DOCSLIB.ORG

Hickman, Roberts, Larson

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Hickman, Roberts, Larson hic09617_ch16.qxd 5/30/00 12:43 PM Page 325 CHAPTER 16 Molluscs Phylum Mollusca Fluted giant clam, Tridacna squamosa. A Significant Space space within the mesoderm, the coelom. This meant that the Long ago in the Precambrian era, the most complex animals space was lined with mesoderm and the organs were sus- populating the seas were acoelomate. They must have been pended by mesodermal membranes, the mesenteries. Not inefficient burrowers, and they were unable to exploit the only could the coelom serve as an efficient hydrostatic rich subsurface ooze. Any that developed fluid-filled spaces skeleton, with circular and longitudinal body-wall muscles within the body would have had a substantial selective acting as antagonists, but a more stable arrangement of advantage because these spaces could serve as a hydro- organs with less crowding resulted. Mesenteries provided an static skeleton and improve burrowing efficiency. ideal location for networks of blood vessels, and the ali- The simplest, and probably the first, mode of achieving mentary canal could become more muscular, more highly a fluid-filled space within the body was retention of the specialized, and more diversified without interfering with embryonic blastocoel, as in pseudocoelomates. This was not other organs. the best evolutionary solution because, for example, the Development of a coelom was a major step in the evo- organs lay loose in the body cavity. lution of larger and more complex forms. All the major Some descendants of Precambrian acoelomate organ- groups in chapters to follow are coelomates. I isms evolved a more elegant arrangement: a fluid-filled 325 hic09617_ch16.qxd 5/30/00 12:45 PM Page 326 326 PART 3 The Diversity of Animal Life Position in Animal common ancestor with annelids 3. The efficiency of the respiratory Kingdom before the advent of metamerism. and circulatory systems in the 5. All organ systems are present and cephalopods has made greater body 1. Molluscs are one of the major groups well developed. size possible. Invertebrates reach their of true coelomate animals. largest size in some cephalopods. 2. They belong to the protostome Biological Contributions 4. They have a fleshy mantle that in branch, or schizocoelous coelomates, most cases secretes a shell and is and have spiral cleavage and 1. In molluscs gaseous exchange occurs variously modified for a number of determinate (mosaic) development. not only through the body surface as functions. 3. Many molluscs have a trochophore in phyla discussed previously, but 5. Features unique to the phylum are the larva similar to trochophore larvae of also in specialized respiratory radula and the muscular foot. marine annelids and other marine organs in the form of gills or lungs. 6. The highly developed direct eye of protostomes. Developmental evidence 2. Most classes have an open cephalopods is similar to the indirect thus indicates that molluscs and circulatory system with pumping eye of vertebrates but arises as a skin annelids share a common ancestor. heart, vessels, and blood sinuses. In derivative in contrast to the brain eye 4. Because molluscs are not metameric, most cephalopods the circulatory of vertebrates. they must have diverged from their system is closed. The Molluscs ,Mollusca (mol-lus؅ka) (L. molluscus soft) is one of the largest animal phyla after Arthropoda. There are nearly 50,000 living species and some 35,000 fossil species. The name Mollusca indicates one of their distinctive char- acteristics, a soft body. This very diverse group (Figure 16-1) includes chitons, tooth shells, snails, slugs, A D nudibranchs, sea butterflies, clams, mussels, oysters, squids, octopuses, and nautiluses. The group ranges from fairly simple organisms to some of the most complex of invertebrates, and in size from almost microscopic to the giant squid Architeuthis. These huge molluscs may grow to 18 m long, including their tentacles. They may weigh 450 kg (1,000 pounds). The shells of some giant clams, Tridacna gigas, which inhabit Indo-Pacific coral B E reefs, reach 1.5 m in length and weigh more than 225 kg. These are extremes, Figure 16-1 however, for probably 80% of all mol- Molluscs: a diversity of life forms. The basic luscs are less than 5 cm in maximum body plan of this ancient group has become shell size. The phylum includes some variously adapted for different habitats. A, A of the most sluggish and some of the chiton (Tonicella lineata), Class Polyplacophora. B, A marine snail (Calliostoma annulata), Class swiftest and most active invertebrates. Gastropoda. C, A nudibranch (Chromodoris sp.) It includes herbivorous grazers, preda- Class Gastropoda. D, Pacific giant clam ceous carnivores, filter feeders, detritus (Panope abrupta), with siphons to the left, Class feeders, and parasites. Bivalvia. E, An octopus (Octopus briareus), Molluscs are found in a great range Class Cephalopoda, forages at night on a Caribbean coral reef. of habitats, from the tropics to polar C hic09617_ch16.qxd 5/30/00 12:45 PM Page 327 CHAPTER 16 Molluscs 327 seas, at altitudes