. Each segment has two nephridia, maybe for faster elimination of wastes as urine through excretory pores as well as the reabsorption of small nutrients and

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