Excretion in annelida long question for +3 zoology students

EXCRETION   IN ANNILIDA

- Excretion is defined as the separetion elimation of nitrogenus west from body to out side.

- The organ involve in excretion called as ecretory organ.

- In annelida exretion is brought about by these following organ.

NEPHRIDIA

- These are coild tubules arrenged segmentally drive from ectoderm and projected in the nephridia named as

1. proto-nephridia

2. meta-nrphridia

A. PROTONEPHRIDIA

- These are primitive type of nephridia open to exterior by an opening called nephridiapore.

- Internaly it  blindly open towords coelom and are branched.

- Each branch ends in a tubular cell ,  called solencytes.

- It is a cavity surrounded by cytoplasm mass.

- Flagellum arises from the mass of cytoplasm.

- It is found in alcepa.

B. METANEPHRIDIA

- It has two opening ,one end is open to the coelom by funnel like structure called nephrostome.

- And orther end open to anterior by nephridiapore,found in nereis.

- Nephridium colid tube like structure embedded in mass of cytoplasm.

NEPHRIDIA   IN  METASCOLEX

There are the three types of nephridia present in metascolex               

they are,

a. MEGANEPHRIDIA

- These are large in size.

- These are arrenged from 9^th segment.

- One pair each nephristome leading into a colid tube from which arises a narow tube called septal excretion canal.

b. MICRONEPHRIDIA

- These are small finger like structure.

- These are arrenged from 14^th segment.

- Each tube open into outside by separate nephridiapore.

-They have no nephrostome and they are otherwise called as intergomentary and exonephric nephridia.

c. PHARYNGEAL NEPHRIDIA

- They are paired structure.

- These are arrenged in side of elimentary canal from 15^th segment and open in to osephagus.

- Here nephrostome is absent.

FOREST  OF NEPHRIDIA

- In phenetima-postma micronephridia arrenged lare on. 14,15,16 segment , hence describe as forest of nephridia.

- There fore 3 excrtory organ found in earthworm.

INTEGOMENTARY  NEPHRIDIA

- Present an inner surface of body wall and open outside hence called as exoneohric nephridia.

- These are present in all segment except the 1^st and 2^nd segment.

- They are about 200-300 nephridia in earth.

FUNCTION  OF NEPHRIDIUM

- It eliminated the nitrogenous waste products from out side of body.

- It maintains the water balance of the body.

- It regulates the osmotic relaton between blood and tissue.

      Prof.- Dr ramakant pradhan 

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