Question

Select the correct statements with reference to Pheretima(excretory system):-
A)Nephridia help in excretion and osmoregulation.
B) Septal nephridia collect the wastes from coelomic fluid with the help of nephrestomes
C) Integumentary nephridia discharge waste materials to the outer body surface through the nephridiopores.
D) Septal nephridia and pharyngeal nephridia discharge wastes into the lumen of gut.

• A. A,B,C
• B. B,C,D
• C. A,C,D
• D. A,B,C,D

Answer 1

Answer: (D)

A,B,C,D

Pheretima is a genus of earthworms found mostly in New Guinea and parts of Southeast Asia. The excreted waste substances are removed out from the body with feces.

The nephridia, besides excretory, are also osmoregulatory in function. The nephridia helps in conserving water by reabsorption from the excreted products during summers and winters, so they pass hypertonic urine in relation to blood.

Septal nephridia are present on the intersegmental septum starting from 15th or 16th segment and continue till the last segment. The septal nephridia open and pour their contents into a pair of supraintestinal excretory duct. These longitudinal excretory ducts open into the lumen of the intestine.

Pharyngeal nephridia discharge waste into the lumen of buccal cavity and pharynx.

Integumentary nephridia opens out independently through nephridiopores on the outer surface of the body wall and are also known as exonephric nephridia.

So the correct answer is option D.