2. Invertebrates post

2. Invertebrates post - Invertebrates Phylogenetic Tree...

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Invertebrates
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Phylogenetic Tree Invertebrates Animals without backbone 95%
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Parazoa Animals without “true” tissue Cell layers are loose federations of cells Not true tissues (i.e. no specialization into muscle or nervous tissue) Individual cells can sense and react to changes in environment Sponges
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Body Plan Sac perforated with holes (Ostia) Spongocoel (central cavity) Osculum (exit) Suspension feeders Collect food from water Choanocytes (collar cells) • Spongocoel • Flagellated Generates water current • Collar (membrane around the base of the flagellum) – Traps food particles Ingestion via phagocytosis
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Body Plan Two layers of cells separated by mesohyl Amoebocytes reside in mesophyl Functions – Receive food from choanocytes, digest it, and distribution – Form skeletal fibers » Spicules (Ca++ carbonate or silica) » Flexible collagen based fibers (commercial use)
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Reproduction Hermaphrodites Gametes from choanocytes or amoebocytes Eggs reside in mesohyl Sperm carried out by water currents Zygote develops into flagellated swimming larvae Regeneration and/or asexual reproduction
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Radiata All other animals are Eumetazoans (True tissues) Radiata Radial symmetry Diploblastic embryos Phyla Cnidaria Ctenophora
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Phylum Cnidaria – Body Plan Members Hydras, Jellies, Sea Anemones, and Coral Animals Body plan Sac with central digestive cavity • Gastrovascular cavity • Single opening (mouth and anus) Types Polyps • Sessile Tentacles are used for food collection Medusa • Moves freely in water Some Cnidarians are both at different stages during life cycle
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Phylum Cnidaria – Food Acquisition Carnivores Batch reactor Tentacles around mouth captures prey and push food into the gastrovascular cavity Cnidocytes Unique cells on tentacle Immobilize prey Defense Nematocysts are the “stinging” capsules
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Phylum Cnidaria – Sensory and Movement True muscle is derived from the mesoderm Bundle of microfilaments arranged into contractile fibers Movements are coordinated by a Nerve Net i.e. No brain
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Phylum Cnidaria - Classes Three major classes Hydrozoa Alternate between polyp and medusa form Exception is the hydra (polyp only) Scyphozoa Medusa is dominant form Anthozoa Polyp is dominant form
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Protostomes Bilateral animals Protostomes Lophotrochozoa Platyhelminthes Rotifera Lophophorate Nemertea Mollusca Annelida Ecdysozoa Deuterostomes
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Phylum Platyhelminthes Acoelomate flatworms 20,000 different species Microscopic to 60 foot tapworms Bilateral Triploblastic (mesoderm) Contributes to more complex organ systems Food acquisition Gastrovascular cavity Tapeworms absorb nutrients Classes Turbellaria Monogenea Trematoda Cestoidea
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2. Invertebrates post - Invertebrates Phylogenetic Tree...

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