Answer the following:
How many types of nephridia are found in earthworm based on their location?

(3) On the basis of their location,three types of nephridia are found in earthworms. They are:
$1$. Septal nephridia: These are present on both sides of the inter-segmental septa behind the $15^{\text{th}}$ segment. They open into the intestines.
$2$. Integumentary nephridia: These lie attached to the body wall from the $3^{\text{rd}}$ segment to the last segment,which open on the body surface.
$3$. Pharyngeal nephridia: These are present as three paired tufts in the $4^{\text{th}}$,$5^{\text{th}}$,and $6^{\text{th}}$ segments.