Question

What is the primary function of enteronephric nephridia of Pheretima?
A. Osmoregulation
B. Excretion of nitrogenous waste
C. Respiration
D. Locomotion

Answer 1

Hint: Enteronephric nephridia discharge their waste product into the alimentary canal through septal and pharyngeal nephridia. Nephridia are coiled tubular duct-like organs, filter and remove waste from the earthworm’s body. In fewer advanced worms like flatworms, nephridia are not specialized whereas in more advanced segmented worms like earthworms specialized nephridia are groups to perform different functions. .

Complete answer: Pheretima is a genus of earthworms having clitellum which is a brand of glandular tissue present on segments. It is a long, elongated, cylindrical narrow body that is bilaterally symmetrical. Nephridia are coiled tubular duct-like organs, filter and remove waste from the earthworm’s body. A various number of very minute nephridiopores are found situated in the body, these pores are called nephridia which helps to remove the excretory material from the body. In pheretima, the exchange of the gases takes place through which is semi transparent and thin. For locomotion no specialized organs are there, the contraction and relaxation of the muscles help in locomotion. Antennal glands receive the blood filtrate and help in osmoregulation.
So, the correct answer is “Option B”.

Additional Information:
Pheretima is generally nocturnal and can reproduce within a night. Like all earthworms, this pheretima also needs to keep their body moist for respiration. $200$ to $250$ to per segment of integumentary nephridia are distributed throughout the earthworm's body. This tiny nephridium helps the excretion of the nitrogenous waste from the body. Nephridia is the main excretory organ. Based on location, there are three types of nephridia: septal, integumentary, and pharyngeal. Depending on the position, the structure of the nephridia also changes.

Note:
The primary function of the enteronephric pheretima is the excretion of nitrogenous waste. The nephridia are coiled, tubular like organs, filter, and remove waste from earthworm’s body. Thousands of integumentary nephridia are present on the wall of the earthworm. Septal nephridia and pharyngeal nephridia of earthworm are enteronephric and thus excrete nitrogenous waste into the lumen of the alimentary canal.