Introduction to the CHORDATES
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Flatworms Phylum Platyhelminthes
Flatworms Phylum Platyhelminthes The flatworms include more than 13,000 species of free-living and parasitic species.There are 3 classes of flat- worms, the planarians, flukes and tapeworms. General Physical Traits (Anatomy): Flatworms are bilaterally symmetrical. This means that they can only be cut them length-wise to produce two mirror-image halves. They have a distinct right and left half. This is differ- ent from radially symmetrical animals, like the anemones, which can be cut anywhere top to bottom to get two similar halves. Flatworms have 3 tissue layers, compared to the 2 layers in sponges and cnidarians (jellyfishes, anemones and corals). They also have only one opening for food to enter and waste to leave, like the sponges and cnidarians. This is called a “sac” body plan. Planarian (class Tubellaria) Habitat: They live mostly in saltwater (marine) habitats, but are also found in freshwater. Habits: They are free-living flatworms (not parasites). Physical Traits (Anatomy): Planarians are small - less than a centimeter long. They have a head, brain and sense organs. This is called “cephalization.” The sense organs – called eyespots – look like eyes and are sensitive to light changes, but are not like human eyes. They are made up of simple nerve cells that respond to stimuli, like light. When many nerve cells are gathered in one place, they are called a “ganglion,” so the two eyespots are actually ganglia. They also have points on either side of the head that look a bit like ears, called “sensory lobes” or auricles. They do not hear, but can sense food. -
"Lophophorates" Brachiopoda Echinodermata Asterozoa
Deuterostomes Bryozoa Phoronida "lophophorates" Brachiopoda Echinodermata Asterozoa Stelleroidea Asteroidea Ophiuroidea Echinozoa Holothuroidea Echinoidea Crinozoa Crinoidea Chaetognatha (arrow worms) Hemichordata (acorn worms) Chordata Urochordata (sea squirt) Cephalochordata (amphioxoius) Vertebrata PHYLUM CHAETOGNATHA (70 spp) Arrow worms Fossils from the Cambrium Carnivorous - link between small phytoplankton and larger zooplankton (1-15 cm long) Pharyngeal gill pores No notochord Peculiar origin for mesoderm (not strictly enterocoelous) Uncertain relationship with echinoderms PHYLUM HEMICHORDATA (120 spp) Acorn worms Pharyngeal gill pores No notochord (Stomochord cartilaginous and once thought homologous w/notochord) Tornaria larvae very similar to asteroidea Bipinnaria larvae CLASS ENTEROPNEUSTA (acorn worms) Marine, bottom dwellers CLASS PTEROBRANCHIA Colonial, sessile, filter feeding, tube dwellers Small (1-2 mm), "U" shaped gut, no gill slits PHYLUM CHORDATA Body segmented Axial notochord Dorsal hollow nerve chord Paired gill slits Post anal tail SUBPHYLUM UROCHORDATA Marine, sessile Body covered in a cellulose tunic ("Tunicates") Filter feeder (» 200 L/day) - perforated pharnx adapted for filtering & repiration Pharyngeal basket contractable - squirts water when exposed at low tide Hermaphrodites Tadpole larvae w/chordate characteristics (neoteny) CLASS ASCIDIACEA (sea squirt/tunicate - sessile) No excretory system Open circulatory system (can reverse blood flow) Endostyle - (homologous to thyroid of vertebrates) ciliated groove -
Evidence for Selection on a Chordate Histocompatibility Locus
ORIGINAL ARTICLE doi:10.1111/j.1558-5646.2012.01787.x EVIDENCE FOR SELECTION ON A CHORDATE HISTOCOMPATIBILITY LOCUS Marie L. Nydam,1,2,3 Alyssa A. Taylor,3 and Anthony W. De Tomaso3 1Division of Science and Mathematics, Centre College, Danville, Kentucky 40422 2E-mail: [email protected] 3Department of Molecular, Cellular, and Developmental Biology, University of California Santa Barbara, Santa Barbara, California 93106 Received June 7, 2011 Accepted July 31, 2012 Allorecognition is the ability of an organism to differentiate self or close relatives from unrelated individuals. The best known applications of allorecognition are the prevention of inbreeding in hermaphroditic species (e.g., the self-incompatibility [SI] systems in plants), the vertebrate immune response to foreign antigens mediated by MHC loci, and somatic fusion, where two genetically independent individuals physically join to become a chimera. In the few model