One very special feature in the earthworm Pheretima is that :
- The S-shaped setae embedded in the integument are the defensive weapons used against the enemies
- It has a long dorsal tubular heart
- The typhlosole greatly increases the effective absorption area of the digested food in the intestine
- Fertilisation of eggs occurs inside the body
Answer
(3) The typhlosole greatly increases the effective absorption area of the digested food in the intestine
Solution
As per NCERT, in Pheretima the intestine has a characteristic internal median fold of the dorsal wall called typhlosole (from the 26th segment onwards), which increases the effective area of absorption in the intestine.
⇒ The S-shaped setae help in locomotion, not in defence.
⇒ It has a closed blood vascular system with hearts (paired), not a long dorsal tubular heart (seen in cockroach).
⇒ Fertilisation and development occur within the cocoon, outside the body.
Answer: (3)