Question

Canal system is a characteristic of
a. Hydra
b. Sycon
c. Adamsia
d. Echinus

Answer 1

Hint: Canal system is a characteristic feature in phylum Porifera. It is also called an aquiferous system. The canal system in Porifera acts as a water circulatory system. It also helps in food acquisition, respiration, and excretion.

Complete answer:
Canal system is a system of interconnected canals of different types inside the body of poriferan animals. It acts as a water circulatory system and also helps in food acquisition, respiration, and excretion of waste materials.

From the given options, Sycon belongs to phylum Porifera and thus has canal system characteristics. Sycon is a genus of calcareous sponges. They have a thick body wall with numerous folds forming a canal system. They are often tube shaped. The canal system in Porifera is of three types:
• Asconoid
• Syconoid
• Leuconoid

Sycons exhibit syconoid canal systems. It is more complex than any other type. It is derived from asconoid type of canal system. It consists of two types of canal incurrent and radial which are parallel and alternating to each other. Incurrent canals are mostly found in non-flagellated sycons and radial is found in flagellated sycons. The radial canal is lined by specialized cells called choanocytes. The spongocoel in sycons is quite narrow and is lined by specialized cells called pinacocytes.

The incoming water enters in Sycon to incurrent canal through dermal ostia. From the incurrent canal the water passes to that radial canal with the help of prosopyles. The water then moves to the spongocoel through apopyles and eventually moves outside through the osculum. Examples of Sycon include Scypha, Grantia, etc.

Hence, the correct answer is option (b).

Note: Canal system has much significance in poriferan animals.
• They carry food for nutrition in them.
• They carry out undigested food out of their body helping in excretion.
• They also help in reproduction of Porifera animals.