Chapter 4

Question 1

Phylum Porifera Defining characteristic

Answer 1

Microvillar collars surround flagella, with units arising from either single cells or syncytia

Question 2

Collar cell functions in sponges

Answer 2

1. Generate currents that help maintain circulation of seawater within and through the sponge
2. They capture small food particles
3. They capture incoming sperm for fertilization

Question 3

Archaeocytes responsibilities

Answer 3

1. Digesting food particles captured by choanocytes
2. Some may store digested food material
3. May give rise to both sperm and eggs
4. May play an active role in non-self-recognition reactions in response to contact with other sponges
5. Eliminate waste and can specialize to secrete the supporting elements located in the mesohyl layer

Question 4

The three basic levels of sponge construction

Answer 4

1. Asconoid
2. Syconoid
3. Leuconoid