exceeding 7000 m, in ponds, lakes, and streams, on mud Characteristics of Phylum (usually three chambered), blood flats, in pounding surf, and in open Mollusca vessels, and sinuses; respiratory pig- ocean from the surface to abyssal ments in blood 1. Body bilaterally symmetrical (bilater- depths. Most of them live in the sea, 8. Gaseous exchange by gills, lungs, al asymmetry in some); unsegment- and they represent a variety of life- mantle, or body surface ed; often with definite head styles, including bottom feeders, bur- 9. One or two kidneys (metaneph- 2. Ventral body wall specialized as a rowers, borers, and pelagic forms. ridia) opening into the pericardial muscular foot, variously modified cavity and usually emptying into the According to fossil evidence, mol- but used chiefly for locomotion luscs originated in the sea, and most of mantle cavity 3. Dorsal body wall forms pair of folds 10. Nervous system of paired cerebral, them have remained there. Much of called the mantle, which encloses their evolution occurred along the pleural, pedal, and visceral ganglia, the mantle cavity, is modified into with nerve cords and subepidermal shores, where food was abundant and gills or lungs, and secretes the plexus; ganglia centralized in nerve habitats were varied. Only bivalves shell (shell absent in some) ring in gastropods and cephalopods and gastropods moved into brackish 4. Surface epithelium usually ciliated 11. Sensory organs of touch, smell, taste, and freshwater habitats. As filter feed- and bearing mucous glands and sen- equilibrium, and vision (in some); ers, bivalves were unable to leave sory nerve endings eyes highly developed in aquatic surroundings. Only snails (gas- 5. Coelom limited mainly to area cephalopods tropods) actually invaded the land. around heart, and perhaps lumen of 12. Internal and external ciliary tracts Terrestrial snails are limited in their gonads and part of kidneys often of great functional importance range by their need for humidity, shel- 6. Complex digestive system; rasping 13. Both monoecious and dioecious ter, and presence of calcium in the soil. organ (radula) usually present; anus forms; spiral cleaveage; larva primi- Many kinds of molluscs are used usually emptying into mantle cavity tively a trochophore, many with a as food. Pearl buttons are obtained 7. Open circulatory system (mostly veliger larva, some with direct from shells of bivalves. The Mississippi closed in cephalopods) of heart development and Missouri river basins have fur- nished material for most of this indus- try in the United States; however, supplies are becoming so depleted that attempts are being made to propagate bers of class Polyplacophora (chitons) Form and Function bivalves artificially. Pearls, both natural are common to abundant marine ani- and cultured, are produced in the mals, especially in the intertidal zone. The enormous variety, great beauty, shells of clams and oysters, most of Bivalves (class Bivalvia) have evolved and easy availability of shells of mol- them in a marine oyster, Meleagrina, many species, both marine and fresh- luscs have made shell collecting a pop- found around eastern Asia. water. Largest and most intelligent of ular pastime. However, many amateur Some molluscs are destructive. Bur- all invertebrates are in the class shell collectors, even though able to rowing shipworms, which are bivalves Cephalopoda (squids, octopuses, and name hundreds of the shells that grace of several species (see Figure 16-27), others). Most abundant and wide- our beaches, know very little about the do great damage to wooden ships and spread of molluscs, however, are snails living animals that created those shells wharves. To prevent the ravages of and their relatives (class Gastropoda). and once lived in them. Reduced to its shipworms, wharves must be either Although enormously diverse, mol- simplest dimensions, the mollusc body creosoted or built of concrete (unfortu- luscs have in common a basic body plan may be said to consist of a head- nately, some ignore the creosote, and plan, which is described later in the foot portion and a visceral mass por- some bivalves bore into concrete). chapter. It seems peculiar, though, that tion (Figure 16-2). The head-foot is the Snails and slugs frequently damage molluscs have failed to exploit the more active area, containing the feed- garden and other vegetation. In addi- coelom. The coelom in molluscs is lim- ing, cephalic sensory, and locomotor tion, snails often serve as intermediate ited to a space around the heart, and organs. It depends primarily on mus- hosts for serious parasites. The boring perhaps around the gonads and part of cular action for its function. The vis- snail Urosalpinx rivals sea stars in the kidneys. Although it develops ceral mass is the portion containing destroying oysters. embryonically in a manner similar to digestive, circulatory, respiratory, and In this chapter we explore the the coelom of annelids, the functional reproductive organs, and it depends various major groups of molluscs, consequences of the space are quite primarily on ciliary tracts for its func- including those that apparently met different.
