Chapter 33 - CR

Chapter 33 - CR - Chapter 33 Invertebrates Page 1 of 29...

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Page 1 of 29 Chapter 33 Chapter 33 Invertebrates
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Page 2 of 29 Overview: Life Without a Backbone Overview: Life Without a Backbone Invertebrates are animals that lack a backbone They account for 95% of known animal species Figure 33.1 Ancestral colonial choanoflagellate Eumetazoa Bilateria Deuterostomia Porifera Cnidaria Other bilaterians (including Nematoda, Arthropoda, Mollusca, and Annelida) Echinodermata Chordata Figure 33.2
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Page 3 of 29 33.1: Sponges, phylum Porifera 33.1: Sponges, phylum Porifera Sponges are sessile , have a porous body and choanocytes Live in both fresh and marine waters Lack true tissues and organs Sponges are suspension feeders capturing bacteria and food particles suspended in the water that passes through their body Choanocytes , flagellated collar cells, generate a water current through the sponge and ingest suspended food Most sponges are hermaphrodites Osculum Choanocyte Flagellum Porocytes
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Page 4 of 29 33.2: Jellies, Corals, and Hydras 33.2: Jellies, Corals, and Hydras Phylum: Cnidaria Phylum: Cnidaria Cnidarians are one of the oldest groups in the clade, Eumetazoa Cnidarians are diploblastic , have radial symmetry, and cnidocytes The basic body plan of a cnidarian is a sac with a central digestive compartment, the gastrovascular cavity (which may also be used as a hydrostatic skeleton) A single opening functions as both mouth and anus There are two variations on this body plan The sessile polyp and the floating medusa
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Page 5 of 29 Mouth/anus Tentacle Gastrovascular cavity Gastrodermis Mesoglea (jelly) Epidermis Tentacle Body stalk Mouth/anus Medusa Polyp Figure 33.5 Cnidarians are carnivores and use tentacles to capture prey The tentacles are armed with cnidocytes , unique cells that function in defense and the capture of prey Tentacle “Trigger” Nematocyst Coiled thread Discharge Of thread Cnidocyte Prey Figure 33.6
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Page 6 of 29 The phylum Cnidaria is divided into four The phylum Cnidaria is divided into four major classes: major classes: Hydrozoa, Hydrozoa, Scyphozoa, Scyphozoa, Cubozoa, Cubozoa, and Anthozoa and Anthozoa Table 33.1 These colonial polyps are members of (b) Many species of jellies (class Scyphozoa), including the species pictured here, are bioluminescent. The largest scyphozoans have tentacles more than 100 m long dangling from a bell-shaped (c) The sea wasp ( Chironex fleckeri ) is a member of class Cubozoa. Its poison, which can subdue fish and other large prey, is more potent than cobra venom. (d) Sea anemones and other members of class Anthozoa exist only as polyps.
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Page 7 of 29 33.3: Most animals have bilateral 33.3: Most animals have bilateral symmetry symmetry The vast majority of animal species belong to the clade Bilateria This clade consists of animals with bilateral symmetry and triploblastic development Flatworms Members of phylum Platyhelminthes Live in marine, freshwater, and damp terrestrial habitats
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Chapter 33 - CR - Chapter 33 Invertebrates Page 1 of 29...

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