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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 - Circulatory System

Earthworm - Circulatory System
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.

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.

 

Circulatory System :

 

In the body of earthworm there are two median longitudinal vessels. The dorsal longitudinal vessel runs above the alimentary canal. The ven-tral longitudinal vessel runs below the alimentary canal. The dorsal vessel is contractile and blood flows forwards in it. There are paired valves inside this vessel which prevent the backward flow of the blood. The ventral vessel is non contractile and blood flows backwards in it. The ventral vessel has no valves. In the anterior part of the body the dorsal vessel is connected with the ventral vessel by eight pairs of commissural vessels or the lateral heartslying in the segments 6 to 13. These vessels run on either side of the alimen-tary canal and pump blood from the dorsal vessel to the ventral vessel.

 

 

The dorsal vessel receives blood from various organs in the body. The ventral vessel supplies blood to the various organs.

 

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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