zoology cnidaria

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    Phylum Cnidaria

    Common Name: None

    a.k.a.coelenterata

    Examples: Hydra, jellyfish, coral,

    Portuguese man of war, sea anemone

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    Phylum Cnidaria

    A. Gr. knide nettle) + L. aria, -like

    B. ny dar' e-a

    D. 9,000 species.

    E. Odd name = ph. Coelenterata, early 1900'sF. coelenterate = Cnidaria + Ctenophora

    G. Metazoans, have tissue but organs poorly defined

    H. Tentacles present, can be fused

    I. Mouth(=anus), digestive area = gastro-vasula cavity(GV)

    J. Body can have covering skeleton, 98% of body isK. Diploblastic ; 2 tissue layers(=ectoderm & endoderm) during

    gastrula stage

    L. In marine & fresh water

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    Cnidaria - Morphology and

    DigestionE. Radial or Biradial symmetry

    F. Gastrovascular cavity

    G. Most small; colonial organisms may be themost massive on Earth

    H. Tissue level of organization, a few organs

    I. Extracellular digestion in

    gastrovascular cavity intracellular ingastrodermal cells

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    Cnidaria Excretion, Nervous

    System & LocomotionJ. Simple excretion

    K. Simple respiration by diffusion

    L. Nerve cells and nerve netM. Sense organs (statocysts and ocelli)

    N. Some can swim by jet propulsion orthrough cilia

    O. Polymorphism in some species -medusa and polyp

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    Cnidaria Skeleton and Reproduction

    P. hydroskeleton or exoskeleton orendoskeleton

    Q. Reproduction can be sexual orasexual1. Asexual reproduction by budding in

    polyps

    2. Sexual reproduction by gametes in allmedusae, some polyps

    3. Sexual forms monecious or dioecious

    4. Planula larvae

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    Reproduction

    Hydra Warm: Asexual (budding)

    Dropping Temp triggers sexual

    Jellyfish Polyps are asexual

    Medusa are sexual

    Hermaphrodite Anemone, mostly

    Produce both egg and sperm

    fr.wikipedia.org

    www.dpo.uab.edu

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    Reproduction

    Individual Jellyfish are either male or female. The eggsand sperm develop in very colourful special areas called'Gonads' inside the body wall. When all of the eggs and

    sperm are fully developed, they are released into thestomach and then through the mouth into the sea. In mostcases, to reproduce, a male jellyfish releases his sperminto the surrounding water. The sperm then swims into themouth of the female jellyfish, allowing the fertilization of

    the ova process to begin. Moon jellies, however, use adifferent process: their eggs become lodged in pits on theoral arms, which form a temporary brood chamber toaccommodate fertilization.

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    Reproduction

    When the eggs are released into the sea they are

    fertilized by the sperm and continue to develop.As in all many-celled animals, the microscopicfertilized eggs begin a series of cell divisionswhich finally result in an embryo. However, theembryo does not develop directly into a baby

    jellyfish, but becomes a tiny, flattened creaturecalled a 'Planula'.

    The Planula, which is covered with rapidlybeating hairlike cilia (thin, tail-like projections), isable to swim and may be carried a considerabledistance by ocean currents during its shortswimming period, lasting from a few hours toseveral days. The tiny Planula then makes its waytoward the sea bottom where it actively looks fora suitable place to attach itself. At this point, aamazing series of events take place.

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    Reproduction

    The tiny Planula floating

    in the sea. Searching for a place toattach itself.

    Once attached, it feedson passing, floating food.

    At this stage, the Polypsmouth and tentacles are

    facing upwards. Grooves appear and

    become deeper,eventually cuttingthrough the Polyps body.

    A pile of disc-shaped

    structures emerge andbreak away. Each being ababy Jellyfish.

    At this stage it is called aMedusa and is theJellyfish form werecognise in our oceans.

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    Cnidaria - Ecology

    R. Mostly marine, some freshwater

    S. Mostly freeliving

    T. Feed by capture of prey;endosymbionts

    1. Cnidocytes - stinging cellscontaining nematocysts

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    Nutrition: sting prey with nematocysts,push food into mouth with tentacles.

    www.palaeos.com

    www.jcu.edu.au

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    The freshwater hydra is asimple organism with a basal

    suction disk or foot, and apicaltentacles.

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    Nematocyst

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    Cnidaria Evolution and

    TaxonomyU. Cnidarians from

    ancestral radially symmetrical

    planula larvaV. 4 Classes:

    1. Hydrozoa

    2. Scyphozoa

    3. Cubozoa

    4. Anthozoa (

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    Class Hydrozoa

    a) Gr. Hydra - water serpent + zoon, animalb) Hi-dro-zo'-a

    c) Dominated (in most) by the polyp form

    d) Mostly marine, mostly colonial

    e) 2,700 species

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    universe-review.ca

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    Class Scyphozoa

    Gr. skyphos, cup + zoon, animal

    Si-fo-zo'-a

    dominated (in most) by the medusa form(1) polyp (strobila) form

    free-swimming medusa

    some (Cassiopeia) with endosymbionts

    200 species

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    Cassiopeia, the upside-down

    jellyfish, harbors endosymbiontswhich photosynthesize. Laying

    upside-down in sunny areas bringslight to the endosymbionts.

