1. Lecture 2 Porifera & Cnidaria

2. Phylum Porifera: The sponges

3. Evolutionary relationships  Why or Porifera considered animals rather than Protists?  How do they differ from other animals (3 ways…)?

5. Sponge structure  Review key parts…  No tissues, organs or body systems!

6. Water movement and feeding [choanocyte, Fig. 33.4]  Role of flagellum  Role of collar  Movement of particles  Phagocytosis

7. Amoebocytes  Move in amoeboid fashion through mesohyle  Secrete spicules and/or spongin  finish digestion  “Garbage-collector cells”  Transport waste to excurrent pore  Can develop into other cell types  Somewhat like stem cells!

8. Protection  Sponges are sessile…  Toxins/warning coloration  Painful or sharp covering (spicules)  Regenerative ability  Camouflage (if not toxic)  Bore into shells.  NOTE: Nudibranch predators co-opt sponge defenses (toxins, spicules)

9. Nudibranch (Phylum Mollusca, Class Gastropoda)

10. Phylum Cnidaria Hydrozoa Scyphozoa Cubozoa Anthozoa

11. Phylum Cnidaria

12. Evolutionary relationships

13. Radiata vs. Bilateria

14. Body organization

15. Key features  Polyps and medusae  Two germ tissue layers (called..?)  Mesoglia  Gastrovascular cavity (functions?)  Nervous system: nerve net  Neurons? Brain? Nerve cords (bundles of axons)?  Tentacles with cnidocytes (stinging cells)

16. Cnidocytes/nematocysts How do they work?

17. Life-history strategies