Phylum Cnidaria

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Phylum Cnidaria

• Hydra, jellyfish, coral, sea anemones

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Phylum Cnidaria

• Examples?
• Sea anemones
• Corals
• Sea Pen
• Sea Fan
• Sea Plume
• Hydra
• Jelly fish
• Portuguese Man o War
• Box Jelly Fish

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I. Body Structure

• A. Polymorphism
• more than one body form
• 1. Polyp
• 2. Medusa

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B. Polyp

• Tube with tentacles
• around the mouth
• Sessile

Coral polyp
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Polyp (sea anemone)
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Mythical Hydra
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Polyp (Hydra)
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Perseus slays the Gorgon Medusa
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C. Medusa

• Umbrella shape
• Tentacles around mouth
• Motile, Free-swimming

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D. Tentacles

• Have nematocysts
• (stinging
• cells)
• Coiled thread discharges
• like a harpoon
• Contains neurotoxin
• Paralyzes prey

Discharged nematocyst
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e. Cnidarian Life Cycle
Stage 1 Adult Medusa Stage 2 Planula
larva Stage 3 - Polyp
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Discharged nematocyst
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II. Level of Organization

• A. Tissue
• B. No organs

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III. Symmetry
Radial
Compass jellyfish
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IV. Habitat

• A. Aquatic
• 1. Most Marine
• 2. Few fresh-water

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V. Feeding

• A. Carnivores
• (predators)
• B. Process of feeding
• 1. Tentacles sting prey with
• nematocysts
• 2. Tentacles grab prey
• 3. Prey pulled into mouth

Lions mane eats another jelly
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Process of feeding

• 4. Prey stuffed into gastro-vascular cavity
  (GVC)
• 5. GVC makes enzymes, extra-cellular digestion
• 6. Undigested food back out mouth

incomplete digestive tract (no anus)
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Lions mane jellyfish eating
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VI. Respiration

• Via diffusion
• Body is two cell layers
• thick

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VII. Internal Transport

• Via diffusion

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VIII. Excretion

• Via diffusion

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IX. Response

1. No cephalization or nervous system
2. Nerve net around mouth

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IX. Response

• C. Sensory cells
• 1. Chemoreceptors (chemicals)
• 2. Thigmoreceptors (touch)
• 3. Photoreceptors (light)
• Ocelli (eyespots)
• 4. Statocysts (balance)

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X. Locomotion

• Medusa motile, free-swimming
• Polyps sessile
• Exceptions
• 1. Hydra tumbles on tentacles
• 2. Sea anemones glide on pedal disc

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XI. Reproduction

• 1. Asexual
• budding from polyps or medusae
• 2. Sexual
• a. Medusae release sperm eggs
• b. Some monoecious, some dioecious
• c. Larvae free-swimming

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XII. Ecological Role

• Predators and prey
• Neurotoxins in medical research
• Coral jewelry, building, reefs
• Coral reefs - habitat for many
• -great biodiversity
• - protect coastline
• E. Symbiosis with other organisms

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Cnidaria Body Structure
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Class Anthozoa Sea Anemones
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Sea Anemones (with sea urchins)
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Sea Anemones Clown fish with sea anemone
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Clown fish eggs with sea anemone
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Clown fish with sea anemone
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Giant Sea Anemone
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Rosy Sea Anemone
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Class Anthozoa Corals
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Brain Coral
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Coral
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Colt Coral
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Elkhorn Coral
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Cabbage Coral
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Flower Coral
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Feather Coral
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Gorgonian Fan Coral
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Lamellina Coral
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Sun Coral
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Subergorgia Coral
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Soft Coral
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Sea Pen
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Sea Fan
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Sea Plume
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Class Hydrozoa Green Hydra
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Hydra
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Brown Hydra with buds
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Brown Hydra eating
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Hydra eating Daphnia

• Hydra eats Daphnia

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Class Scyphozoa True Jellyfish
Fried egg jelly
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Jellyfish
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Jellyfish
Red-eyed medusa
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Jellyfish
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Jellyfish
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Jellyfish
Lions mane
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Jellyfish
Purple lions mane
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Upside down Jelly fish
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Upside down Jelly fish
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Sea Nettle
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Jelly and diver
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Giant Jelly off Coast of Japan
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Beached Jelly fish
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(No Transcript)
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Jelly fish Humor
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Portuguese Man 0 War(a Hydrozoan), NOT a true
jelly fish
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Portuguese Man 0 War
Tentacles of Physalia physalis
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Portuguese Man o War vs. Box Jelly fish
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Class Cubozoa Box Jellyfish
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Chironex fleckerithe Box jelly fish