2. Sponges Phylum Porifera
The most primitive multi-cellular animals that possess no proper organs
Multicellular animals but do not contain true tissues
Body is covered in pores and canals
Sessile (permanently attached to a surface)

3. Sponges
All aquatic
> 10,000 species: 150 freshwater species, 9,850 marine species
Symmetry: Asymmetrical or radially symmetrical
Classified according to shape (asconoid, syconoid, leuconoid)

4. Asconoid Sponges Shaped like a simple tube perforated by pores
Spongocoel: open, internal part of tube
Osculum: single opening to spongocoel

5. Asconoid Sponges

6. Asconoid Sponges

7. Asconoid Sponges

8. Sponge Anatomy

9. Syconoid Sponges More complex than asconoid sponges Larger in size
Tubular shape with a single osculum
Thicker body wall with longer pore canals
Canals are lined by choanocytes

10. Syconoid Sponges

11. Syconoid Sponges

12. Leuconoid Sponges Largest and most complex sponges
Made up of masses of tissue penetrated by numerous canals
Canals lead to many small chambers lined with flagellated collar cells
Central canal and spongocoel eliminated
Thick body wall with many folds that allow for high surface area and low volume

13. Leuconoid Sponges

14. Leuconoid Sponges

15. Leuconoid Sponges

16. Leuconoid Sponges

17. Sponge Anatomy Skeletons consist of spicules and spongin
Many sponges have a skeleton made up of spicules (spiny strengthening rods made of silica or calcium)
Other sponges have a skeleton made up of spongin (a flexible, fibrous material)
Some sponges have both

19. Sponge Anatomy 3 layers: Epithelial: Outer protective layer
Mesenchyme: Middle jelly-like layer also contains skeletal sponging and spicules
Inner: lined with choanocytes and forms the spongocoel

20. Sponge Anatomy Types of Cells
Amoebocytes: mobile cells found in the mesenchyme
Porocytes: cells that line the pores
Choanocytes AKA collar cells
Specialized cells with a jelly-like collar and a single flagellum
Collar traps plankton
Flagellum creates water current
These cells line the central canal and pores

21. Collar Cell
Flagellum
Collar
Cell body

22. Sponge Anatomy Types of Cells (cont.)
Pinacocyte: cells that form the epithelial layer

24. How Do Sponges Eat?
Large volumes of water pass through a sponge’s body every day (5.3 gallons for a large sponge)
Filter plankton and detritus from water
Particles of food are trapped by jelly-like collar of choanocyte and is phagocytised by cell body
Wastes are excreted into spongocoel and expelled through osculum

26. How Do Sponges “Breathe”?
All cells of a sponge are in continuous contact with water
Water currents created by flagella of collar cells draw oxygenated water into the sponge and force oxygen-poor water out of the osculum
Oxygen diffuses into all body cells

27. Not Much of Anything Sponges don’t have
a nervous system
a circulatory system
muscles
a digestive system
Why? Because they don’t have any organs which are needed to make a “system”…they don’t even have tissues that make up organs!

28. Sponge Reproduction
Only way a sponge species can disperse and colonize new areas
Both sexual and asexual reproduction
Regeneration can also be a means of reproduction

29. Sponge Reproduction Sexual
production and release of large numbers of sperm cells released in clouds
sperm transported to other sponges by water currents
flagellated amphiblastula larvae (free swimming larva)

30. Sponge Reproduction Asexual Budding: Cuttings: (Regeneration)
parent sponge produces gemmules, each of which can develop into a new sponge
bud develops and then breaks off parent, then attaches to the substrate
Cuttings: (Regeneration)
When cut or torn sponges can regenerate to repair itself
If a section is removed entirely it can grow into another sponge

31. Threats and Predators of Sponges
Sedimentation: clog up pores
agricultural practices
deforestation
dredging or other disturbance of water
Parasitism
Aquatic and terrestrial-based pollutants kill or weaken sponges
Reef destruction destroys sponge habitats

32. Threats and Predators of Sponges
Predators of sponges include:
fish
sea slugs
humans (for commercial use, not for food)