1. 13-1 CHAPTER 13 Radiate Animals Phylum Cnidaria Radiate Animals Phylum Cnidaria

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3. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Phylum Cnidaria Fossil specimens dated to over 700 million years ago General Characteristics Soft bodied Carnivorous Stinging tentacles Examples: Jellyfish, sea anemones

4. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 13-4 Phylum Cnidaria Classes of Cnidaria Classes of Cnidaria Hydrozoa (Portuguese Man-of-War, Hydra) Hydrozoa (Portuguese Man-of-War, Hydra) Scyphozoa (True Jellyfish - Aurelia) Scyphozoa (True Jellyfish - Aurelia) Anthozoa (Sea Anenome, Corals) Anthozoa (Sea Anenome, Corals)

5. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 13-5 Phylum Cnidaria Characteristics of Phylum Cnidaria All are aquatic and mostly marine All are aquatic and mostly marine Symmetry Symmetry Radial Radial Two body types Two body types Free-swimming medusa Free-swimming medusa Sessile polyps Sessile polyps Acoelomates - No coelom Acoelomates - No coelom Diploblastic Diploblastic Blind (Incomplete) Gut Blind (Incomplete) Gut

6. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 13-6 Phylum Cnidaria Tentacles usually encircle mouth or oral region Tentacles usually encircle mouth or oral region Equipped with specialized cells: cnidocytes Equipped with specialized cells: cnidocytes Cnidocytes: stinging cells located on their tentacles Cnidocytes: stinging cells located on their tentacles Nematocyst: stinging organelle, poison-filled structure that contains a tightly coiled dart. Nematocyst: stinging organelle, poison-filled structure that contains a tightly coiled dart. Muscular contractions via epitheliomuscular cells Muscular contractions via epitheliomuscular cells layers of longitudinal and circular fibers layers of longitudinal and circular fibers Sense organs for balance (statocysts) and photosensitivity (ocelli) Sense organs for balance (statocysts) and photosensitivity (ocelli)

7. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 13-7 Phylum Cnidaria Nerve net Nerve net Simple nervous system, no brain Simple nervous system, no brain Interconnected Neurons Interconnected Neurons Used to sense physical contact Used to sense physical contact Asexual reproduction Asexual reproduction Budding in polyps Budding in polyps Sexual reproduction Sexual reproduction By gametes in all medusae and some polyps By gametes in all medusae and some polyps Monoecious or Dioecious Monoecious or Dioecious No excretory or respiratory system No excretory or respiratory system

8. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 13-8 A.Hermit crab uses cnidrian as protection B.Showing growth on host shell

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10. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 13-10 Phylum Cnidaria Form and Function Cnidaria have two basic body plans: polyp and medusa Cnidaria have two basic body plans: polyp and medusa Polyp Polyp Internal Body Cavity Internal Body Cavity Adaptation to a sedentary life Adaptation to a sedentary life Tubular body with the mouth directed upward and surrounded by tentacles Tubular body with the mouth directed upward and surrounded by tentacles Mouth leads into a blind-gut cavity Mouth leads into a blind-gut cavity Reproduce asexually by budding, fission, or pedal laceration Reproduce asexually by budding, fission, or pedal laceration

11. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 13-11 Phylum Cnidaria - Medusa Medusa Medusa Bell or umbrella-shaped Bell or umbrella-shaped Usually free-swimming Usually free-swimming Mouth directed downward Mouth directed downward Tentacles may extend down from rim of umbrella Tentacles may extend down from rim of umbrella Medusae equipped with statocysts (direction) and ocelli (light/vision) Medusae equipped with statocysts (direction) and ocelli (light/vision)

12. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 13-12 Phylum Cnidaria Body Wall Cnidarian body Cnidarian body Outer epidermis Outer epidermis Inner gastrodermis (gastrovascular cavity = gut) Inner gastrodermis (gastrovascular cavity = gut) Layers separated by mesoglea Layers separated by mesoglea Mesoglea Mesoglea Gelatinous (at least 95% water) - jellylike Gelatinous (at least 95% water) - jellylike Continuous, extending through body and tentacles Continuous, extending through body and tentacles Supports body Supports body Thickness varies Thickness varies

