Body Wall of Earthworm

Question 1

The body wall of earthworm is composed of?

Answer 1

-Cuticle
- Epidermis
- Muscular layer
- Parietal layer

Question 2

Epidermis :

Answer 2

• Thin cellular layer externally covered by elastic membrane called cuticle.
• Consists of four type of cells : supporting cells, glandular cells, sensory cells and basal cells (Columnar type)
• Supporting cells : elongated with oval nuclei at the middle
• Glandular cells are of two types : albumen secreting and mucus secreting cells
• Sensory cells are narrow and elongated a little above the ground, that receives external stimuli and sends it to nervous system
• Basal cells lie at the spaces between gland cells for support.

Question 3

Muscular layer :

Answer 3

• Consists of circular and longitudinal muscles.
• Two additional set of muscles are found in the base of each setal sac, CM and LM.
• Contraction of circular muscles make the body thin and long whereas relaxation make it thick
• Contraction of longitudinal muscles make the body thick and relaxation makes it thick.

Question 4

Parietal layer :

Answer 4

• The innermost layer of body wall, formed by splitting of mesoderm during development due to which it is called parietal layer.
  -Outer boundary of coeloem.

Question 5

Cuticle:

Answer 5

Thin, double layered, non chitinous, elastic and living outermost layer made up of collagen fiber. It protects and also helps in locomotion.