Load more

Recommended publications
  • Educators' Resource Guide
    EDUCATORS' RESOURCE GUIDE Produced and published by 3D Entertainment Distribution Written by Dr. Elisabeth Mantello In collaboration with Jean-Michel Cousteau’s Ocean Futures Society TABLE OF CONTENTS TO EDUCATORS .................................................................................................p 3 III. PART 3. ACTIVITIES FOR STUDENTS INTRODUCTION .................................................................................................p 4 ACTIVITY 1. DO YOU Know ME? ................................................................. p 20 PLANKton, SOURCE OF LIFE .....................................................................p 4 ACTIVITY 2. discoVER THE ANIMALS OF "SECRET OCEAN" ......... p 21-24 ACTIVITY 3. A. SECRET OCEAN word FIND ......................................... p 25 PART 1. SCENES FROM "SECRET OCEAN" ACTIVITY 3. B. ADD color to THE octoPUS! .................................... p 25 1. CHristmas TREE WORMS .........................................................................p 5 ACTIVITY 4. A. WHERE IS MY MOUTH? ..................................................... p 26 2. GIANT BasKET Star ..................................................................................p 6 ACTIVITY 4. B. WHat DO I USE to eat? .................................................. p 26 3. SEA ANEMONE AND Clown FISH ......................................................p 6 ACTIVITY 5. A. WHO eats WHat? .............................................................. p 27 4. GIANT CLAM AND ZOOXANTHELLAE ................................................p
    [Show full text]
  • Long-Duration Anesthetization of Squid (Doryteuthis Pealeii) T
    Marine and Freshwater Behaviour and Physiology Vol. 43, No. 4, July 2010, 297–303 Long-duration anesthetization of squid (Doryteuthis pealeii) T. Aran Mooneya,b*, Wu-Jung Leeb and Roger T. Hanlona aMarine Resources Center, Marine Biological Laboratory, Woods Hole, MA 02543, USA; bWoods Hole Oceanographic Institution, Woods Hole, MA 02543, USA (Received 4 May 2010; final version received 15 June 2010) Cephalopods, and particularly squid, play a central role in marine ecosystems and are a prime model animal in neuroscience. Yet, the capability to investigate these animals in vivo has been hampered by the inability to sedate them beyond several minutes. Here, we describe methods to anesthetize Doryteuthis pealeii, the longfin squid, noninvasively for up to 5 h using a 0.15 mol magnesium chloride (MgCl2) seawater solution. Sedation was mild, rapid (54 min), and the duration could be easily controlled by repeating anesthetic inductions. The sedation had no apparent effect on physiological evoked potentials recorded from nerve bundles within the statocyst system, suggesting the suitability of this solution as a sedating agent. This simple, long-duration anesthetic technique opens the possibility for longer in vivo investigations on this and related cephalopods, thus expanding potential neuroethological and ecophysiology research for a key marine invertebrate group. Keywords: anesthesia; sedation; squid; Loligo; neurophysiology; giant axon Introduction Although cephalopods are key oceanic organisms used extensively as experimental animals in a variety of research fields (Gilbert et al. 1990), there is a relative paucity of information on maintaining them under anesthesia for prolonged durations. Lack of established protocols for sedation beyond several minutes constrains Downloaded By: [Hanlon, Roger T.] At: 12:46 19 August 2010 experimental conditions for many neurobiological and physiological preparations.