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    Class Cubozoaa) Figure 13-20 (266)

    b) Gr. Kybos, cube +zoon, animal

    c) Ku' bo-zo' ad) dominated (in most) by

    the medusa form

    e) about 100 species

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    Class Anthozoa

    Gr. Anthos, flower, zoon, animal

    An-tho-zo' a

    all polyps - no medusae all marine

    6000 species

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    3 main groups of

    anthozoans:(1) Sea anemones and hard

    corals

    (2) tube anemones and thornycorals

    (3) soft corals, horny corals, sea

    fans, sea pens, sea pansies

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    Anenomes are exclusivelymarine, as are all anthozoans.

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    Rather than stinging, sunanenomes stick to their prey.

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    It is obvious as to how braincoral got its name.

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    Here is a young braincoral. These coloniescan build for thousands

    of years.

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    Other organisms, such as theseChristmas Tree worms, maketheur home in or on the coral.

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    Corals compete for light just theway plants do on land.

    This is Elkhorn Coral.

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    Here a damselfish hides among thebranches of fire coral. Fire coralhas tiny spines which irritate the

    skin, much as a stinging nettle does.

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    Soft corals such asdead-mans fingers can

    bend with waves andcurrents.

    This is another soft coral.

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    Sea fans are also anthozoansalong with sea anenomes, hardcorals, tube anenomes, thorny

    corals, soft corals, sea pensand sea pansies.

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    "Why do evolutionary biologists care who's related to whom, and how do scientists find out how different

    animals are related?"

    http://www.ucmp.berkeley.edu/phyla/Phyla2001.maphttp://www.ucmp.berkeley.edu/phyla/Phyla2001.maphttp://www.ucmp.berkeley.edu/phyla/Phyla2001.map
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    Scientists care because phylogeny is the fundamental product of evolution.Therefore, a phylogenetic hypothesis is essential if you want to understandbiological phenomena, most of which have an evolutionary explanation.

    Since many scientists would like to know how animal diversity and animalbody plans came to be, presently there is a great deal of work on resolvingthe evolutionary relationships among the major groups of animals. Much ofthis research has relied upon morphological characters, especially thoseexpressed in early development (e.g. embryological characters). Morerecently, a significant advance in our understanding of animal phylogeny

    has been brought about by the study of molecules (in particular genes andtheir protein products) contained within animal cells. The phylogenypresented here is a relatively conservative guess based upon variouspublished studies of 18S ribosomal RNA sequence data. As you can see,there are quite a few unresolved branches, and therefore a great deal ofwork to be done in this area.

    Note that the phylum Porifera (the sponges) is paraphyletic. A few lines ofindependent evidence suggest that one group of sponges is actually moreclosely related to non-sponge animals than it is to the other sponges. Thisis an important finding for it implies that the lineage leading to all otheranimals (including ourseleves!) was directly descended from an animal witha sponge body and a sponge life style.

    http://evolution.berkeley.edu/evolibrary/article/evo_03http://www.ucmp.berkeley.edu/clad/clad4.htmlhttp://www.ucmp.berkeley.edu/porifera/porifera.htmlhttp://www.ucmp.berkeley.edu/glossary/gloss1phylo.htmlhttp://www.ucmp.berkeley.edu/glossary/gloss1phylo.htmlhttp://www.ucmp.berkeley.edu/porifera/porifera.htmlhttp://www.ucmp.berkeley.edu/clad/clad4.htmlhttp://www.ucmp.berkeley.edu/clad/clad4.htmlhttp://www.ucmp.berkeley.edu/clad/clad4.htmlhttp://evolution.berkeley.edu/evolibrary/article/evo_03http://evolution.berkeley.edu/evolibrary/article/evo_03http://evolution.berkeley.edu/evolibrary/article/evo_03http://evolution.berkeley.edu/evolibrary/article/evo_03http://evolution.berkeley.edu/evolibrary/article/evo_03http://evolution.berkeley.edu/evolibrary/article/evo_03http://evolution.berkeley.edu/evolibrary/article/evo_03http://evolution.berkeley.edu/evolibrary/article/evo_03http://evolution.berkeley.edu/evolibrary/article/evo_03http://evolution.berkeley.edu/evolibrary/article/evo_03http://evolution.berkeley.edu/evolibrary/article/evo_03http://evolution.berkeley.edu/evolibrary/article/evo_03http://evolution.berkeley.edu/evolibrary/article/evo_03