Q. Which one of the following exhibits concentric ‘tube within tube’ plan?
A) Cbidaria
B) Annelida
C) Platyhelminthes
D) Nematode
Explanation
In annelids, alimentary canal is straight with anterior mouth and posterior anus. Due to spacious, fluid filled body cavity between body wall and alimentary canal, the body appears like a tube within a tube in section.
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.