Question

Answer the following:
a. What is the function of nephridia?
b. How many types of nephridia are found in earthworms based on their location?

Answer 1

Hint: Nephridia are organs found in earthworms in pairs and perform the same functions as vertebrate kidneys. Nephridia are basically of two types that are Metanephridia and Protonephridia.

Complete answer:
> Nephridia perform a vital role in the body of the earthworm as they help in removal of the waste products from the body. Metanephridia is an excretory gland which consists of ciliated funnel opening into the cavity of the body which opens to the organism's exterior and helps in removing waste from the body of the organism. These ciliated tubules expel surplus ions, metabolic waste, food, toxins and other useless hormones out of the body by directing them towards funnel-shaped bodies called nephrostomes. Protonephridia are the dead-end tubules and their ends are called flame cells. They function as osmoregulation for the entire body.

> Types of nephridia based on location in the earthworm body are Septal, Integumentary and Pharyngeal. Septal nephridia are present on the both sides of the inter-segmental septa behind the fifteenth segment and they open into the intestine. Integumentary nephridia are present from the third segment to the last segment which opens on the body surface and lie attached to the body wall. Pharyngeal nephridia are present in the form of paired tufts in fourth, fifth and sixth segments.

Note: There are other types of nephridia like Saccate metanephridia which are the exterior glands which function similarly to the metanephridia. These are found in the majority of the arthropods, crustaceans and arachnids.