1 Phylum Cnidaria BIO 2215 Oklahoma City Community College Dennis Anderson

2 Phylum Cnidaria Radial symmetry Mouth at oral end surrounded by tentacles. One opening into and out of gastrovascular cavity. Cnidocytes that discharge pneumatocysts Two body forms –Polyp –Medusa Two germ layers Nerve net

3 Radial symmetry

4 Mouth and Tentacles

5 Fig. 13.2

6 Generalized Cnidarian Life Cycle Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

7 Cnidocyte Structure and Nematocyst Discharge Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

8 Diploblastic - 2 germ layers –Epidermis - outer covering (ectoderm) –Mesoglea - middle non-living jelly-like layer –Gastrodermis - lines gastrovascular cavity (endoderm)

9 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Cnidarian Body Wall

10 Nervous System Nerve cells, arranged in a nerve net.

11 Class Hydrozoa Freshwater & marine. Cnidocytes present only on epidermis. Medusa (if present) with a muscular velum. Mesoglea without ameboid cells. Asexual reproduction by budding. Sexual reproduction via gametes produced by epidermis & released into water.

12 Class Hydrozoa Hydra Obelia Gonionemus Physalia

13 Class Hydrozoa HydraSpermariesSpermaries OvariesOvaries EncapsulatedembryoEncapsulatedembryo Sexual cycle Asexual cycle BuddingBudding

14 GastrovascularcavityGastrovascularcavity EpidermisEpidermis MesogleaMesoglea GastrodermisGastrodermis Hydra Body Wall

15 Fig. 13.9

16 Obelia

17 Obelia MedusaeGonangium Medusa bud

18 Class Hydrozoa Gonionemus

19 Class Hydrozoa Gonionemus Velum

20 Class Hydrozoa Physalia

21 Class Scyphozoa Tentacles up to 70 meters in length Cnidocytes present in gastrodermis & epidermis Thick mesoglea contains ameboid cells Gametes produced by gastrodermis All marine

22 Class Scyphozoa Aurelia

23 Aurelia Life History Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

24 Fig

25 Planula Larva Ciliated larva then can swim to a new location

26 Aurelia EggsEggs MesogleaMesoglea GastrovascularcavityGastrovascularcavity MouthMouth

27 Aurelia Mouth Oral arm Gastric pouch Tentacles

28 Class Cubozoa Medusa dominant & cuboid Tentacles arise at four corners from blade-like pendalium. All marine Strong swimmers which prey primarily on fish Stings of some may be fatal within minutes to humans.

29 Class Cubozoa GonadGonad TentacleTentacle PedaliumPedalium

30 Class Cubozoa Chironex Sea Wasp

31 Class Anthozoa Medusa stage absent Solitary or colonial Some produce protective skeletons Gastrovascular cavity subdivided by at least 8 mesenteries Cnidocytes on mesenteries Mesoglea contains ameboid cells All Marine

32 Class Anthozoa Sea Anemone

33 Class Anthrozoa Metridium MouthMouth TentaclesTentacles PharynxPharynx SeptumSeptum Gastrovascular cavity

34 Symbiosis

35 Class Anthozoa Corals Protective skeleton of calcium carbonate Polyp retracts when not feeding

36 Zooxanthellae Photosynthetic dinoflagellates (brown) Live in corals Provide nutrients for coral by photosynthesis Mutualism

37 Corals Colony of interconnected polyps

38 Class Anothozoa Meandrina Brain Coral

39 Class Anothozoa Gorgonia Sea Fan

40 Class Anothozoa Tubipora Pipe Organ Coral

41 Class Anothozoa Actinodiscus Mushroom Coral

42 Class Anothozoa Acropora Staghorn Coral

43 Coral Reefs Formed over thousands of years from successive layers of coral skeleton deposits (calcium carbonate forms underwater mountains of coral animal skeletons) The underwater equivalent of the amazon jungle- very high species diversity and biomass Reefs contain sponges, colonial hydrozoans, anemones, many varieties of coral, fish, many types of worms we’ve not discussed, not to mention bryozoans, ctenophores, protists, bacteria, etc etc..

44 Coral Reef Ecosystem Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Photo © McGraw-Hill Higher Education, Barry Barker, Photographer

45 Anthozoa ScyphozoaCubozoa Hydrozoa Radial symmetry, cnidocytes, planula larva Septa divide gastrovascular cavity Medusa cuboidal Polyp stage reduced Loss of medusa Cladogram of Cnidaria

46 The End