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TRANSCRIPT
Cnidariansfrom Modern Latin cnida, from Greek
knide "nettle", from stem of knizein "to
scratch scrape".
Examples● Jellyfish
● Corals
● Sea Anemone
● Hydra
Characteristics● Radial Symmetry
● Stinging Cells (Cnidocyte)
● Two different Body Plans During Life Cycle (exceptions)
● Polyp
● Medusa
Structure and Function● Cnida – Stinging Organelle
● Nematocysts● Spearing Cnida
● Generally on Tentacles
The Sting
• So what would you do if you were stung by a jellyfish?
• Jelly Fish Invasion
Yummy Nematocysts● Leatherback Sea Turtle
Why not use the toxin?
● Nudibranchs – eats cnidocytes and stores the toxin within its body, which turns orange in color… warning to all predators!!
True Jellyfish (Class Scyphozoa)● Predominant life stage
● Medusa
● Generally not strong swimmers
● Photoreceptors
● Box Jellies Closely Related
Hydrozoans● Mostly Colonial
● Specialized Polyps● Feeding Polyp
● Reproductive Polyp
Anthozoans (Flower Animal)● Sea Anemones
● Polyps
● Larger, heavier and more complex than hydra
● Most 1.5 to 10cm in Diameter
● Deep and Shallow Water
● Retracts Tentacles If Disturbed
● Essentially Sessile
Anthopleura elegantissima
Anthozoan Cont. and Gorgonian● Corals
● Hard Corals● Secrete a skeleton of calcium carbonate (Reef Building Coral)
● Large Colonies of Small Polyps
● Gorgonians (Most Common Soft corals)
● Soft Corals● Colonies that look like plants
Nutrition and Digestion● Gastrovascular Cavity
● Digestion and movement of materials within animal
● Waste if forced back out of the mouth after digestion (Yum!)
Reproduction● Asexually
● Generally during polyp state resulting in more polyps
● Sexually
● Generally in the medusa stage
Life Cycle
Ecological Relationships● Predator-Prey
● Predator to many species (stinging cells)
● Prey to sea turtles, some fish and molluscs● Crown-of thorns sea star
feeds on coral
● Habitat Formation
● Coral reefs provide a solid surface
Ecological Relationships● Symbiotic Relationships
● Portuguese man-of-war and man-of-war fish
● Coral and zooxanthellae
● Hermit crab and anemone (Eupagurusprideauxi and Aamsiapalliata)