docRecent Aedvances in Cephalopod Systematics
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Recent Aedvances in Cephalopod Systematics
Recent Aedvances in Cephalopod Systematics Kotaro TSUCHIYA Lab. Invertebrate Zoology What’ the Cephalopoda Squid landing in Japan� Cephalopod evolution� Paleozoic Mesozoic Million yr Neozoic Cephalopods � Squid Cuttlefish Vampire squid Octopus Bobtil squid Molluscan Characters� Current Classification of Mollusca� Phylum Mollusca Class Solenogastres Class Caudofoveata Eumollusca Class Polyplacophora Conchifera Class Monoplacophora Ganglioneura Viscelloconcha Class Gastropoda Class Cephalopoda Diasoma Class Scaphopoda Class Bivalvia Sister Group of Cephalopoda� Gastropoda Viscelloconcha Bivalvia Diasoma Scaphopoda Cephalopoda Cephalopod Characteristic A funnel derived from the molluscan foot or the molluscan neck region (Shigeno et al., 2007). Circumoral arms that are derived from the molluscan head (J.Z. Young, 1965) or the molluscan foot (Shigeno et al., 2007). Chitinous beaks. Image-forming eyes. Cephalopod Characteristic A funnel derived from the molluscan foot or the molluscan neck region (Shigeno et al., 2007). Cephalopod Characteristic Circumoral arms that are derived from the molluscan head (J.Z. Young, 1965) or the molluscan foot (Shigeno et al., 2007). Cephalopod Characteristic Chitinous beaks. Upper beak Buccal mass Cephalopod Characteristic Image-forming eyes. Ontogeny & Phylogeny Spiral cleavage - Discoidal cleavage Larval development - Direct development → Lecithophora or Meloblastea Fischer, 1880 As Subphylum for CEPHALOPODA trochophore Gastropoda veliger Cephalopoda Squid and Octopus Decapodiformes and Octopodiformes� What’s difference? Sucker morphology Buccal rappet existence Squid and Octopus What’s difference? Modification of the fourth pair of arms as tentacles� Current Classification of Cephalopoda Based on morphological character Octopus share what?� Octopodiformes (over 200spp.)� Octopoda Leach, 1818 Cirrata Grimpe, 1916 Incirrata Grimpe, 1916 Vampyromorpha Robson, 1929 Octopus share what?� Octopodiformes (over 200spp.)� True arms II modified or absent Horny rings in suckers absent� Buccal crown absent� Morecular Analysis� (Takumiya et al. 2006)� 16s rDNA 12s rDNA CO I Morecular Analysis� (Yokobori et al. 2007)� Mitochondria genome structure Current Classification of Decapodiformes� Clarke (1988) Morphological base “Order Teuthoidea” Divergent group in genus level 28 Families 71Genera Most of the families are oceanic, mesopelagic Oegopsida - Myopsida Presence or absence of Cornea � closed eye or open eye � Coastal or Oceanic� Family Chtenipterygidae - comb-fin squid with suckers on the buccal membrane. without carpal locking-apparatus on tentacles. with branchial canals in gills. Family Idiosepiidae - pygmy squid Gladius (shell) rudimental but present with an adhesive organ on the dorsal surface of the mantle Idiosepius pygmaeus (6-8mm ML) � Family Australiteuthidae Lu, 2005 Myopsid eye Spritted fins Feather-shaped chitinous gladius Australiteuthis aldrichi Lu, 2005 (<30mm ML) Morphological comparisons of the major taxa within the Decapodiformes Oegopsida Bathyteuthoidea Myopsida Idiosepiidae Spirulidae Sepioidea Cornea canal Branchial Buccal support circular sucker Sucker pocket muscle Tentacle Interstellate connective No No Yes Yes Yes No No Yes No No Yes/No No No Yes/No No Yes Yes Yes No Yes Yes No Yes Yes No No No Yes Yes Yes ? Yes Yes Yes No No Recent Systematic Hypothesis ����������ー Molecular base Morecular Analysis (Akasaki et al. 2006)� mtDNA genome structure Hypothesis from Morecular Analysis (Akasaki et al. 2006) � mtDNA genome structure Hypothesis from Morphological and Molecular complex Analysis result� 101 morphological characters mt cytochrom c oxydase subunit I ; nuclear 18S rDNA; D3 expansion fragment of 28S rDNA, Histon H3 � Classification Updated Young (2008) �Species-level Taxonomy Only 700 species are known from World Ocean Cryptic Speciation Coastal species (Loliginids, Sepiids) Western Australia Triantafillos et al. (2005) Japan Izuka et al. (1996) Sepioteuthis lessoniana Deep-sea Squids - still unexplored field Nektonic species - net avoidance Difficult to catch adult specimens by sampling gear Still unkown the mature, largest size in most of deep-sea species Life cycle, life history Octopus - Labyrinth of Taxonomy Scarce of hard tissue in octopus body Absence of stable key taxonomic character Need to evaluate useful taxonomical information from living animals