copyright cmassengale Cnidarians 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
copyright cmassengale 10
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
copyright cmassengale 14
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
More Cnidarians Brain Coral Red jellyfish copyright cmassengale
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 Exist only as Polyps Clownfish live in anemone tentacles Corals build a limestone case which build up & form reefs ANEMONE CORAL copyright cmassengale 20
Distribution of Coral Reefs copyright cmassengale 22
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 24
copyright cmassengale Hydra copyright cmassengale 25
copyright cmassengale Hydra Feeding copyright cmassengale 26
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
copyright cmassengale 29 29
Portuguese Man of War - cnidarian that floats in the water and has long tentacles
copyright cmassengale Hydrozoan Life Cycle Most hydrozoans alternate polyp and medusa forms, as in the life cycle of Obelia copyright cmassengale 32
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 33
copyright cmassengale Cubozoans Box JellyFish copyright cmassengale 34
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 37 37
Some Jellyfish Show Luminescence 38 38
39 39
Jellyfish Life Cycle
41 41
Multimedia Sponge Images and Videos - http://www.junglewalk.com/video/Sponge-movie.htm Cnidarian Images and Videos - http://www.junglewalk.com/video/Coelantrate-movie.htm General Invertebrate Movies at National Geographic --- really good video on the portuguese man of war (under invertebrates) Hydra Video at http://www.schooltube.com/video/55045/Hydra