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1500_8_ArthropodClassification - BIO1500 W07 Arthopoda...

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Unformatted text preview: BIO1500 W07 Arthopoda: Classification The phylum Arthropoda is either closely related to nematodes: Ecdysozoa hypothesis Ecdysozoa: Nematodes + Arthropods Raven Fig. 32.2 Or to Annelids: Articulata hypothesis Articulata Articulata: Annelids + Arthropods Raven Fig. 32.2 Arthropods basic facts !~1,000,000 species -> largest animal phylum !Jointed appendages !Size range from 80µm to up to 3.6m !Primitively marine but explored freshwater and terrestrial habitats !Include parasites, pests and beneficial species !Cuticle based exoskeleton !Growth requires molting Defining external body plan traits of Arthropoda !Jointed appendages ! Exoskeleton !True segmentation !Organisation of longitudinal body plan into tagmata: head, thorax, trunk, abdomen Myriapoda Chelicerata Crustacea Hexapoda Arthropoda represent the largest animal phylum Mollusca Chordata Arthropoda Platyhelminthes Nematoda (?) Porifera Annelida Echinodermata Sarcomastigophora Apicomplex Ciliophora ~1,000,000 Arthropoda includes four subphyla: Crustacea, Hexapoda, Myriapoda, Chelicerata Crustacea Hexapoda Myriapoda Chelicerata Pancrustacea Subphylum CHELICERATA: defining morphological traits Defined head region missing Body divided in prosoma and opisthosoma Pincer fangs (chelicereae), as the most anterior appendages. 4 pairs of legs Tagmosis in Chelicerates Prosoma Ophisthosoma Chelicera and pedipalps Chelicerae Pedipalp Walking legs Subphylum CHELICERATA: classification Subphylum 1) Xiphosura (Horseshoe crabs) 2) Pycnogonida (sea spiders) 2) (sea 3) Arachnida (several orders): 3) Arachnida Scorpions Spiders (Araneae) Ticks Mites Pseudoscorpions Daddy-long-legs Arachnida" from Ernst Haeckel's Kunstformen der Natur, 1904 Xiphosura Pycnogonida: Sea spiders Arachnida Arachnida pseudoscorpions Arachnida mite mite Arachnida Peacock mite, Tuckerella sp.jpg Arachnida Arachnida Araneae Araneae Subphylum MYRIAPODA: defining morphological traits Pronounced head region First appendage is antenna Body divided in head and trunk tagmata Mandible major mouth appendage functioning as jaw Multilegged Comparison of arthropod head segment organization Comparison Damen et al 1998 Subphylum MYRIAPODA: classification 1) Diplopoda (herbivorous) 2) Chilopoda (carnivorous) 3) Pauropoda (root hairs, fungi) 4) Symphyla (herbivorous and detritus feeders) Pauropoda Symphyla Subphylum CRUSTACEA: defining morphological traits Defined head region (can be fused with throrax into cephalothorax) Two pairs of antennae Appendages (including antennae) biramous (branched) Nauplius larva Antennule Antenna Subphylum CRUSTACEA: classification Subphylum 1) Branchiopoda 2) Remipedia 3) Cephalocarida 4) Maxillopoda 5) Ostracoda 6) Malacostraca Branchiopoda: primitive freshwater crustaceans Branchiopoda: Triops longicaudatus Photograph taken by Dominik Tomaszewski from http://mytriops.com/. Free use obtained by en:User:Quatermass. Remipedia: primitive marine cave crustaceans Dorsal view of a remipede from the Bahamas. Photo courtesy of Thomas Iliffe (Texas A&M). http://www.ucmp.berkeley.edu/arthropoda/crustac ea/remipedia.html Cephalocarida: horse shoe shrimps, only 9 species Cephalocarida: Maxillopoda: characterized by reduced appendages and abdomen, includes barnacles and copepods Copepod Ostracoda: seed shrimp, small crustaceans protected by Ostracoda: chitinous or calcareous shell Malacostraca: includes crabs, lobster, shrimp, mantis shrimps and krill crab krill shrimp woodlouse lobster Subphylum HEXAPODA: classification 350,000 125,000 120,000 150,000 SESSILE as adults! SESSILE Hennig, 1953 350,000 125,000 120,000 150,000 SESSILE as adults! Hennig, 1953 Subphylum HEXAPODA: current classification of 33 orders Subphylum Different forms of postembryonic insect development Holometabola Hemimetabola Ametabola Subphylum Hexapoda: defining morphological traits Subphylum 1) Three tagmata: head, thorax, abdomen 2) Thorax continaing three segments 3) Three pairs of walking appendages 4) Three gnathal mouthparts: mandible, maxilla, labium 5) One pair of antennae Comparison of arthropod head segment organization Damen et al 1998 ...
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  • Winter '08
  • Pandolfi
  • Subphylum Myriapoda, Subphylum Hexapoda, Subphylum Chelicerata, Subphylum Crustacea, Myriapoda Chelicerata Crustacea Hexapoda

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