1. CNIDARIANS

2. What makes Cnidarians Unique? Cnidarians are group of animals that are very diverse from stony coral to jellyfish. What common thread keeps this phyla of animals together?

3. Common Thread Cniadarians are DIPLOBLASTIC (2 Layers – epidermis and gastrodermis) TRUE TISSUES(muscular, nervous, gastric) CNIDAE (stinging tentacles)

4. Diploblastic Body The two tissue layers are the epidermis and the gastrodermis Mesoglea- Jelly like portion between that separates the two layers.

5. True Tissues True tissues: muscular, nervous, gastric

6. Cnidae Cnidocytes used in defense, feeding, and attachment Some Cnidocytes can produce Nematocysts or stinging cells

7. Nematocysts Food gathering and defense. Long tube with spines that penetrates prey delivering toxin

8. Nematocysts

9. Two Body Forms Polyp: tentacle up (anenomes, coral, hydra) Medusa: tentacle down (jellyfish)

10. Polyp Stage Sessile, Asexual Reproduction, usually attached to substrate, some “walk”

11. Polyp Stage Budding Fission

12. Polyp Stage Polymorphism in polyps

13. Medusa Stage Dioecious, free swimming, sexual reproduction Develop reproductive organs (testis and ovaries)

14. Reproduction Sexual and Asexual reproduction Alternation of generations

15. Reproduction (sexual) Egg and Sperm released from GVC Once combined egg + sperm will form a planula (free swimming larva) Once GVC devolops forms a Polyp

16. Reproduction (asexual) Budding Fission

17. Alteration of Generations 2 Stages: Polyp & Medusa (dimorphic) Polyp Stage – some species asexual reproduction by budding, usually sessile

18. Nutrition Gastrovascular Cavity: Functions in digestion, the exchange of respiratory gases, metabolic waste, and release of gametes

19. Nutrition Feeding: Prey mostly small crustaceans (copepods) Nematocysts paralyze prey, contractile cells move prey to mouth, GVC releases enzymes

20. Skeletal System Hydrostatic – fluid filled body (mesoglea) Epitheliomuscular cells (longitudinal and circular)

21. Nervous System Nerve Net – Nervous system is spread throughout entire body Most primitive nervous system Some sensory structures – ocelli sense light

22. Circulation, excretion, respiration No special structures or tissues, these life functions are carried out directly with the environment

23. Hydrozoa Alteration of generation Mostly Marine (although a few freshwater) Hydra Obelia Physalia

24. Scyphozoa True Jellyfish Mostly found in Medusa stage Some harmful some not to humans Ocelli (rhodopalia) allow for Phototaxis (move toward light)

25. Cubozoa Box Jelly Fish Some possess dangerous nematocysts Active swimmers and feeders Tentacles on corners of medussa

26. Anthozoa Corals & Anemones Lack medusa stage

27. Anemones Can move slowly over some surfaces Live as individuals but in colonies Feed on fish and crustaceans or organic debris

28. Corals Secrete a calcium skeleton Stony coral, large polyped stony corals, and soft corals May use symbiotic algae called zooxanthelle for autotrophism. Can live individually or in groups.

29. Zooxanthelle Symbiotic Algae that provides food for the coral Found in reef- building coral

30. Soft Coral No hard calcium skeleton (although may contain fragments inside them)

31. Large Polyped Stony Coral (Octocoral) Have both soft tissue as well as produces a hard calcium skeleton

32. Stony Corals Little soft tissue mainly hard calcium skeleton

33. Reef building Corals can grow on one another to create entire reef systems

34. Issues Affecting Reefs Many Reef Ecosystems are in peril from being destroyed. There are many culprits aiding in destruction of the reefs.