systems where the loci governing allorecognition outcomes have been identified, the corresponding proteins have exhibited exceptional polymorphism. But information about the evolution of this polymorphism outside MHC is limited. We address this subject in the ascidian Botryllus schlosseri,where allorecognition outcomes are determined by a single locus, called FuHC (Fusion/HistoCompatibility). Molecular variation in FuHC is distributed almost entirely within populations, with very little evidence for differentiation among different populations. Mutation plays a larger role than recombination in the creation of FuHC polymorphism. A selection statistic, neutrality tests, and distribution of variation within and among different populations all provide evidence for selection acting on FuHC, but are not in agreement as to whether the selection is balancing or directional. -
Brains of Primitive Chordates 439
Brains of Primitive Chordates 439 Brains of Primitive Chordates J C Glover, University of Oslo, Oslo, Norway although providing a more direct link to the evolu- B Fritzsch, Creighton University, Omaha, NE, USA tionary clock, is nevertheless hampered by differing ã 2009 Elsevier Ltd. All rights reserved. rates of evolution, both among species and among genes, and a still largely deficient fossil record. Until recently, it was widely accepted, both on morpholog- ical and molecular grounds, that cephalochordates Introduction and craniates were sister taxons, with urochordates Craniates (which include the sister taxa vertebrata being more distant craniate relatives and with hemi- and hyperotreti, or hagfishes) represent the most chordates being more closely related to echinoderms complex organisms in the chordate phylum, particu- (Figure 1(a)). The molecular data only weakly sup- larly with respect to the organization and function of ported a coherent chordate taxon, however, indicat- the central nervous system. How brain complexity ing that apparent morphological similarities among has arisen during evolution is one of the most chordates are imposed on deep divisions among the fascinating questions facing modern science, and it extant deuterostome taxa. Recent analysis of a sub- speaks directly to the more philosophical question stantially larger number of genes has reversed the of what makes us human. Considerable interest has positions of cephalochordates and urochordates, pro- therefore been directed toward understanding the moting the latter to the most closely related craniate genetic and developmental underpinnings of nervous relatives (Figure 1(b)). system organization in our more ‘primitive’ chordate relatives, in the search for the origins of the vertebrate Comparative Appearance of Brains, brain in a common chordate ancestor. -
Intestinal Helminths of the White Sucker, Catostomus Commersoni (Lacepede), in SE Wisconsin
OF WASHINGTON, VOLUME 41, NUMBER 1, JANUARY 1974 81 Intestinal Helminths of the White Sucker, Catostomus commersoni (Lacepede), in SE Wisconsin OMAR M. AMIN Science Division, University of Wisconsin-Parkside, Kenosha 53140 ABSTRACT: Five species of helminths were recovered from the intestine of the white sucker, Catostomus commersoni (Lacepede), in southeastern Wisconsin. Hosts were seined in five sites in both the Root River (Milwaukee and Racine counties; autumn 1971) and the Pike River (Racine and Kenosha counties; autumn 1972). The helminths are Triganodistomum attenuatum Mueller and Van Cleave, 1932 (Trem- atoda: Lissorchiidae), new locality record; Eiacetabulum macrocephalum McCrae, 1962 (Cestoda: Caryophyllaeidae), new state record; Biacetabulum biloculoides Mackiewicz and McCrae, 1965 (Cestoda: Caryophyllaeidae), new state record; Acanthocephahis dims (Van Cleave, 1931) Van Cleave and Townsend, 1936, new host and state record; Dorylaimtis sp. (?) Dujardin, 1845 (Nematoda: Dory- laimidae), a nonparasitie nematode reported for the first time in this fish. Distribution, structural obser- vations, and host-parasite relationships of the above species are discussed. Previous reports of fish parasites in Wis- upon recovery were placed in 70% alcohol. consin were confined to the geographical Hosts were classed in one of three size classes northeast and west (Pearse, 1924a), north according to their total length, 5-9.9, 10-14.9, (Bangham, 1946), northwest (Fischthal, 1947, and 15-37 cm. 1950, 1952), and east (Anthony, 1963). These Trematodes and cestodes were stained in reports dealt only with host records. Literature Semichon's carmine, cleared in xylene, and on the ecology or host-parasite relationship of whole-mounted in Canada balsam. Acantho- fish parasites in Wisconsin is relatively scarce cephalans were fixed in Bouin's fluid, stained (Marshall and Gilbert, 1905; Pearse, 1924b; in Harris' hematoxylin, cleared in beechwood Cross, 1938). -
