Question

In which one of these, gut expels excretory products?

• A. Man
• B. Frog
• C. Dog
• D. Earthworm

Answer 1

The correct option is D Earthworm

The excretory organs of earthworm are coiled tubular structures, known as nephridia. A nephridium consists of a ciliated nephridial canal, that opens into the coelom by nephrostome and to the exterior or in the gut by nephridiopore. The walls of nephridia are glandular and richly supplied with blood vessels, they extract solutes and water from the blood by ultra filtration, and discharge the filtrate into the nephridial canal.

In the nephridial canal, the useful materials are reabsorbed from filtrate and some waste material are secreted into it. The final urine, so formed is then discharged into the gut from where it comes to the exterior from the opening, called as nephridiopore. Excretion through alimentary canal is an adaptation for water conservation.