1. Phylum Cnidaria (radially symmetric, 2 cell layers in body) Jellyfish and allies. These alternate 2 phases in their life cycle: the free-living medusoid phase (“jellyfish”), and a sessile hydroid phase. Both feed by capturing planktonic food using tentacles armed with a cnidarian speciality, the class of stinging cell called nematocysts. Some are entangling, some inject barbed points to anchor, some inject toxins.

2. The main classes are: Hydrozoa: various medusoid radiations, often with several body forms fused into one animal ie Physalia physalis, the infamous, portugese man o’war (avoid!). Scyphozoa = jellyfish, Aurelia aurita in the common UK moon jelly (harmless to humans) Anthozoa: sessile forms: sea anemones, corals, sea fans Cubozoa: sea wasp

3. Cnidirians Overview: Life Without a Backbone Invertebrates –Are animals that lack a backbone –Account for 95% of known animal species Figure 33.1

4. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Evolutionary Relationships of Cnidaria

5. The Radiate Animals Tissue level of organization No anterior or posterior Terms of direction defined based on the position of the mouth Oral/aboral ends Biradial symmetry- single plane, passing through a central axis, divides the organism into mirror images Advantageous b/c sensory receptors evenly distributed. Diploblasic tissue level organization- similar cells are organized into tissues, and all cells are derived from two embryonical layers (ectoderm and endoderm/gastrodermis)

6. A review of animal phylogeny Ancestral colonial choanoflagellate Eumetazoa Bilateria Deuterostomia Porifera Cnidaria Other bilaterians (including Nematoda, Arthropoda, Mollusca, and Annelida) Echinodermata Chordata Figure 33.2

7. Exploring invertebrate diversity PORIFERA (5,500 species) A sponge CNIDARIA (10,000 species) A jelly PLACOZOA (1 species)KINORHYNCHA (150 species) 0.5 mm A placozoan (LM) A kinorhynch (LM) 250 µm PLATYHELMINTHES (20,000 species) ROTIFERA (1,800 species) A marine flatworm A rotifer (LM) ECTOPROCTA (4,500 species) PHORONIDA (20 species) Ectoprocts Phoronids Figure 33.3

8. Cnidarians have radial symmetry, a gastrovascular cavity, and cnidocytes All animals except sponges –Belong to the clade Eumetazoa, the animals with true tissues Phylum Cnidaria –Is one of the oldest groups in this clade

9. Cnidarians –Have diversified into a wide range of both sessile and floating forms including jellies, corals, and hydras –But still exhibit a relatively simple diploblastic, radial body plan

10. The Body Wall Two cellular layers Epidermis- epithelio-muscular cells Mesoglia- noncellular gel and is abundant in the Medussa Gastrodermis- –gland cells for the production and release of enzymes. –Flagellated nutitive muscular cells that contain food vacuoles

11. 9-7 Fig. 9.9 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Cnidarian Body Wall

12. Phylum Cnidaria- Nematocysts Name comes from the presence of specialized cells used in defense, feeding and attachment. Cnidosytes contain stinging organelles called Nematocysts.

13. Tentacle “Trigger” Nematocyst Coiled thread Discharge Of thread Cnidocyte Prey Figure 33.6 Cnidarians are carnivores –That use tentacles to capture prey The tentacles are armed with cnidocytes –Unique cells that function in defense and the capture of prey

14. Cnidocyte Structure and Nematocyst Discharge 9-8 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Fig. 9.10

15. The basic body plan of a cnidarian –Is a sac with a central digestive compartment, the gastrovascular cavity A single opening –Functions as both mouth and anus

16. There are two variations on this body plan –The sessile polyp and the floating medusa Mouth/anus Tentacle Gastrovascular cavity Gastrodermis Mesoglea Epidermis Tentacle Body stalk Mouth/anus Medusa Polyp Figure 33.5

17. Gastrovascular Cavity Receives and digest food Single opening serves as the mouth and anus Tentacles surrounding the opening aid in feeding.

18. CV cavity continue Simplicity of body plan Hydras and other cnidirians don not require a true circulatory systems Body wall two cell thick encloses CV cavity Serves both in digestion and distribution of substances throughout the body Extend to tentacles

19. The phylum Cnidaria is divided into four major classes

20. Cladogram of Cnidarian Taxonomy 9-17 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Fig. 9.23

21. –Hydrozoa, Scyphozoa, Cubozoa, and Anthozoa (a) These colonial polyps are members of class Hydrozoa. (b) Many species of jellies (class Scyphozoa), including the species pictured here, are bioluminescent. The largest scyphozoans have tentacles more than 100 m long dangling from a bell-shaped body up to 2 m in diameter. (c) The sea wasp (Chironex fleckeri) is a member of class Cubozoa. Its poison, which can subdue fish and other large prey, is more potent than cobra venom. (d) Sea anemones and other members of class Anthozoa exist only as polyps. Figure 33.7a–d

22. Alterations of Generations Typical cnidarian alternates b/w a hydroid stage (polyp) and a swimming medusa (jellyfish) stage. Polyp – assexual stage Medusa- sexual stage In some cnidarian classes either the polyp or the medussa is reduced or missing.

