Sponges

Question 1

Sponges (Phylum Porifera)

Answer 1

Cellular level of organization
Asymmetical with a few radiate.
Blastula stage but no germ layers or gut formation.
Assemblage of cells embedded in extracellular matrix with skeleton of spicules and protein.
Adults all sessile.
Share few characteristics with metazoans.
Phylogenetically grouped
Body is efficient aquatic filter
Approximately 15,000 species of sponges 
Most are marine
Few live in brackish water, 
150 in fresh water

Question 2

Body Forms

Answer 2

Not an evolutionary sequences (Asconoid to Eluconoid). Independent evolution.
Aconoid
smaller
Chaenocytes: line the spongaeum
Increase in efficiency of water pump and filter