BIOL211#10and#11

BIOL211#10and#11 - Chapter 33 Invertebrates are animals...

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1 Chapter 33 The Invertebrates Invertebrates are animals that lack a backbone Account for 95% of all known animal species Figure 33.1 Eumetazoa – Animals that have true tissues Parazoa – Animals that lack specialized (true) tissues – Porifera (sponges) Parazoa Phylum Porifera (sponges) – Multicellular and possess several different types of cells – Asymmetrical – Adults are sessile; larvae are free-swimming – Live in both fresh and marine waters Sponges are suspension feeders Figure 33.2
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2 Sponges – Most sponges are hermaphrodites – Most exhibit sequential hermaphroditism – Eggs remain in the mesohyl; sperm are carried out of the sponge by water currents – Zygotes develop into flagellated, swimming larvae that disperse from the parent sponge Radiata: Jellyfish and Others Phylum Cnidaria (cnidarians) – Include hydras, jellyfish, box jellies, sea anemones, and corals Phylum Ctenophora (ctenophores) – Comb jellies Both occur mainly in marine habitats, although a few are freshwater species Cnidarians and Ctenophores – Basic body plan is a sac with a central digestive compartment known as the gastrovascular cavity – A single opening functions as both mouth and anus Two variations of the body plan Figure 33.3 Cnidarians may exist in both polyp and medusa forms Figure 33.4 Cnidarians are carnivores that use tentacles armed with cnidocytes to capture prey Figure 33.5
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3 Four main classes of cnidarians Cnidarians Scyphozoa Hydrozoa Anthozoa Cubozoa Ctenophores – Have 8 rows of cilia on their surface – Largest animals to use cilia for locomotion – Lack stinging cells – All live in marine environments – Hermaphroditic – Nearly all exhibit bioluminescence Ctenophore (comb jelly) Figure 33.6 Lophotrochozoa Phylum Platyhelminthes – Flatworms – Lack specialized respiratory or circulatory systems to transport gases – Lack a true body cavity (acoelomates) – Have an incomplete digestive system – Thin bodies; flattened dorsoventrally
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4 Flatworms Figure 33.7 Flatworms – Live in marine, freshwater, and damp terrestrial habitats – Most are hermaphroditic but do not fertilize their own eggs – Can also reproduce asexually by splitting into two parts – Include many parasitic species Four classes Most turbellarians are free-living and marine The best known freshwater turbellarians are called planarians Monogeneans and trematodes live as parasites in or on other animals Most monogeneans are parasites of fish Trematodes parasitize a wide range of hosts
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5 Trematodes (Chinese liver fluke) Figure 33.9 Trematodes (blood fluke) Mature Flukes Fluke Egg Cestodes (tapeworms) Phylum Rotifera – Rotifers – Inhabit freshwater, marine, and damp soil habitats Figure 33.10 Rotifers – Have an alimentary canal with a separate mouth and anus – Some reproduce by parthenogenesis
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This note was uploaded on 10/02/2011 for the course BIOL 211 taught by Professor Boury during the Spring '08 term at Iowa State.

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BIOL211#10and#11 - Chapter 33 Invertebrates are animals...

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