Cnidarians & Ctenophorans copyright cmassengale 1
copyright cmassengale CNIDARIANS copyright cmassengale 2
copyright cmassengale Phylum Cnidaria About 9000 species Most are marine (jellyfish, coral, sea anemones, Portuguese man-of war) Hydras are found in freshwater All have arm-like tentacles copyright cmassengale 3
Cnidarian Characteristics Radial symmetry Hollow gut -Gastrovascular cavity has single opening (serves as both mouth and anus) Two tissue layers (diploblastic) Outer epidermis and inner gastrodermis copyright cmassengale 4
Cnidarian Characteristics Either tubular or bell shaped Tentacles surround mouth Only animal with cnidocytes (stinging cells) found in the tentacles Nematocyst – coiled, harpoon-like stinger inside cnidocyte that shoots out copyright cmassengale 5
Cnidarian Characteristics Cnidocytes contain poison to paralyze prey Tentacles bring food into mouth Inner gastrodermis secretes digestive juices into gastrovascular cavity which digests food and circulates nutrients copyright cmassengale 6
Extracellular Digestion Food digested outside of cells copyright cmassengale 7
copyright cmassengale Cnidocyte Coiled nematocyst copyright cmassengale
Barbed, threaded stinger copyright cmassengale Nematocyst Barbed, threaded stinger capsule’s lid trigger nematocyst copyright cmassengale 9
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copyright cmassengale Cnidarian Systems Have a simple nerve net & sensory receptors Muscles help in directional movement & capturing prey copyright cmassengale
Jellylike mesoglea between two cell layers supports cnidarian mesoglea-filled bell tentacles Jellylike mesoglea between two cell layers supports cnidarian copyright cmassengale 12
Two Main Body Plans of Cnidarians UPRIGHT TENTACLES TENTACLES HANG DOWN Polyp epidermis mouth mesoglea gastrodermis Medusa Mesoglea THICK Mesoglea THIN copyright cmassengale
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copyright cmassengale Cnidarian Diversity Scyphozoans: Jellyfish Anthozoans: Sea anemones Corals Hydrozoans: Hydra Cubozoa Box Jellies copyright cmassengale 15
copyright cmassengale Cnidarian Diversity Coral polyps Jellyfish Sea Anemone Coral polyps copyright cmassengale 16
copyright cmassengale Anthozoans copyright cmassengale
Anthozoan Characteristics Sea Anemones Brightly colored & Resemble flowers Solitary polyps Feed on invertebrates & fish Corals Most are colonial Build limestone case Live as polyps in their case copyright cmassengale
copyright cmassengale Sea Anemones & Coral ANEMONE CORAL copyright cmassengale 19
Distribution of Coral Reefs copyright cmassengale 20
copyright cmassengale Hydrozoans copyright cmassengale
copyright cmassengale Hydrozoans Hydra Exist only as polyps Reproduce by budding Freshwater only Form resistant zygotes when environment is bad Move by somersaulting with tentacles copyright cmassengale 22
copyright cmassengale (A) late Blastula, (B) sideview of early gastrula, (C) view on blastopore of gastrula, (D) planula larva, (E) primary polyp copyright cmassengale
copyright cmassengale Hydra copyright cmassengale 24
copyright cmassengale Hydra Feeding copyright cmassengale 25
Food in Gastrovascular Cavity copyright cmassengale
Portuguese man-of-war copyright cmassengale Colonial Hydrozoan (not a single organism) Tentacles sting prey such as fish & humans Polyps in colony feed Has gas-filled air float copyright cmassengale
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copyright cmassengale Hydrozoan Life Cycle Most hydrozoans alternate polyp and medusa forms, as in the life cycle of Obelia copyright cmassengale 29
Obelia Life Cycle (Hydrozoan) Larva called a planula female medusa male medusa reproductive polyp sperm ovum feeding polyp zygote polyp forming planula Fig. 25-15a, p.411 copyright cmassengale 30
copyright cmassengale Scyphozoans copyright cmassengale
Scyphozoan Characteristics Jellyfish Medusa is dominant body form Go through small polyp stage during life cycle Stinging tentacles May live close to shore or the open ocean
Parts of a Jellyfish 33 33
Some Jellyfish Show Luminescence 34 34
35 35
Jellyfish Life Cycle
copyright cmassengale CTENOPHORANS copyright cmassengale 37 37
Ctenophoran Characteristics Called comb jellies All marine Approximately 100 species May be spherical, ovoid, or elongate in appearance Bioluminescent copyright cmassengale
Ctenophoran Characteristics Radial symmetry Have eight plates of fused cilia that resemble combs Move by beating cilia Most of the body is jelly-like mesoglea Body & tentacles covered with sticky mucus to catch prey copyright cmassengale
copyright cmassengale Comb Jelly Anatomy copyright cmassengale 40
copyright cmassengale Tentacles Ctenophore: Comb Jelly copyright cmassengale 41
Ctenophore
Alive
46 46
copyright cmassengale Cubozoans Box JellyFish copyright cmassengale 47
The End