    [Show full text]
  • Shell Morphology, Radula and Genital Structures of New Invasive Giant African Land
    bioRxiv preprint doi: https://doi.org/10.1101/2019.12.16.877977; this version posted December 16, 2019. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY 4.0 International license. 1 Shell Morphology, Radula and Genital Structures of New Invasive Giant African Land 2 Snail Species, Achatina fulica Bowdich, 1822,Achatina albopicta E.A. Smith (1878) and 3 Achatina reticulata Pfeiffer 1845 (Gastropoda:Achatinidae) in Southwest Nigeria 4 5 6 7 8 9 Alexander B. Odaibo1 and Suraj O. Olayinka2 10 11 1,2Department of Zoology, University of Ibadan, Ibadan, Nigeria 12 13 Corresponding author: Alexander B. Odaibo 14 E.mail :[email protected] (AB) 15 16 17 18 1 bioRxiv preprint doi: https://doi.org/10.1101/2019.12.16.877977; this version posted December 16, 2019. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY 4.0 International license. 19 Abstract 20 The aim of this study was to determine the differences in the shell, radula and genital 21 structures of 3 new invasive species, Achatina fulica Bowdich, 1822,Achatina albopicta E.A. 22 Smith (1878) and Achatina reticulata Pfeiffer, 1845 collected from southwestern Nigeria and to 23 determine features that would be of importance in the identification of these invasive species in 24 Nigeria.
    [Show full text]
  • Microchemistry of Juvenile Mercenaria Mercenaria Shell: Implications for Modeling Larval Dispersal
    Vol. 465: 155–168, 2012 MARINE ECOLOGY PROGRESS SERIES Published September 28 doi: 10.3354/meps09895 Mar Ecol Prog Ser Microchemistry of juvenile Mercenaria mercenaria shell: implications for modeling larval dispersal A. M. Cathey1,*, N. R. Miller2, D. G. Kimmel3 1Department of Biology, East Carolina University, Greenville, North Carolina 27858, USA 2Department of Geological Sciences, The University of Texas at Austin, Austin, Texas 78712, USA 3Department of Biology, Institute for Coastal Science and Policy, East Carolina University, Greenville, North Carolina 27858, USA ABSTRACT: The elemental signature of trace and minor elements within biominerals has been used to investigate the larval dispersal of bivalves. We investigated the potential of this technique by examining elemental signals in juvenile shells of the hard clam Mercenaria mercenaria within an estuarine−lagoonal system near Cape Lookout, North Carolina, USA. We assessed the spatial distinction (~12 to 40 km) and temporal stability (fall versus spring) of elemental concentrations using inductively coupled plasma mass spectrometry (ICP-MS). Twelve minor and trace elements were present at detectable levels in all shell samples: calcium (Ca), manganese (Mn), aluminum (Al), titanium (Ti), cobalt (Co), copper (Cu), barium (Ba), magnesium (Mg), zinc (Zn), lead (Pb), nickel (Ni), and strontium (Sr). Discriminant function analyses (DFA) using metal to Ca ratios as independent variables correctly assigned hard clams to their site of collection with 100% success from both fall and spring sampling events. Mn:Ca ratio proved to be the most effective discrimi- nator explaining 91.2 and 71.9% of our among-group variance, respectively. Elemental concentra- tions within juvenile shell differed temporally.
    [Show full text]
  • CHAPTER 10 MOLLUSCS 10.1 a Significant Space A
    PART file:///C:/DOCUME~1/ROBERT~1/Desktop/Z1010F~1/FINALS~1.HTM CHAPTER 10 MOLLUSCS 10.1 A Significant Space A. Evolved a fluid-filled space within the mesoderm, the coelom B. Efficient hydrostatic skeleton; room for networks of blood vessels, the alimentary canal, and associated organs. 10.2 Characteristics A. Phylum Mollusca 1. Contains nearly 75,000 living species and 35,000 fossil species. 2. They have a soft body. 3. They include chitons, tooth shells, snails, slugs, nudibranchs, sea butterflies, clams, mussels, oysters, squids, octopuses and nautiluses (Figure 10.1A-E). 4. Some may weigh 450 kg and some grow to 18 m long, but 80% are under 5 centimeters in size. 5. Shell collecting is a popular pastime. 6. Classes: Gastropoda (snails…), Bivalvia (clams, oysters…), Polyplacophora (chitons), Cephalopoda (squids, nautiluses, octopuses), Monoplacophora, Scaphopoda, Caudofoveata, and Solenogastres. B. Ecological Relationships 1. Molluscs are found from the tropics to the polar seas. 2. Most live in the sea as bottom feeders, burrowers, borers, grazers, carnivores, predators and filter feeders. 1. Fossil evidence indicates molluscs evolved in the sea; most have remained marine. 2. Some bivalves and gastropods moved to brackish and fresh water. 3. Only snails (gastropods) have successfully invaded the land; they are limited to moist, sheltered habitats with calcium in the soil. C. Economic Importance 1. Culturing of pearls and pearl buttons is an important industry. 2. Burrowing shipworms destroy wooden ships and wharves. 3. Snails and slugs are garden pests; some snails are intermediate hosts for parasites. D. Position in Animal Kingdom (see Inset, page 172) E.