(Nematoda: Thelazioidea) in the Blue Sucker, Cycleptus Elongatus (Lesueur, 1817), from Illinois
Transactions of the Illinois State Academy of Science received 12/10/01 (2002), Volume 95, #2, pp. 107 - 109 accepted 2/22/02 First Record of Rhabdochona cascadilla Wigdor, 1918 (Nematoda: Thelazioidea) in the Blue Sucker, Cycleptus elongatus (Lesueur, 1817), from Illinois William G. Dyer and William J. Poly Department of Zoology Southern Illinois University Carbondale, Illinois 62901-6501 ABSTRACT Rhabdochona cascadilla was detected in the intestine of Cycleptus elongatus from the Mississippi River in Randolph County, Illinois. This constitutes the first record of this rhabdochonid nematode in the blue sucker and the only internal helminth for this host. INTRODUCTION Nematodes of the genus Rhabdochona Railliet, 1916 (Thelazioidea, Rhabdochonidae) are cosmopolitan in distribution as intestinal parasites of freshwater fishes (Moravec and Coy Otero, 1987; Moravec, 1994). Approximately 96 nominal species have been recognized of which 19 have been reported from North and South America (see Sanchez-Alvarez et al., 1998). Of rhabdochonid nematodes reported from North America, Rhabdochona cascadilla Wigdor, 1918 has been recorded in 13 families, 30 genera, and 53 species of freshwater fishes across Canada and the United States (Hoffman, 1999). Identification of Rhabdochona species is difficult as many of them have been inadequately or erroneously described, and as pointed out by Sanchez-Alvarez et al. (1998), a detailed taxonomic revision of all putative species in this group warrants initiation. MATERIALS AND METHODS A single adult female blue sucker (557 mm standard length) was collected incidentally by electrofishing on 24 October 1996 from the Mississippi River just below the mouth of the Kaskaskia River, Randolph County, Illinois and was transported alive to the laboratory. -
PALEONTOLOGICAL TECHNICAL REPORT: 6Th AVENUE and WADSWORTH BOULEVARD INTERCHANGE PHASE II ENVIRONMENTAL ASSESSMENT, CITY of LAKEWOOD, JEFFERSON COUNTY, COLORADO
PALEONTOLOGICAL TECHNICAL REPORT: 6th AVENUE AND WADSWORTH BOULEVARD INTERCHANGE PHASE II ENVIRONMENTAL ASSESSMENT, CITY OF LAKEWOOD, JEFFERSON COUNTY, COLORADO Prepared for: TEC Inc. 1746 Cole Boulevard, Suite 265 Golden, CO 80401 Prepared by: Paul C. Murphey, Ph.D. and David Daitch M.S. Rocky Mountain Paleontology 4614 Lonespur Court Oceanside, CA 92056 303-514-1095; 760-758-4019 www.rockymountainpaleontology.com Prepared under State of Colorado Paleontological Permit 2007-33 January, 2007 TABLE OF CONTENTS 1.0 SUMMARY............................................................................................................................. 3 2.0 INTRODUCTION ................................................................................................................... 4 2.1 DEFINITION AND SIGNIFICANCE OF PALEONTOLOGICAL RESOURCES........... 4 3.0 METHODS .............................................................................................................................. 6 4.0. LAWS, ORDINANCES, REGULATIONS AND STANDARDS......................................... 7 4.1. Federal................................................................................................................................. 7 4.2. State..................................................................................................................................... 8 4.3. County................................................................................................................................. 8 4.4. City..................................................................................................................................... -
