If a needle is pricked into a living earthworm on its outer surface without damaging the gut,the fluid that comes out is ....

Describe the circulatory system of an earthworm.

The brown color of the earthworm's body is due to the presence of . . . . . . .

Which animal has red blood but lacks red blood cells (erythrocytes)?

Following are the statements about the prostomium of an earthworm.
$(a)$ It serves as a covering for the mouth.
$(b)$ It helps to open cracks in the soil into which it can crawl.
$(c)$ It is one of the sensory structures.
$(d)$ It is the first body segment.
Choose the correct answer from the options given below.

$Pheretima$ $posthuma$ is very useful as: