1. Invertebrates- Phylum Porifera
Kingdom Animalia
Invertebrates- Phylum Porifera

2. Sponge Structure Bodies completely lack symmetry (asymmetrical)
Masses of specialized cells embedded in gel-like substance of body wall called mesohyl
Totipotent- The plasticity of sponge cells and how specialized types can change into others
Not organized into tissues nor organs (Parazoa)
Body wall covered in tiny pores, ostia, water enters
Larger openings, oscula, water exits
Sessile- Do not move
Attach to surface early in life
Can produce toxins as defense

3. Sponges Pinacoderm- Outer layer of cells of a sponge
Pinacocytes- Thin, flat cells on the outer-surface
Can be tube-like and contractile (porocytes)
Bag-shaped with large internal cavity (Spongocoel)
Lined by choanocytes, or collar cells (Choanoderm collectively)
Flagellated cells draw in water through pores
Amoeboids (Mesenchyme cells)- Irregularly shaped sponge cells
Float in mesohyl to supply nutrients and carry away waste for other cells

4. Structure of a Sponge

5. Protistan Ancestors
Choanocytes closely resemble a protist called a choanoflagellate

6. Feeding Habits of a Sponge
Collar cells function as sieves
Trap plankton and other tiny organisms in the small hair-like projections
Pulls organisms in and digests them intracellularly (within the cell)
Release nutrients and waste into mesohyl
Amoebocytes pick up nutrients from mesohyl and supplies to rest of cells

7. Sponge Skeleton
Skeletal support is to prevent sponge from collapsing in on itself
Not a fixed skeleton, parts found throughout mesohyl
Most sponges composed of spicules
Tiny needles composed of silica or calcium carbonate
Used for protestion as well
Sclerocyte- Cells that produce spicules
Microscleres- Smaller spicules
Macroscleres- Larger spicules
Few composed of spongin (ex: bath sponges)
Resilient, flexible protein fibers
Some contain both

8. Three Types of Sponges Based on skeleton type
Class Calcarea- Calcareous sponges
Spicules composed of calcium carbonate
Class Hexactinellida- Glass sponges- Found in the deepest parts of the ocean
Spicules made of silica
Hexaxon- Unique six-pointed spicule
- Class Demospongiae- Demosponges
Also contain spongin (proteinaceous)

9. Three Body Forms
Ascon- Vase-like Porocytes (ostia) lead directly to spongocoel
Sycon- sponge wall is folded.
incurrent canals -water enters from dermal pores
radial canals (lined with choanocytes)- lead to spongocoel
Leucon- Branched canal system lacking spongocoel
Incurrent canals lead to choanocyte- lined chambers (water slows through these)
Multiple oscula from excurrent canals

10. Reproduction Asexual reproduction:
Regeneration- Cut pieces will grow back
Budding- Shed fragments constantly to make new individuals
Gemmules- Amoebocytes encased in protective coat
Develop when living conditions become to harsh to survive
Sealed in with food to survive
Cells grow into new sponge when conditions

11. Reproduction Sexual reproduction
Most sponges are hermaphrodites (produce both eggs and sperm
Do not self fertilize
Sperm cells of one sponge enter another through pores
Collar cells pass sperm into mesohyl where eggs are located and fertilization occurs
Zygotes develop into larvae and leave the sponge
Inversion- movement of flagellar cells of developing larvae to the outside
Blastula- Hollow larval stage (coeloblastula)
Parenchymula- Solid larval stage
Macromeres- Large cells that form the outer choanoderm
After a brief free-swimming stage they attach to a surface to live as sessile sponges

12. Sexual Reproduction of Sponges