The Origins of Chordate Larvae Donald I Williamson* Marine Biology, University of Liverpool, Liverpool L69 7ZB, United Kingdom
lopmen ve ta e l B Williamson, Cell Dev Biol 2012, 1:1 D io & l l o l g DOI: 10.4172/2168-9296.1000101 e y C Cell & Developmental Biology ISSN: 2168-9296 Research Article Open Access The Origins of Chordate Larvae Donald I Williamson* Marine Biology, University of Liverpool, Liverpool L69 7ZB, United Kingdom Abstract The larval transfer hypothesis states that larvae originated as adults in other taxa and their genomes were transferred by hybridization. It contests the view that larvae and corresponding adults evolved from common ancestors. The present paper reviews the life histories of chordates, and it interprets them in terms of the larval transfer hypothesis. It is the first paper to apply the hypothesis to craniates. I claim that the larvae of tunicates were acquired from adult larvaceans, the larvae of lampreys from adult cephalochordates, the larvae of lungfishes from adult craniate tadpoles, and the larvae of ray-finned fishes from other ray-finned fishes in different families. The occurrence of larvae in some fishes and their absence in others is correlated with reproductive behavior. Adult amphibians evolved from adult fishes, but larval amphibians did not evolve from either adult or larval fishes. I submit that [1] early amphibians had no larvae and that several families of urodeles and one subfamily of anurans have retained direct development, [2] the tadpole larvae of anurans and urodeles were acquired separately from different Mesozoic adult tadpoles, and [3] the post-tadpole larvae of salamanders were acquired from adults of other urodeles. Reptiles, birds and mammals probably evolved from amphibians that never acquired larvae. -
Digenean Metacercaria (Trematoda, Digenea, Lepocreadiidae) Parasitizing “Coelenterates” (Cnidaria, Scyphozoa and Ctenophora) from Southeastern Brazil
BRAZILIAN JOURNAL OF OCEANOGRAPHY, 53(1/2):39-45, 2005 DIGENEAN METACERCARIA (TREMATODA, DIGENEA, LEPOCREADIIDAE) PARASITIZING “COELENTERATES” (CNIDARIA, SCYPHOZOA AND CTENOPHORA) FROM SOUTHEASTERN BRAZIL André Carrara Morandini1; Sergio Roberto Martorelli2; Antonio Carlos Marques1 & Fábio Lang da Silveira1 1Instituto de Biociências da Universidade de São Paulo Departamento de Zoologia (Caixa Postal 11461, 05422-970, São Paulo, SP, Brazil) 2Centro de Estudios Parasitologicos y Vectores (CEPAVE) (2 Nro. 584 (1900) La Plata, Argentina) e-mails: [email protected], [email protected], [email protected], [email protected] A B S T R A C T Metacercaria specimens of the genus Opechona (Trematoda: Digenea: Lepocreadiidae) are described parasitizing “coelenterates” (scyphomedusae and ctenophores) from Southeastern Brazil (São Paulo state). The worms are compared to other Opechona species occurring on the Brazilian coast, but no association has been made because only adult forms of these species have been described. Suppositions as to the possible transference of the parasites are made. R E S U M O Exemplares de metacercárias do gênero Opechona (Trematoda: Digenea: Lepocreadiidae) são descritos parasitando “celenterados” (cifomedusas e ctenóforos) no sudeste do Brasil (estado de São Paulo). Os vermes foram comparados a outras espécies de Opechona ocorrentes no litoral brasileiro, porém nenhuma associação foi realizada devido às demais espécies terem sido descritas a partir de exemplares adultos. São apresentadas suposições sobre as possíveis formas -
Phylum Arthropod Silvia Rondon, and Mary Corp, OSU Extension Entomologist and Agronomist, Respectively Hermiston Research and Extension Center, Hermiston, Oregon
Phylum Arthropod Silvia Rondon, and Mary Corp, OSU Extension Entomologist and Agronomist, respectively Hermiston Research and Extension Center, Hermiston, Oregon Member of the Phyllum Arthropoda can be found in the seas, in fresh water, on land, or even flying freely; a group with amazing differences of structure, and so abundant that all the other animals taken together are less than 1/6 as many as the arthropods. Well-known members of this group are the Kingdom lobsters, crayfish and crabs; scorpions, spiders, mites, ticks, Phylum Phylum Phylum Class the centipedes and millipedes; and last, but not least, the Order most abundant of all, the insects. Family Genus The Phylum Arthropods consist of the