Water Canal System in Porifera MCQ - Practice Questions with Answers

The canal system of sponges is made of ostia in body walls, spongocoel and osculum. It is of following three types: 

Asconoid Type: 

• It is the simplest type of canal system.
• The ostia present on the body wall lead to the spongocoel directly. 
• The route of water can be represented as: water from exterior → incurrent pores → spongocoel → osculum → water out. For example, Leucosolenia.

Syconoid Type: 

• In this type, the body wall is folded into finger-like projections called the radial canals. These radial canals open into the spongocoel through apopyles. 
• The incurrent canals made up of ostia are connected to the radial canals through prosopyles. 
• The route of water can be represented as: dermal pores → incurrent canals  → radial canals → internal ostia (apopyles) → spongocoeL → osculum → out. 
• For example, Scypha, Grantia etc.

Leuconoid Type: 

• It is characterised by highly folded thick walls such that the spongocoel is reduced to a large extent. 
• The folds occur in the form of chambers.
• The route of water can be represented as: dermal ostia → incurrent canals → flagellated chambers →  excurrent canals → larger channels → oscula → out. 
• For example, Spongilla.