Canal system is the speciality of which phylum?
A) Porifera
B) Coelenterata
C) Echinodermata
D) None of the above

Hint: The members of this phylum are primitive multicellular animals which have cellular level of organization.

Complete answer:
Phylum Porifera members also known as sponged have a water transport or canal system. Water enters through the minute pores of sponges called ostia in the body wall into a central cavity called spongocoel, from where it goes out through the osculum.

Fig. Canal system in phylum Porifera

Additional information:
Canal system is helpful in food gathering, respiratory exchange and removal of waste.
Choanocytes line the spongocoel and the canals.
Mainly, four types of canal systems are found in sponges. They are the ascon type, sycon type, leucon type and rhagon type. Ascon types are with flagellated radial canals, sycon types are with flagellated radial canals, leucon types are with flagellated chambers and rhagon types are with conical shape and broad base.
Examples: Sycon, Spongilla and Euspongia.

So, the correct answer is phylum Porifera.

Note: Choanocytes are the flagellated collar cells which line the spongocoel and canals. The flagella of choanocytes beat to produce a water current, which helps the water to enter into the body.