Question

In most simple type of canal system of Porifera, water flows through which one of the following ways?

• A. Ostia $\to$ Spongocoel $\to$ Osculum $\to$ Exterior
• B. Spongocoel $\to$ Ostia $\to$ Osculum $\to$ Exterior
• C. Osculum $\to$ Spongocoel $\to$ Ostia $\to$ Exterior
• D. Osculum $\to$ Ostia $\to$ Spongocoel $\to$ Exterior

Answer 1

Answer: (A)

The ascon type is the simplest type of canal system found in asconoid sponges like Leucosolenia. The course of water current in ascon type of canal system looks like $\text{Ingressing}\text{water}\underset{\text{Ostia}}{\overset{\text{Trough}}{\to }}\text{spongocoel}$ $\underset{\text{Osculum}}{\overset{\text{Through}}{\to }}\text{To}\text{outside}$