23. Generalized Cnidarian Life Cycle

24. Hydrozoans Most hydrozoans –Alternate between polyp and medusa forms Feeding polyp Reproductive polyp Medusa bud ASEXUAL REPRODUCTION (BUDDING) Gonad Medusa MEIOSIS FERTILIZATION SEXUAL REPRODUCTION Egg Sperm Developing polyp Portion of a colony of polyps Mature polyp Planula (larva) Key Haploid (n) Diploid (2n) 1 mm Zygote Figure 33.8 A colony of interconnected polyps (inset, LM) results from asexual reproduction by budding. 1 Some of the colony’s polyps, equipped with tentacles, are specialized for feeding. 2 Other polyps, specialized for reproduction, lack tentacles and produce tiny medusae by asexual budding. 3 The medusae swim off, grow, and reproduce sexually. 4 The zygote develops into a solid ciliated larva called a planula. 5 The planula eventually settles and develops into a new polyp. 6

25. Hydrazoa Obelia Structure and Life Cycle 9-10 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Fig. 9.12

26. Structure of Gonionemus Medusa 9-11 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Fig. 9.13b

27. CNIDARIA Class Hydrozoa Feather hydroid (Halocordyle disticha, formerly called Pennaria tiarella), from Bermuda Tiny, white tufts along lateral branches of the colony are individual polyps Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display Photo Copyright © Diane R. Nelson

28. CNIDARIA Class Hydrozoa Fire coral (Millepora complanata), golden brown with white growing tips This is a hydrocoral, not a “true” stony coral Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display Photo Copyright © Diane R. Nelson

29. CNIDARIA Class Hydrozoa Fire coral (Millepora complanata), common in the Caribbean Polyps on surface and along edges (“fuzz”) are loaded with toxic stinging nematocysts Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display Photo Copyright © Diane R. Nelson

30. CNIDARIA Class Hydrozoa Portuguese Man-o- War (Physalia physalia) This is a colony with several types of polyps: gastrozooids, gonozooids, and dactylozooids Highly toxic Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display Photo Copyright © Diane R. Nelson

31. Scyphozoans In the class Scyphozoa –Jellies (medusae) are the prevalent form of the life cycle –Polyp reduced or absent –Gametes produced gastrodermally –Cnidocytes present in gastrodermis and epidermis –Marine –Examples- aurelia

32. Structure of Scyphozoan Medusa 9-12 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Fig. 9.15 Source: After L. H. Hyman, Biology of the Invertebrates, Copyright © 1940 McGraw-Hill Publishing Co.

33. Aurelia Life History 9-13 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Fig. 9.16

34. CNIDARIA Class Scyphozoa Sea thimble jellyfish (Linuche unguiculata), Honduras Tiny jellyfish (< 1 inch) that swarm in the spring Adults and larvae (“sea lice”) may cause a severe skin reaction in humans Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display Photo Copyright © Diane R. Nelson

35. CNIDARIA Class Scyphozoa Upside down jellyfish (Cassiopea xamachana) from Bermuda, with zooxanthellae This specimen is swimming up to the surface, where its reflection is visible Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display Photo Copyright © Diane R. Nelson

36. CNIDARIA Class Scyphozoa Jellyfish (Mastigias sp., family Rhizostomeae) from Jellyfish Lake in Palau, western Pacific These jellyfish have lost their ability to sting and depend on zooxanthellae for nutrition Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display Photo Copyright © Diane R. Nelson

37. Anthozoans Class Anthozoa includes the corals and sea anemones –Which occur only as polyps

38. Longitudinal Section of a Stony Coral Polyp 9-15 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Fig. 9.20

39. Structure of an Anemone 9-14 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Fig. 9.19 Charles Lytle and J. E. Wodsedalek, General Zoology Laboratory Guide, 11 th ed., Complete Version, New York, McGraw- Hill. Reprinted by permission of The McGraw-Hill Companies.

40. CNIDARIA Class Anthozoa Sea fan (Subergorgia sp.) from the Solomon Islands This is a colony, with reticulated branches in one plane, at right angles to the prevailing current Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display Photo Copyright © Diane R. Nelson

41. CNIDARIA Class Anthozoa Gorgonian sea fan (Plexuaridae) on a reef wall in Fiji Individual polyps in the colony filter plankton from the water column Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display Photo Copyright © Diane R. Nelson

42. CNIDARIA Class Anthozoa Polyp of a tree fern or palm coral (Clavularia sp.) with pinnate tentacles, in the Solomon Islands Large sheets of these polyps are attached by a common stolon to the substrate Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display Photo Copyright © Diane R. Nelson

43. CNIDARIA Class Anthozoa Divaricate tree coral (Dendronephthya sp.), from Fiji These bushy or tree-like soft corals (alcyonaceans) are found only in the Pacific Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display Photo Copyright © Diane R. Nelson

44. CNIDARIA Class Anthozoa Close-up of an alcyonacean tree coral (Dendronephthya sp.) Spicules, the small white rod-shaped structures, are embedded in the tissue and aid in supporting the colony Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display Photo Copyright © Diane R. Nelson

