Question

In Pheretima, the dorsal surface is distinguished from the ventral surface due to the presence of:
A. Dorsal blood vessel
B. Genital Pores
C. Absence of setae
D. Parapodia

Answer 1

Hint: Pheretima posthuma is the scientific name of the earthworm. It is the invertebrate which is reddish brown in colour and belongs to phylum annelida. It has a long, cylindrical, and segmented body. These are known as metameres which are 100-120 in number.

Complete answer:
The ventral surface of the body of the earthworm is distinguished from its dorsal surface due to the presence of genital openings or genital pores. The mouth and prostomium of the earthworm are present on the anterior side. Prostomium serves as the mouth-covering for the earthworm.

The 14-16 segments consist of dark glandular bands known as the clitellum. In the 14th segment of the body of the earthworm, a single female genital pore is present. Nephridiopores which are numerous small pores are present on the body of the earthworm.

A thin non-cellular cuticle covers the body of the earthworm. Below this layer, the epidermis is present. The epidermis is one-layered thick and consists of columnar epithelial cells. These cells contain secretory gland cells.

the earthworm is bisexual creature, that mean a single eaarthworm carry both male amnd female sex organs. male reproductive organ two pair of testes present in 10-11 segment, while female reproductive organs called ovaries which join the female genital pore that open into fourteen segment.

Hence, the correct answer is option (B).

Note: Here it must be noted that the earthworms are known as “the farmers’ friends”. This is because they continuously make burrows in the soil hence mixing the above layers with the lower layers. They make the soil porous. This process of making the soil fertile is known as vermicomposting.