Organ and Organ Systems in Animals — Bio Zoology STD 11 — Question
Tamilnadu BoardEnglish MediumSTD 11Bio ZoologyOrgan and Organ Systems in Animals5 Marks
Question
Explain the morphology of earthworm, Lampito mauritii.
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Answer
Lampilo mauritii has a long and cylindrical narrow body which is laterally symmetrical.
it is light brown in colour with purplish length at the anterior end.
The body is divided into 165 – 190 segments.
The dorsal surface of the body is marked by a dark mid dorsal line along the longitudinal axis of the body.
The ventral surface has genital opening.
The mouth is found in the centre of the first segment called peristomium. Overhanging
the mouth is a small flag called upper lip or prostomium.
The last segment called pygidiurn has the anus.
The segments 14-17 are swollen with a glandular thickening of the skin called the clitellum.
The body of earthworm is divided into pre clitellar region (1 – 13), clitellar region (14 – 17) and post clitellar region (after 17).
Chitinous body selae are present in all segments except the first, last and clitellar segments. They are locomoting in function.
The dorsal pores are present from the 10th segment onwards. The coelomic fluid
communicates to the exterior through these pores and keeps the body surface moist and free from harmful microorganism.
Between the segment 6/7, 7/8 and 8/9, supernatural openings are present.
The female genital aperture lies on the ventral side in the 14th segment and a pair of male genital apertures are situated determinately in the 1 8th segment.
Nephridiopores are numerous and found throughout the body except a free anterior segments.
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