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14. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 13-14 Life Cycles Polyps and medusae play different roles in the cnidarian life cycle Polyps and medusae play different roles in the cnidarian life cycle Typically, zygote develops into a motile planula larva Typically, zygote develops into a motile planula larva Planula settles, and metamorphoses into a polyp Planula settles, and metamorphoses into a polyp Produce other polyps asexually Produce other polyps asexually Polyps eventually produce a free-swimming medusa by asexual reproduction Polyps eventually produce a free-swimming medusa by asexual reproduction Budding Budding Phylum Cnidaria

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17. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 13-17 Phylum Cnidaria Cnidocytes Many cnidarians are effective predators Many cnidarians are effective predators Possibly due to presence of a unique cell type, the cnidocyte (discharged = cnidae) Possibly due to presence of a unique cell type, the cnidocyte (discharged = cnidae) Nematocyst- inside cnidocytes, poison-filled stinging structure Nematocyst- inside cnidocytes, poison-filled stinging structure

18. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 13-18 Phylum Cnidaria Nematocyts Nematocyts Tiny capsules containing a coiled filament Tiny capsules containing a coiled filament End of capsule is covered End of capsule is covered Filament may have tiny barbs or spines Filament may have tiny barbs or spines Tactile stimulation of cnidocil, causes nematocyst to discharge Tactile stimulation of cnidocil, causes nematocyst to discharge After discharge, cnidocyte is absorbed and another develops After discharge, cnidocyte is absorbed and another develops

19. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 13-19 Phylum Cnidaria Mechanism of Nematocyst Discharge Mechanism of Nematocyst Discharge When stimulated, water rushes into the capsule When stimulated, water rushes into the capsule The operculum (cap) opens and rapidly launches the filament The operculum (cap) opens and rapidly launches the filament Barbs inject poison into prey Barbs inject poison into prey Only a few jellyfish - including the Portuguese man-of- war can seriously harm humans Only a few jellyfish - including the Portuguese man-of- war can seriously harm humans Topical Solutions if stung: Topical Solutions if stung: acidic (vinegar) acidic (vinegar) Urine - only if urine is acidic?? Most urine is sterile. Urine - only if urine is acidic?? Most urine is sterile. Apply heat or ice for pain (also denatures toxins) Apply heat or ice for pain (also denatures toxins) Salt water should be applied to remove any excess toxins. Salt water should be applied to remove any excess toxins.

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21. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 13-21 Discharged cnidae recoiled

22. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 13-22 Phylum Cnidaria Feeding and Digestion Polyps Polyps Typically carnivorous Typically carnivorous Catch prey with tentacles and pass them to the gastrovascular cavity Catch prey with tentacles and pass them to the gastrovascular cavity Gland cells discharge enzymes to begin extracellular digestion Gland cells discharge enzymes to begin extracellular digestion Intracellular digestion continues in the gastrodermis Intracellular digestion continues in the gastrodermis

23. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 13-23 Phylum Cnidaria Nerve Net Allow cnidarians to detect stimuli Allow cnidarians to detect stimuli Unlike higher animals, Unlike higher animals, Nerve nets have neurotransmitters on both sides of the synapses Nerve nets have neurotransmitters on both sides of the synapses Allowing transmission in either direction Allowing transmission in either direction No myelin sheath on axons - like humans No myelin sheath on axons - like humans Nervous system also has Statocysts and Ocelli Nervous system also has Statocysts and Ocelli

24. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 13-24 Phylum Cnidaria Class Hydrozoa: Animals Class Hydrozoa: Animals Hydra Hydra Found in fresh water Found in fresh water Worldwide distribution (16 species in North America) Worldwide distribution (16 species in North America) Body is a cylindrical tube Body is a cylindrical tube Ring of 6–10 hollow tentacles encircles mouth Ring of 6–10 hollow tentacles encircles mouth Portuguese Man-of-War Portuguese Man-of-War Floats on surface (air bladder) Floats on surface (air bladder) Tentacles reach up to 10 meters Tentacles reach up to 10 meters Contains polyp colonies and medusa Contains polyp colonies and medusa

25. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 13-25 Phylum Cnidaria Class Hydrozoa Most marine and colonial with both polyp and medusa forms (polyp form dominates) Most marine and colonial with both polyp and medusa forms (polyp form dominates) Hydra, hydrozoan, hydroid Hydra, hydrozoan, hydroid Medusa have velum Medusa have velum Layer inside bell to close off outside Layer inside bell to close off outside Colonial Obelia Colonial Obelia Typical hydroid has a base, a stalk, and one or more individual polyp animals Typical hydroid has a base, a stalk, and one or more individual polyp animals Feeding polyps with tentacles around mouth= hydranths Feeding polyps with tentacles around mouth= hydranths In Obelia, the medusae buds are formed by a reproductive polyp called a gonangium In Obelia, the medusae buds are formed by a reproductive polyp called a gonangium

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29. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 13-29 Medusa D. Developing Polyp from Planula: Frustule = bud

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32. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 13-32 Phylum Cnidaria Hydras reproduce sexually and asexually Hydras reproduce sexually and asexually Asexual reproduction Asexual reproduction Budding Budding Most hydra are dioecious Most hydra are dioecious Temporary gonads appear in autumn, stimulated by lower temperatures Temporary gonads appear in autumn, stimulated by lower temperatures Eggs and sperm shed externally, external fertilization Eggs and sperm shed externally, external fertilization Cyst forms around embryo Cyst forms around embryo Encysted form endures the winter, then young hydras hatch in the spring Encysted form endures the winter, then young hydras hatch in the spring

33. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 13-33 Hydra w/ developing bud and ovary/egg

34. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 13-34 Portuguese man-of-war Colony Secrete powerful neurotoxin - Class Hydrozoa

35. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Differences between Hydrozoa and Scyphozoa Hydrozoa Have Velum - protecting muscle on inward side of bell Colonial Stages Mostly Polyp life form Medusa, if present, are usually small Small amounts of mesoglea and no cells 4 tentacles Scyphozoa Large Medusa forms Polyps are sedentary No velum Cells present in mesoglea More complex More tentacles Large amount of mesoglea

36. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 13-36 Class Hydrozoa: Hydrocorals - form calcareous skeletons to resemble true coral. B. “Fire Coral” - Nematocysts cause burning sensation to human skin

37. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 13-37 Phylum Cnidaria Class Scyphozoa Most of the larger jellyfishes belong to this class Most of the larger jellyfishes belong to this class Nearly all float in open sea Nearly all float in open sea Bells vary in shape and size Bells vary in shape and size Composed mostly of mesoglea Composed mostly of mesoglea Lack subumbrellar membrane - velum found in hydrozoan medusae Lack subumbrellar membrane - velum found in hydrozoan medusae

38. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 13-38 Class Scyphozoa Giant jellyfish

39. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 13-39 Moon Jellyfish (Aurelia)

40. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 13-40 Phylum Cnidaria - Scyphozoa Phylum Cnidaria - Scyphozoa Reproduction methods Reproduction methods Asexual - Similar to other cnidarians. Budding Asexual - Similar to other cnidarians. Budding But also use Strobilation - asexual budding of saucerlike buds that develop into medusa. But also use Strobilation - asexual budding of saucerlike buds that develop into medusa.

41. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 13-41 Life Cycle of Aurelia, marine scyphozoan

42. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 13-42 Phylum Cnidaria Class Anthozoa Lack a medusa stage Lack a medusa stage All marine, in both deep and shallow water, and vary in size All marine, in both deep and shallow water, and vary in size Examples: sea anemones, sea corals Examples: sea anemones, sea corals

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45. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 13-45 Phylum Cnidaria - Anthozoa No special organs for respiration or excretion Sea Anemones Polyps larger and heavier than hydrozoan polyps Polyps larger and heavier than hydrozoan polyps Attach to shells, rocks, timber, etc. by pedal discs Attach to shells, rocks, timber, etc. by pedal discs

46. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 13-46 Phylum Cnidaria - Anthozoa Some burrow in mud or sand Some burrow in mud or sand Crown of tentacles surrounds the flat oral disc Crown of tentacles surrounds the flat oral disc Slit-shaped mouth leads into a pharynx Slit-shaped mouth leads into a pharynx Transports oxygen, removes wastes, and maintains fluid pressure for a hydrostatic skeleton Transports oxygen, removes wastes, and maintains fluid pressure for a hydrostatic skeleton When in danger, water rapidly expelled through pores as the anemone contracts to a small size When in danger, water rapidly expelled through pores as the anemone contracts to a small size

47. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 13-47 Sea Anemone being attacked by a Sea Star Can Sea Anemones run?

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50. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 13-50 Phylum Cnidaria - Anthozoa Reproduction of Sea Anemones Reproduction of Sea Anemones Some dioecious, some monoecious Some dioecious, some monoecious Monoecious species - produce sperm first and eggs later Monoecious species - produce sperm first and eggs later Fertilization is external or in gastrovascular cavity Fertilization is external or in gastrovascular cavity Zygote becomes a ciliated larva Zygote becomes a ciliated larva Pedal laceration, small pieces of pedal disc break off and regenerate a small anemone Pedal laceration, small pieces of pedal disc break off and regenerate a small anemone Longitudinal and transverse fission, and budding occur Longitudinal and transverse fission, and budding occur

51. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 13-51 Closed during day, open to feed at night

52. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 13-52 Polyp of Coral

53. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 13-53 Boulder Star Coral

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55. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 13-55 A soft coral on Pacific Coral Reef

56. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 13-56 Sea Fan Red Whip Coral Horny Coral

57. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 13-57 Phylum Cnidaria Coral Reefs Coral Reefs Great diversity of organisms (under rainforest) Great diversity of organisms (under rainforest) Plants and animals are limited to top layer Plants and animals are limited to top layer Above the calcium carbonate deposits Above the calcium carbonate deposits Hermatypic (reef forming) corals and coralline algae (precipitate calcium carbonate) form most coral reefs Hermatypic (reef forming) corals and coralline algae (precipitate calcium carbonate) form most coral reefs Require warmth, light, and salinity of undiluted sea water (contains calcium) Require warmth, light, and salinity of undiluted sea water (contains calcium) Limited to shallow waters between 30 degrees north and 30 degrees south latitude Limited to shallow waters between 30 degrees north and 30 degrees south latitude Photosynthetic zooxanthellae live in their tissues Photosynthetic zooxanthellae live in their tissues Provide food for corals and recycle phosphorus and nitrogenous wastes Provide food for corals and recycle phosphorus and nitrogenous wastes

58. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 13-58 Barrier Reef

59. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 13-59 Phylum Cnidaria - Human Impact Nutrients from fertilizer and sewage threaten coral reefs with excessive algal growth - or by killing zooxanthellae, which leads to coral bleaching. Nutrients from fertilizer and sewage threaten coral reefs with excessive algal growth - or by killing zooxanthellae, which leads to coral bleaching. Persian Gulf reefs have withstood surprising amounts of oil pollution Persian Gulf reefs have withstood surprising amounts of oil pollution Coral reefs in many areas are threatened by factors mostly of human origin Coral reefs in many areas are threatened by factors mostly of human origin Higher atmospheric concentrations of carbon dioxide (from burning hydrocarbon fuels) tends to acidify ocean water, which makes precipitation of CaCO 3 by corals more difficult metabolically Higher atmospheric concentrations of carbon dioxide (from burning hydrocarbon fuels) tends to acidify ocean water, which makes precipitation of CaCO 3 by corals more difficult metabolically