    [Show full text]
  • Octopus Consciousness: the Role of Perceptual Richness
    Review Octopus Consciousness: The Role of Perceptual Richness Jennifer Mather Department of Psychology, University of Lethbridge, Lethbridge, AB T1K 3M4, Canada; [email protected] Abstract: It is always difficult to even advance possible dimensions of consciousness, but Birch et al., 2020 have suggested four possible dimensions and this review discusses the first, perceptual richness, with relation to octopuses. They advance acuity, bandwidth, and categorization power as possible components. It is first necessary to realize that sensory richness does not automatically lead to perceptual richness and this capacity may not be accessed by consciousness. Octopuses do not discriminate light wavelength frequency (color) but rather its plane of polarization, a dimension that we do not understand. Their eyes are laterally placed on the head, leading to monocular vision and head movements that give a sequential rather than simultaneous view of items, possibly consciously planned. Details of control of the rich sensorimotor system of the arms, with 3/5 of the neurons of the nervous system, may normally not be accessed to the brain and thus to consciousness. The chromatophore-based skin appearance system is likely open loop, and not available to the octopus’ vision. Conversely, in a laboratory situation that is not ecologically valid for the octopus, learning about shapes and extents of visual figures was extensive and flexible, likely consciously planned. Similarly, octopuses’ local place in and navigation around space can be guided by light polarization plane and visual landmark location and is learned and monitored. The complex array of chemical cues delivered by water and on surfaces does not fit neatly into the components above and has barely been tested but might easily be described as perceptually rich.
    [Show full text]
  • Comparative Neuroanatomy of Mollusks and Nemerteans in the Context of Deep Metazoan Phylogeny
    Comparative Neuroanatomy of Mollusks and Nemerteans in the Context of Deep Metazoan Phylogeny Von der Fakultät für Mathematik, Informatik und Naturwissenschaften der RWTH Aachen University zur Erlangung des akademischen Grades einer Doktorin der Naturwissenschaften genehmigte Dissertation vorgelegt von Diplom-Biologin Simone Faller aus Frankfurt am Main Berichter: Privatdozent Dr. Rudolf Loesel Universitätsprofessor Dr. Peter Bräunig Tag der mündlichen Prüfung: 09. März 2012 Diese Dissertation ist auf den Internetseiten der Hochschulbibliothek online verfügbar. Contents 1 General Introduction 1 Deep Metazoan Phylogeny 1 Neurophylogeny 2 Mollusca 5 Nemertea 6 Aim of the thesis 7 2 Neuroanatomy of Minor Mollusca 9 Introduction 9 Material and Methods 10 Results 12 Caudofoveata 12 Scutopus ventrolineatus 12 Falcidens crossotus 16 Solenogastres 16 Dorymenia sarsii 16 Polyplacophora 20 Lepidochitona cinerea 20 Acanthochitona crinita 20 Scaphopoda 22 Antalis entalis 22 Entalina quinquangularis 24 Discussion 25 Structure of the brain and nerve cords 25 Caudofoveata 25 Solenogastres 26 Polyplacophora 27 Scaphopoda 27 i CONTENTS Evolutionary considerations 28 Relationship among non-conchiferan molluscan taxa 28 Position of the Scaphopoda within Conchifera 29 Position of Mollusca within Protostomia 30 3 Neuroanatomy of Nemertea 33 Introduction 33 Material and Methods 34 Results 35 Brain 35 Cerebral organ 38 Nerve cords and peripheral nervous system 38 Discussion 38 Peripheral nervous system 40 Central nervous system 40 In search for the urbilaterian brain 42 4 General Discussion 45 Evolution of higher brain centers 46 Neuroanatomical glossary and data matrix – Essential steps toward a cladistic analysis of neuroanatomical data 49 5 Summary 53 6 Zusammenfassung 57 7 References 61 Danksagung 75 Lebenslauf 79 ii iii 1 General Introduction Deep Metazoan Phylogeny The concept of phylogeny follows directly from the theory of evolution as published by Charles Darwin in The origin of species (1859).
