17. Artrhopoda II Oct 28

17. Artrhopoda II Oct 28 - Phylum Arthropoda Phylum...

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1 Phylum Phylum Arthropoda Arthropoda Triploblastic Triploblastic Coelomate Protostomes greatest # species described huge diversity of life styles, body structures, and morphologies Taxonomy in constant flux, confusing large number of subphyla, classes, etc. here it is important to know TAXA, HIERARCHY OF TAXA, rather than taxonomy (names of level) The exam will cover : Phylum Arthropoda Trilobitomorpha Trilobita Chelicerata Xiphosura Arachnida Pycnogonida Mandibulata Crustacea ~10 Classes Tracheata Hexapoda Myriapoda Chilopoda Diplopoda Plus others Exoskeleton Exoskeleton hardened cuticle with chitin, tanned proteins, CaCO 3 Covers entire body including anterior and posterior gut, gastric mill, etc. Jointed appendages Flexible joints Flexible joints body parts that move Segmented Paired Appendages in each segment ventral nerve cord - segmental ganglia
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2 Specialization of segments and segmental appendages Tagmatization Fusion of segments into functional units = Tagma e.g., Insect: head, thorax, abdomen Crustacean: cephalothorax, abdomen Spider: prosoma, opisthosoma Open Circulatory system Haemocoel – major body cavity major body cavity Coelom reduced (small areas around reproductive and excretory system) Very good at detecting motion Compound Eyes Image forming Reproduction Non-motile sperm Spermatophores – packets of sperm Copulate Eggs usually brooded Development - direct indirect Today: Phylum Arthropoda Trilobitomorpha Cheliceraformes Chelicerata Xiphosura Arachnida Pycnogonida Crustacea ~10 Major Taxa Hexapoda Insecta Myriapoda
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3 Crustacea Crustacea ~ 10 Classes/ major groups ~ 10 Classes/ major groups Most marine Some freshwater Few make transition to living on land – many still tied to water for larval stages Crustacea crabs, lobsters, shrimp, barnacles, copepods Tagmata Head, thorax, abdomen Head - 5 pr. Appendages - First Antennae Second Antennae Mandibles First Maxillae Second Maxillae Thorax - 8 pr. Appendages specializations - food sorting - maxillipeds locomotion - pereopods Carapace - fused cover of head and thorax Cephalothorax - single tagma Abdominal Appendages Pleopods (pleon = abdomen) Some have distinct Uropods last few segments Terminal Telson with anus Can have appendages - caudal rami
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4 Crustacean Biramous Appendage 2 branches Endopodite - near midline Exopodite - lateral branch some modified in derived groups Molting: Must molt to grow When molting - body size inflated to create bigger
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17. Artrhopoda II Oct 28 - Phylum Arthropoda Phylum...

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