1 Unit 4.2 Phylum Cnidaria

2 Phylum Cnidaria Radial symmetry Mouth at oral end surrounded by tentacles. One opening into and out of gastrovascular cavity. Cnidocytes that discharge nematocysts Two body forms –Polyp –Medusa Two germ layers Nerve net Still no circulatory or respiratory systems

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

11 Class Hydrozoa Freshwater & marine. Cnidocytes present only on epidermis. Medusa (if present) with a muscular velum that aids in propulsion. Asexual reproduction by budding. Sexual reproduction via gametes produced by epidermis & released into water. Hydra, Ctenophores, Obelia, Man-of-War

12 Class Hydrozoa HydraSpermariesSpermaries OvariesOvaries EncapsulatedembryoEncapsulatedembryo Sexual cycle Asexual cycle BuddingBudding

13 GastrovascularcavityGastrovascularcavity EpidermisEpidermis MesogleaMesoglea GastrodermisGastrodermis Hydra Body Wall

14

15

Obelia Freshwater or marine. Live in colonies rather than free living like hydra. Colonies contain two types of polyps, feeding and reproductive. Dual stage life cycle like other Cnidarians. 16

Obelia 17

Obelia 18

19 Obelia MedusaeGonangium Medusa bud

20 Class Hydrozoa Gonionemus

21 Velum

22 Class Hydrozoa Physalia

Commonly called the Portuguese Man-of- War. Not a jellyfish or even a single organism. Made of a colony of hydrozoans that perform specialized functions. 23

Class Hydrozoa Physalia Gastrozooids – Feeding & digestion. Dactylozooids – Prey capture. Gonozooids – Reproduction. Pneumatophore – Gas-filled float. 24

Class Hydrozoa Physalia 25

Class Scyphozoa 26

27 Class Scyphozoa True Jellyfish Tentacles up to 70 meters in length Cnidocytes present in gastrodermis & epidermis Thick mesoglea contains amoeboid cells Gametes produced by gastrodermis All marine

28 Class Scyphozoa Aurelia – Moon Jellies

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

30 Fig

31 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.

32 Class Cubozoa GonadGonad TentacleTentacle PedaliumPedalium

33 Class Cubozoa The Box Jellyfish

The most venomous poison known to man. One brush against the skin will inject enough venom to put a full grown adult in the hospital for over a week. Even a full morphine drip can not relieve the pain. 34

Class Cubozoa The Box Jellyfish 35

Class Cubozoa The Box Jellyfish 36

37 Class Anthozoa Sea Anemones & Coral Medusa stage virtually absent Solitary or colonial Some produce protective skeletons Cnidocytes on tentacles and lining the gastrovascular cavity Mesoglea contains amoeboid cells like all other Cnidarians All Marine

38 Class Anthozoa Sea Anemone

39 Class Anthozoa Metridium MouthMouth TentaclesTentacles PharynxPharynx SeptumSeptum Gastrovascular cavity

40 Symbiosis

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

42 Zooxanthellae Photosynthetic dinoflagellates (brown) Live in corals Provide nutrients for coral by photosynthesis while gaining a home Mutualism

43 Corals Colony of interconnected polyps

44 Class Anthozoa Meandrina Brain Coral

45 Class Anthozoa Gorgonia Sea Fan

46 Class Anthozoa Tubipora Pipe Organ Coral

47 Class Anthozoa Actinodiscus Mushroom Coral

Class Anthozoa Acropora Staghorn Coral 48

49 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..

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

51 Anthozoa ScyphozoaCubozoa Hydrozoa Radial symmetry & cnidocytes All marine Medusa cuboid Polyp stage reduced Loss of medusa Cladogram of Cnidaria

52 The End