    [Show full text]
  • Defining Phyla: Evolutionary Pathways to Metazoan Body Plans
    EVOLUTION & DEVELOPMENT 3:6, 432-442 (2001) Defining phyla: evolutionary pathways to metazoan body plans Allen G. Collins^ and James W. Valentine* Museum of Paleontology and Department of Integrative Biology, University of California, Berkeley, CA 94720, USA 'Author for correspondence (email: [email protected]) 'Present address: Section of Ecology, Befiavior, and Evolution, Division of Biology, University of California, San Diego, La Jolla, CA 92093-0116, USA SUMMARY Phyla are defined by two sets of criteria, one pothesis of Nielsen; the clonal hypothesis of Dewel; the set- morphological and the other historical. Molecular evidence aside cell hypothesis of Davidson et al.; and a benthic hy- permits the grouping of animals into clades and suggests that pothesis suggested by the fossil record. It is concluded that a some groups widely recognized as phyla are paraphyletic, benthic radiation of animals could have supplied the ances- while some may be polyphyletic; the phyletic status of crown tral lineages of all but a few phyla, is consistent with molecu- phyla is tabulated. Four recent evolutionary scenarios for the lar evidence, accords well with fossil evidence, and accounts origins of metazoan phyla and of supraphyletic clades are as- for some of the difficulties in phylogenetic analyses of phyla sessed in the light of a molecular phylogeny: the trochaea hy- based on morphological criteria. INTRODUCTION Molecules have provided an important operational ad- vance to addressing questions about the origins of animal Concepts of animal phyla have changed importantly from phyla. Molecular developmental and comparative genomic their origins in the six Linnaean classis and four Cuvieran evidence offer insights into the genetic bases of body plan embranchements.
    [Show full text]
  • Age, Growth, Size at Sexual Maturity and Reproductive Biology of Channeled Whelk, Busycotypus Canaliculatus, in the U.S
    Age, Growth, Size at Sexual Maturity and Reproductive Biology of Channeled Whelk, Busycotypus canaliculatus, in the U.S. Mid-Atlantic October 2015 Robert A. Fisher Virginia Institute of Marine Science Virginia Sea Grant-Affiliated Extension (In cooperation with Bernie’s Conchs) Robert A. Fisher Marine Advisory Services Virginia Institute of Marine Science P.O. Box 1346 Gloucester Point, VA 23062 804/684-7168 [email protected] www.vims.edu/adv VIMS Marine Resource Report No. 2015-15 VSG-15-09 Additional copies of this publication are available from: Virginia Sea Grant Communications Virginia Institute of Marine Science P.O. Box 1346 Gloucester Point, VA 23062 804/684-7167 [email protected] Cover Photo: Robert Fisher, VIMS MAS This work is affiliated with the Virginia Sea Grant Program, by NOAA Office of Sea Grant, U.S. Depart- ment of Commerce, under Grant No. NA10OAR4170085. The views expressed herein do not necessar- ily reflect the views of any of those organizations. Age, Growth, Size at Sexual Maturity and Reproductive Biology of Channeled Whelk, Busycotypus canaliculatus, in the U.S. Mid-Atlantic Final Report for the Virginia Fishery Resource Grant Program Project 2009-12 Abstract The channeled whelk, Busycotypus canaliculatus, was habitats, though mixing is observed inshore along shallow sampled from three in-shore commercially harvested waters of continental shelf. Channeled whelks are the resource areas in the US Mid-Atlantic: off Ocean City, focus of commercial fisheries throughout their range (Davis Maryland (OC); Eastern Shore of Virginia (ES); and and Sisson 1988, DiCosimo 1988, Bruce 2006, Fisher and Virginia Beach, Virginia (VB).
