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Chapter: BIOLOGY (ZOOLOGY) Standard XI first year 11th text book Assignment topics question and answer Explanation Definition

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Earthworm - Digestive System, Feeding

Earthworm - Digestive System, Feeding
The earthworm feeds on decaying organic materials contained in the soil. It takes the soil into its alimentary canal where the organic matter is digested and absorbed. The unwanted soil particles are sent out as worm casts.

Earthworm

 

Phylum - Annelida

Class - Chaetopoda

Order - Oligochaeta

Type - Lampito mauritii

 

Earthworms are nocturnal animals. They lie in the burrows during the day and come out at night for food. Earthworms leave the burrow only during the rainy season when their burrows are flooded with water.

 

Digestive System :

 

The digestive system runs as a straight tube from mouth to anus. The mouth is situated in the first segment. The mouth opens into the buccal cav-itywhich occupies segments 1 and 2. The buccal cavity in turn leads into a thick muscular Pharynx. The pharynx occupies segments 3 and 4 and is sur-rounded by the pharyngeal glands. The oesophagus is a short narrow tube lying in 5th segment. It leads into the gizzard lying in the 6th segment. Its inner surface has a chitinous lining. The intestine is a large tube extending from the gizzard to the anus. The intestine upto the 14th segment is narrow and the remaining part is sacculated. The dorsal wall of the intestine is folded into the cavity as the typhlosole. This fold contains blood vessels. It increases the absorptive area of the intestine. The inner epithelium consits of columnar cells and glandular cells.

 

Feeding :

 

The earthworm feeds on decaying organic materials contained in the soil. It takes the soil into its alimentary canal where the organic matter is digested and absorbed. The unwanted soil particles are sent out as worm casts.


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