Q. Which one of the following statements about all the four of Spongilla, Leech, Dolphin and Penguin is correct ?
A) All are bilaterally symmetrical
B) Penguin is homoiothermic while the remaining three are poikilothermic
C) Leech is a fresh water form while all others are marine
D) Spongilla has special collared cells called choanocytes, not found in the remaining three
Explanation
[Solution from source] Collar cells (choanocytes) lining the canal system are unique to sponges such as Spongilla. The homoiothermy statement fails because the dolphin, a mammal, is also warm-blooded. Spongilla is a freshwater sponge and is asymmetrical, so the other two statements fail too. Answer (4).
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.