    [Show full text]
  • OREGON ESTUARINE INVERTEBRATES an Illustrated Guide to the Common and Important Invertebrate Animals
    OREGON ESTUARINE INVERTEBRATES An Illustrated Guide to the Common and Important Invertebrate Animals By Paul Rudy, Jr. Lynn Hay Rudy Oregon Institute of Marine Biology University of Oregon Charleston, Oregon 97420 Contract No. 79-111 Project Officer Jay F. Watson U.S. Fish and Wildlife Service 500 N.E. Multnomah Street Portland, Oregon 97232 Performed for National Coastal Ecosystems Team Office of Biological Services Fish and Wildlife Service U.S. Department of Interior Washington, D.C. 20240 Table of Contents Introduction CNIDARIA Hydrozoa Aequorea aequorea ................................................................ 6 Obelia longissima .................................................................. 8 Polyorchis penicillatus 10 Tubularia crocea ................................................................. 12 Anthozoa Anthopleura artemisia ................................. 14 Anthopleura elegantissima .................................................. 16 Haliplanella luciae .................................................................. 18 Nematostella vectensis ......................................................... 20 Metridium senile .................................................................... 22 NEMERTEA Amphiporus imparispinosus ................................................ 24 Carinoma mutabilis ................................................................ 26 Cerebratulus californiensis .................................................. 28 Lineus ruber .........................................................................
    [Show full text]
  • Mollusca, Archaeogastropoda) from the Northeastern Pacific
    Zoologica Scripta, Vol. 25, No. 1, pp. 35-49, 1996 Pergamon Elsevier Science Ltd © 1996 The Norwegian Academy of Science and Letters Printed in Great Britain. All rights reserved 0300-3256(95)00015-1 0300-3256/96 $ 15.00 + 0.00 Anatomy and systematics of bathyphytophilid limpets (Mollusca, Archaeogastropoda) from the northeastern Pacific GERHARD HASZPRUNAR and JAMES H. McLEAN Accepted 28 September 1995 Haszprunar, G. & McLean, J. H. 1995. Anatomy and systematics of bathyphytophilid limpets (Mollusca, Archaeogastropoda) from the northeastern Pacific.—Zool. Scr. 25: 35^9. Bathyphytophilus diegensis sp. n. is described on basis of shell and radula characters. The radula of another species of Bathyphytophilus is illustrated, but the species is not described since the shell is unknown. Both species feed on detached blades of the surfgrass Phyllospadix carried by turbidity currents into continental slope depths in the San Diego Trough. The anatomy of B. diegensis was investigated by means of semithin serial sectioning and graphic reconstruction. The shell is limpet­ like; the protoconch resembles that of pseudococculinids and other lepetelloids. The radula is a distinctive, highly modified rhipidoglossate type with close similarities to the lepetellid radula. The anatomy falls well into the lepetelloid bauplan and is in general similar to that of Pseudococculini- dae and Pyropeltidae. Apomorphic features are the presence of gill-leaflets at both sides of the pallial roof (shared with certain pseudococculinids), the lack of jaws, and in particular many enigmatic pouches (bacterial chambers?) which open into the posterior oesophagus. Autapomor- phic characters of shell, radula and anatomy confirm the placement of Bathyphytophilus (with Aenigmabonus) in a distinct family, Bathyphytophilidae Moskalev, 1978.
    [Show full text]
  • Nervous System in Gastropoda
    Nervous System in Gastropoda The nervous system consists of ganglia, commissures, connectives and the nerves to different organs. (i) Ganglia: A small compact mass of nerve cells and connective tissue is called ganglion. The main ganglia are: (1) One pair of roughly traingular cerebral ganglia situated on the dorsolateral sides of the buccal mass, one on each side of the head. (2) One pair of pleuropedal ganglia placed below the buccal mass on the lateral side. Each pleuropedal ganglionic mass is more or less rectangular in outline and is formed by the fusion of pleural and pedal ganglia. The infraintestinal ganglion is also fused with the right pleuropedal mass. (3) Visceral ganglion is very large and appears to be unpaired. It is a bilobed structure and is formed by the fusion of two separate ganglia. The visceral ganglion is placed posteriorly very close to the heart. (4) A pair of buccal ganglia are situated on the buccal mass on the two sides of the oesophagus. (5) A single supraintestinal ganglion is located near the middle of the left pleurovisceral connectives (Fig. 16.18). ii) Commissures: The nerve connections between two similar ganglia are generally called commissures. The ganglia are placed on the opposite sides of the body. Two cerebral ganglia are connected by a thick nerve cord, called the cerebral commissure. The buccal ganglia are also connected by a delicate buccal commissure. The inner sides of the pleuropedal ganglia are connected by a broad nerve, called the pedal commissure. ( (iii) Connectives: The nerve connections between two dissimilar ganglia are usually called connectives.
    [Show full text]