following Species classes: arachnids, chilopods, diplopods, crustaceans and hexapods (insects). All arthropods possess: • Exoskeleton. A hard protective covering around the outside of the body (divided by sutures into plates called sclerites). An insect's exoskeleton (integument) serves as a protective covering over the body, but also as a surface for muscle attachment, a water-tight barrier against desiccation, and a sensory interface with the environment. It is a multi-layered structure with four functional regions: epicuticle (top layer), procuticle, epidermis, and basement membrane. • Segmented body • Jointed limbs and jointed mouthparts that allow extensive specialization • Bilateral symmetry, whereby a central line can divide the body Insect molting or removing its into two identical halves, left and right exoesqueleton • Ventral nerve -
Respiratory Disorders of Fish
This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues. Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. In most cases authors are permitted to post their version of the article (e.g. in Word or Tex form) to their personal website or institutional repository. Authors requiring further information regarding Elsevier’s archiving and manuscript policies are encouraged to visit: http://www.elsevier.com/copyright Author's personal copy Disorders of the Respiratory System in Pet and Ornamental Fish a, b Helen E. Roberts, DVM *, Stephen A. Smith, DVM, PhD KEYWORDS Pet fish Ornamental fish Branchitis Gill Wet mount cytology Hypoxia Respiratory disorders Pathology Living in an aquatic environment where oxygen is in less supply and harder to extract than in a terrestrial one, fish have developed a respiratory system that is much more efficient than terrestrial vertebrates. The gills of fish are a unique organ system and serve several functions including respiration, osmoregulation, excretion of nitroge- nous wastes, and acid-base regulation.1 The gills are the primary site of oxygen exchange in fish and are in intimate contact with the aquatic environment. In most cases, the separation between the water and the tissues of the fish is only a few cell layers thick. Gills are a common target for assault by infectious and noninfectious disease processes.2 Nonlethal diagnostic biopsy of the gills can identify pathologic changes, provide samples for bacterial culture/identification/sensitivity testing, aid in fungal element identification, provide samples for viral testing, and provide parasitic organisms for identification.3–6 This diagnostic test is so important that it should be included as part of every diagnostic workup performed on a fish. -
Book Review: Fishing Into Our Past
Evolutionary Psychology www.epjournal.net – 2008. 6(2): 365-368 ¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯ Book Review Fishing into our Past A review of Neil Shubin, Your Inner Fish: A Journey into the 3.5 Billion-Year History of the Human Body. Allen Lane: London, 2008, 229pp, UK£20, ISBN13: 9780713999358 (Hardcover) Robert King, Department of Psychology, Birkbeck College, University of London, UK. Email: [email protected] I am sure that many of us vividly remember the first time we started to get evolutionary psychology. For me it was like coming out of the optician’s with new glasses and realizing that I had been making do with a terribly short-sighted blur for ages. There is a sort of vertigo attendant on appreciating that the self is not just a few decades old or, as the cultural determinists claimed, centuries old. The realization that our selves could be understood only on the scale of millions of years creates dizziness. It is like that first time lying on one’s back staring into the time machine that is the star-filled night sky and it’s hitting you that many of those stars are now long dead. Those in Evolutionary Psychology (EP) are used to the concept of Deep Time. Some new term needs to be invented for what is stressed in Neil Shubin’s Your Inner Fish. Bottomless Time? Unfathomable Time? Shubin invites us to pan back our usual EP scale by three orders of magnitude from the savannah ape and consider ourselves from the perspective of 3.5 billion years. Of course, in doing this, Shubin is taking us back well beyond the “inner fish” of the title, but it is fish that made Shubin famous.