1. Phylum Porifera
The Sponges

2. Characteristics of Sponges
No definite symmetry
Multicellular, few tissues, no organs
No true body cavity (water filled space)
Sessile as adults (live attached to something)
Reproduce sexually or asexually
Have no nervous system
Larval stage planktonic
Live in water
Filter feeders
Often have skeleton of spicules

3. Symmetry
None
Radial
Bilateral

4. General Information Simplest of all animals Over 600 million years old
~ 5000 species, mostly marine
Important reef organisms
3 groups of sponges
Classified based on what spicules are made of and how many rays

5. Classification
Calcarea Sponges: 1, 3, or 4 rayed spicules made of calcium carbonate
Demospongiae Sponges: 1, 2, or 4 rayed spicules made of silica
Hexactinellida Sponges: rayed spicules made of silica (glass sponges)

6. Encrusting sponges cover rocks in a thin layer instead of forming tall tubes

7. Anatomy Body made of single layer of flagellated cells
Canals have openings to outside (ostia)
Water enters sponge through ostia
Exits through osculum
Spongocoel: center canal

8. Choanocytes Canals lined with flagellated cells (choanocytes)
Choanocytes beat flagellum to keep water flowing in correct direction
Trap food
Help larval form swim

9. Body Types
3 Body Types
Asconoid: simplest, single choanocyte-lined canal
Syconoid: canals branched & choanocyte-lined (spongocoel: no choanocytes)
Leuconoid: most complex, many branches, choanocytes only in special chambers

10. Reproduction Most sponges are hermaphrodites (both male and female)
Only one gender at a time
Areas of cells will change into egg or sperm
Sperm released through osculum of “male” sponge
Sperm enters “female” sponge and fertilize eggs
Larvae released, float for a few days, then settles

11. Sponges can also reproduce asexually
Pieces (gemmules) will break off, settle, and develop into a new sponge

12. Feeding Strategies Filter Feeders
Water flowing through ostia carries bacteria and small organic particles
Oxygen also absorbed from water
Waste removed as water flows through

13. Weird But True Carnivorous Sponge discovered deep Antarctic waters
Eats small crustaceans
Spicules act like Velcro
Cells surround prey and dissolve

14. Human Use
Humans collect and dry sea sponges to use in the shower