Which one of the following statements about all the four of Spongilla, leech, dolphin and penguin is correct? (a) Penguin is homoiothermic while the remaining three are poikilothermic. (b) Leech is a fresh water form while all others are marine. (c) Spongilla has special collared cells called choanocytes, not found in the remaining three. (d) All are bilaterally symmetrical.
Option C Spongilla is a common, widely distributed fresh water sponge belonging to phylum porifera. Canal system in Spongilla is essentially of rhagon type with choanocytes restricted to small rounded chambers. It is not found in leech, dolphin and penguin.
