Question

Which of the following nephridia is not found in earthworm?
A. Septal nephridia
B. Macro nephridia
C. Integumentary nephridia
D. Pharyngeal nephridia

Answer 1

Hint: A terrestrial invertebrate which belongs to the order opisthopora is called an earthworm. Coiled tubular duct-like organs that regulate the function of filtering and removing waste out of the body is called nephridia. Three types of nephridia are present in earthworm and are named based on the location it is found in the earthworm.

Complete answer: An earthworm is a terrestrial animal whose body plan is like a tube within a tube and externally it shows the presence of segmentation corresponding to the internal segmentation. An organ called nephridia is a tube coiled like structure that performs the function of filtering waste out of the body. They are mainly grouped in pairs and are present throughout the body. Three types of nephridia are seen on the earthworm’s body. Depending upon the location it is situated they are named pharyngeal nephridia, integumentary nephridia, and septal nephridia. Large numbers of smaller nephridia are grouped into three sets of tusks called pharyngeal nephridia. Filtering nitrogen from the clusters of surrounding capillaries is done by pharyngeal nephridia. The nephridia located on both sides of septa are called septal nephridia. Maintenance of water regulation and osmoregulation in earthworm is done by the septal earthworm. Integumentary nephridia are located throughout the body of the earthworm and help in the exchange of nitrogen from the body to the soil.

So, option B is the correct answer.

Note: Nephridia is a part of the excretory system of earthworm. Nephridia is present in all segments of the earthworm but is absent in the starting first segments and last one segment. However, the respiration system in earthworms does not have special organs to perform respiration. Therefore, the exchange of gases takes place through moist skin and capillaries.