copyright cmassengale Cnidarians copyright cmassengale 1
copyright cmassengale
copyright cmassengale
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 4
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 5
Two Main Body Plans of Cnidarians UPRIGHT TENTACLES TENTACLES HANG DOWN Polyp epidermis mouth mesoglea gastrodermis Medusa Mesoglea THICK Mesoglea THIN copyright cmassengale
Medusa –(snakes for hair) In Greek mythology she was a female monster, gazing upon her could turn someone to stone. She was beheaded by Perseus who used her head as a weapon.
copyright cmassengale 8
Cnidarian Characteristics 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 9
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 10
Extracellular Digestion Food digested outside of cells copyright cmassengale 11
copyright cmassengale Cnidocyte Coiled nematocyst copyright cmassengale
Barbed, threaded stinger copyright cmassengale Nematocyst Barbed, threaded stinger capsule’s lid trigger nematocyst copyright cmassengale 13
copyright cmassengale 14
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 16
copyright cmassengale Cnidarian Diversity Coral polyps Jellyfish Sea Anemone Coral polyps copyright cmassengale 17
copyright cmassengale Cnidarian Diversity Scyphozoans: Jellyfish Anthozoans: Sea anemones Corals Hydrozoans: Hydra Portuguese Man-of-War copyright cmassengale 18
copyright cmassengale
copyright cmassengale Anthozoans copyright cmassengale
Anthozoan Characteristics Ex. Sea Anemones Brightly colored and resemble flowers Only live as solitary polyp Feed on invertebrates and fish And photosynthetic symbionts. Clownfish live in anemone tentacles (type of symbiosis?) copyright cmassengale
Anthozoan “flower animal” Ex. Corals Individual polyps that live in colonies. Motile larva Secretes a limestone case which build up & form reefs Live as polyps in their case CORAL copyright cmassengale 22
copyright cmassengale
Distribution of Coral Reefs copyright cmassengale 24
copyright cmassengale Hydrozoans copyright cmassengale
copyright cmassengale Hydrozoans Ex. Hydra Exist only as polyps Reproduce by budding Found only in freshwater Form resistant zygotes when environment is bad Move by somersaulting with tentacle copyright cmassengale 26
copyright cmassengale Hydra copyright cmassengale 27
copyright cmassengale Hydra Feeding copyright cmassengale 28
Food in Gastrovascular Cavity copyright cmassengale
Portuguese man-of-war copyright cmassengale Colonial Hydrozoan (a group of polyps living together) Tentacles sting prey such as fish & humans Each polyp has a job. 1.Produces tentacles to capture food. 2. Make gas-filled air float 3. Make sperm/eggs copyright cmassengale
copyright cmassengale 31 31
copyright cmassengale Scyphozoans copyright cmassengale
copyright cmassengale
copyright cmassengale
copyright cmassengale
copyright cmassengale
Scyphozoan “cup animals” Ex. Jellyfish Medusa is dominant body form Go through small polyp stage during life cycle. Reproduce using both asexual and sexual cycles Stinging tentacles 4m-30meters long May live close to shore or the open ocean
Parts of a Jellyfish 38 38
Some Jellyfish Show Bioluminescence 39 39
42 42
copyright cmassengale Hydrozoan Life Cycle Most hydrozoans alternate polyp and medusa forms, as in the life cycle of Obelia copyright cmassengale 43
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 44
Jellyfish Life Cycle