45. CNIDARIA Class Anthozoa Note the pinnate tentacles of this octocoral, a gorgonian sea rod from Belize Sea rod colonies can be identified more easily when their polyps are retracted Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display Photo Copyright © Diane R. Nelson

46. CNIDARIA Class Anthozoa Corky sea finger (Briareum asbestinum), common in the Caribbean Sea rod in front has polyps extended, while rod in back has polyps retracted, revealing purple color Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display Photo Copyright © Diane R. Nelson

47. CNIDARIA Class Anthozoa Sea anemone (Heteractis sp.) from Fiji Note column of anemone and tentacles along margin This anemone may be host to symbiotic anemonefish Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display Photo Copyright © Diane R. Nelson

48. CNIDARIA Class Anthozoa The giant anemone or purple-tipped anemone (Condylactis gigantea) often harbors cleaning shrimp among its tentacles Common in Bermuda and the Caribbean Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display Photo Copyright © Diane R. Nelson

49. CNIDARIA Class Anthozoa Aerial view of coral reefs in Fiji Dark blue on right is deep water White is the edge of the reef Lighter color is the reef flat Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display Photo Copyright © Diane R. Nelson

50. CNIDARIA Class Anthozoa Elkhorn coral (Acropora palmata), from the Caribbean Wide branches are extended upward, catching the sunlight for the zooxanthellae in the coral tissues Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display Photo Copyright © Diane R. Nelson

51. CNIDARIA Class Anthozoa Brain coral (Diploria strigosa) in Bermuda, with black band disease The black line marks the cyanophyte alga (Phormidium corallyticum) that kills the coral colony Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display Photo Copyright © Diane R. Nelson

52. CNIDARIA Class Anthozoa Brain coral (Diploria strigosa), common in Bermuda and the Caribbean Healthy coral is golden-brown due to the presence of symbiotic zooxanthellae Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display Photo Copyright © Diane R. Nelson

53. CNIDARIA Class Anthozoa Coral aggression between two stony corals in Bermuda Montastrea annularis (top) and Diploria strigosa (bottom) compete for space, leaving a dead zone (white) between them Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display Photo Copyright © Diane R. Nelson

54. CNIDARIA Class Anthozoa Extended slender polyps of the stony coral Goniopora sp., found in Fiji and the western Pacific Polyps are extended during the day Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display Photo Copyright © Diane R. Nelson

55. CNIDARIA Class Anthozoa Orange cup coral (Tubastraea coccinea) from Bonaire in the Caribbean These ahermatypic corals extend their polyps at night to feed on plankton Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display Photo Copyright © Diane R. Nelson

56. CNIDARIA Class Anthozoa Coral bleaching in star coral (Montastrea annularis) in the Caribbean Golden brown color indicates healthy tissue White area has lost zooxanthellae Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display Photo Copyright © Diane R. Nelson

57. CNIDARIA Class Anthozoa Coral bleaching in star coral (Montastrea annularis) in the Caribbean Loss of zooxanthellae due to higher water temperatures results in lighter color Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display Photo Copyright © Diane R. Nelson

58. CNIDARIA Class Anthozoa Elliptical star coral (Dichocoenia stokesii), common in the Caribbean Dome-shaped colonies with elliptical corallites Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display Photo Copyright © Diane R. Nelson

59. CNIDARIA Class Anthozoa Close-up of the raised corallites of Caribbean elliptical star coral (Dichocoenia stokesii) in the daytime Polyps are extended at night to feed on plankton Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display Photo Copyright © Diane R. Nelson

60. CNIDARIA Class Anthozoa Close-up of giant star coral (Montastrea cavernosa) during the day with polyps retracted Common in the Caribbean Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display Photo Copyright © Diane R. Nelson

61. CNIDARIA Class Anthozoa Close-up of giant star coral (Montastrea cavernosa) with polyps extended at night to feed on plankton Common in the Caribbean Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display Photo Copyright © Diane R. Nelson

62. CNIDARIA Class Anthozoa Banded tube-dwelling anemone (Arachnanthus nocturnus) from Bonaire Cerianthid, or burrowing anemone Nocturnal, Caribbean Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display Photo Copyright © Diane R. Nelson

63. CNIDARIA Class Anthozoa Sea pen (Pteroeides sp.) from the Solomon Islands This is a colony that lives anchored in the sand, turning at right angles to the prevailing current Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display Photo Copyright © Diane R. Nelson

64. Class Cubozoa A few a lethal to humans - NEVER EVER swim with box jellies (sea wasps)

65. Characteristics of Ctenophora 1)Radially or biradial Symmetrical. 2)Body multicellular, few tissues, some organs and organelles. 3)Body contains an internal cavity and a mouth and anal pores. 4)Swims by means of plates of cilia (the combs) 5)Reproduction mostly sexual as hermaphrodites, occasionally asexual. 6)Has a well developed subepidermal nerve net. 7)Has a distinct larval stage which is planktonic. 8)Lives in marine environments. 9)All are carnivorous.

66. Ctenophore Mnemiopsis 9-16 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Fig. 9.22

67. Ctenophora Anatomy Comb Jellies

68. Ctenophora