Question

Question 1. Why do you think choanocyte chambers are so much larger than the other canals in most sponges? Think about how a sponge would benefit from large chambers in terms nutrient and gas exchange, and excreting wastes. Explain your answer.

Question 2. In sponges that live in calm water, flow velocity increases considerably after leaving the choanocyte chamber. Why?

Question 3. Assume that sponge tissue filters 20 L of water per cubic centimeter of sponge tissue a day (as mentioned in the sponge video). How long would it take to a 0.5 m³ sponge to filter 20,000 gallons of water? This is the amount in an average swimming pool.

Answer 1

Question 1: Large choanocyte chambers results in slower flow of water. Slower water flow facilitates increased contact time. With the increased contact time, any exchange between the organism and water occurs more efficiently, meaning that gas and nutritions can be absorbed in more amount and the waste can be excreted more efficiently.

Question 2: When sponges leave the choanocyte chamber, the larger choanocyte chambers are no present. So the area through which the water flows reduces which results in higher velocity of water.

Question 3:

Filteration rate = 20 L/ m³ . Day

Volume of sponge = 0.5 m3

Volume of water = 20000 gallons = 20000 * 3.79 = 75800 L (1 gallon = 3.79 L)

Volume of water filtered in a day by the sponge = Filteration rate * Volume of sponge

= 20*0.5 = 10 L/ Day

Time required to filteration = Volume of water / Volume of water filtered in a day by the sponge

= 75800 / 10 = 7580 Days

ANSWER: 7580 Days