1. Phylum
Porifera

2. Characteristics of Phylum Porifera
Cellular level of organization, without true tissues
Adults exhibit radial symmetry or are asymmetrical
Possess totipotent cells
Possess unique flagellated cells – choanocytes – that create water flow through a water current system
Outer and inner cell layers lack a basement membrane
Outer and inner cell layers divided by a noncellular layer – the mesohyl – that contains some cells and skeletal material
Body support (“skeleton”) provided by spicules composed of calcium carbonate or silicon, a proteinaceous matrix (spongin), or a combination

5. Amoebocytes
Phagocytic – role in digestion
Archeocytes – totipotent
Sclerocytes – spicule production
Spongocytes – spongin
Collenocytes – collagen of mesohyl

6. Choanocytes
feeding
reproduction

11. Based on body form and skeleton type Subphylum (sP) Cellularia
Classification
Based on body form and skeleton type
Subphylum (sP) Cellularia
Class Calcarea
All three body forms
Calcareous spicules
Class Demospongiae
Leuconoid
Siliceous spicules, spongin, or both
80 – 90% of described species

12. Classification Subphylum Symplasma Class Hexactinellida
Siliceous spicules (fused)
Syncytial tissues

16. Physiology
Dependent on flow of water through the body
Brings in food, oxygen, sperm
Out – waste materials
Stop beating of flagella
Not coordinated, local
myocytes – Demospongiae osculum

18. Reproduction Hermaphroditic Some dieocious
Eggs – archeocytes or choanocytes
Sperm – Choanocytes
Sperm released →

22. Read Chapter on Introduction to Eumetazoa