1. Phylum Porifera: Sponges Biology 11

2. Characteristics • Name means “pore bearers”- body has many pores in it • Sessile • Multicellular • Mostly marine (only 100/9000 are freshwater)

3. Structure • Asymmetrical body shape • Made of 2 cells layers • Ectoderm • Endoderm • No specialized tissue or organ systems • Individual cells sense and react to environmental changes

4. Specialized Cells • Do have specialized cells that fulfill the sponge’s life functions • Epidermal cells • Pore cells • Collar cells • Amoebocytes

5. Epidermal cells form outer covering • Water is drawn in through pore cells into a central cavity

6. The collar cells have flagella that beat to create a current to make sure water is being drawn in through pore cells • Water flows out of sponges through a larger opening called the osculum

8. Amoebocytes • Make spicules • Needle-like structures that provide structural support • Made of silica or calcium carbonate • Some made of spongin protein (softer skeleton) • Carry nutrients to other cells • Aid in reproduction

9. Collar Cell • Contain a flagellum to move water in • Brings oxygen and food particles into body of sponge

11. Movement of Water • Water acts as the circulatory, respiratory, reproductive, and excretory systems • Brings in food, oxygen, carries away waste, gametes, larvae • Oxygen is brought in and carbon dioxide and other metabolic wastes are given off

12. Life Functions • Feeding and Digestion • No mouth or digestive tract • Are filter feeders- sift food particles from the water • Driven by water flow • Filtered by collar cells • Excretion • Driven by water flow

13. Respiration • Oxygen diffused from surrounding water into cells • Carbon dioxide diffused from cells to surrounding water

14. Movement • Adults sessile: Remain attached, don’t move • Larvae are mobile

15. Reproduction • Sexual • Most are hermaphrodites (produce both egg and sperm)

16. Sperm released out of osculumand swim to another sponge (with the help of currents) • Enter another sponge’s pore cell • Picked up by collar cells • Carried to an egg by amoebocytes • Fertilization occurs • Zygote develops into a flagellated larvae which is mobile (can be dispersed)

17. Why do sessile animals tend to be hermaphroditic? • Increase change of fertilization • They do not fertilize their own eggs with their own sperm

18. Can also reproduce asexually by: • Fragmentation: part of sponge breaks off • Budding: mitotic growth and break off • Gemmules: collection of cells that are enclosed by hard outer covering contain spicules • Form when conditions are unfavourable

19. Ecological Importance • Provides habitat for many other animals • Like snails, shrimp, sea stars, bacteria… • Is a food source for other animals • Provides a symbiotic relationships with bacteria (bacteria provide food and oxygen to sponge and remove wastes)

20. Used as bath sponges • Produce chemicals (to discourage other animals from eating them) that are being used in research for cancer, viruses, and antibiotics