DOCSLIB.ORG

Phylum Mollusca; Ziser Lecture Notes, 2012.10 1 Animals: Phylum Mollusca; Ziser Lecture Notes, 2012.10 2

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Phylum Mollusca; Ziser Lecture Notes, 2012.10 1 Animals: Phylum Mollusca; Ziser Lecture Notes, 2012.10 2 Eucoelomates most invertebrate coelomates are protostomes animals having a true coelom are referred to as being in deuterostomes, the coelom appears as eucoelomates outpocketings of the archenteron eucoelomate animals have a body cavity that is echinoderms and chordates and a few minor phyla are deuterostomes completely lined with mesoderm the mesoderm can develop into muscle layers & internal skeletal elements ! a large fluid filled coelom surrounded by muscle layers makes a more effective hydrostatic skeleton in many worms ! mesodermal layers lead to development of arteries and veins, ie circulatory systems; better blood supply to all internal organs ! since mesoderm lines the digestive tract, this allows for the development of much more elaborate digestive organs eg. compare the digestive tract of earthworms to Ascaris. ! mesenteries to support internal organs there are 2 main ways that a true coelom can develop in an embryo: in protostomes the coelom appears as a split in the mesoderm layer of the embryo Animals: Phylum Mollusca; Ziser Lecture Notes, 2012.10 1 Animals: Phylum Mollusca; Ziser Lecture Notes, 2012.10 2 Animals – Molluscs the polar seas 110,000 living; 70,000 fossils occur from the bottom of the oceans to 7000 M above sea level second largest phylum of animals in terms of number of known species typical fauna of all parts of the ocean, ponds, lakes, streams and rivers, mudflats, intertidal most versatile body plan of all animals and terrestrial habitats range from fairly simple organisms to some of the bottom feeders, planktonic, burrowers, borers, most complex and specialized of invertebrates pelagic forms includes: snails, limpets, clams, mussels, chitons, one group, cephalopods, are considered the most octopus, squid, oysters, slugs, nautilus, tooth intelligent of all invertebrates shells the phylum originated in the sea and most of them good fossil record; since most secrete a shell remain there all living classes were well established early in the ! only bivalves and snails moved to brackish fossil record and freshwaters but did not become dominant until the ! only snails invaded land brachiopods mostly died out in the Permian Extinction (~250 MY ago) mollusks are closely related to segmented worms microscopic to 20 M (50-60’ = giant squid) and up to 900 kg (1980 lbs; ~ 1 ton) ! same larval form = trochophore eg. Tridacna 1.5 M and 250 kg (500 lbs) Body Plan but most (80%) less than 10 cm (~4”) well developed bilateral symmetry molluscs are mostly aquatic; found from the tropics to most are unsegmented Animals: Phylum Mollusca; Ziser Lecture Notes, 2012.10 3 Animals: Phylum Mollusca; Ziser Lecture Notes, 2012.10 4 but is greatly reduced to a small space around a few primitive forms seem to show some segmentation. the heart most molluscs (except bivalves) have a well developed head it has become part of an open circulatory system bears mouth and various sense organs in some mollusks the mantle hangs down to create in spite of wide diversity of group most share mantle cavity around the internal organs basic features of body plan: houses respiratory organs; gills mantle - secretes shell or becomes outer body covering itself sometimes the mantle itself serves as a shell - (internal or external) radula – specialized feeding organ in mouth respiratory organ foot - usually used for locomotion products from the digestive, excretory & 1. Mantle reproductive systems empty into mantle cavity before release the body wall of mollusks consists of an outer layer of epidermis that extends over most of a continuous current of water is created by the animal as a mantle cilia to bring in food and oxygen and to remove wastes and gametes often contains various sense organs some molluscs are able to retract head or foot into eg. ocelli, sensory papillae mantle cavity for protection glands in epidermis secretes mucous, cement and sometimes a shell 2. Shell mantle is underlain by complex layers of muscle in most molluscs the mantle secretes a shell and connective tissues which serves as a protective exoskeleton the body cavity of molluscs is a true coelom great variation in shell form and structure Animals: Phylum Mollusca; Ziser Lecture Notes, 2012.10 5 Animals: Phylum Mollusca; Ziser Lecture Notes, 2012.10 6 shell made of calcium carbonate in some such as squid and octopus the shell is internal and greatly reduced calcium extracted from water, soil or food the mantle serves as the animals outer shell is composed of 3 layers: covering periostracum = outer 3. Radula especially thick in freshwater molluscs ! protects from acidity common in fw in mouth is tongue-like rasping organ = radula in many marine forms this layer is thin or absent found in all groups except bivalves and aplacophora (solenogastres) prismatic layer = middle hardened file-like, up to 250,000 tiny teeth dense prisms of calcium carbonate crystals in protein matrix the numbers and pattern of teeth are used to identify certain species nacreous layer = inner new rows of teeth are continually added to the gloss film of calcium carbonate sheets back of the radula ad the front teeth are secreted continuously through live worn down thickens the radula is supported by a cartilage-like rod produces irridescent “mother of pearl” (=odontophore) shell appears in embryo used to scrape, pierce, tear or cut food grows throughout life ! often growth lines radula also acts as a conveyor belt to move food usually used for protection toward the digestive tract 4. Foot but some bivalves use shell to rasp into wood or rock all molluscs have a thick muscular foot Animals: Phylum Mollusca; Ziser Lecture Notes, 2012.10 7 Animals: Phylum Mollusca; Ziser Lecture Notes, 2012.10 8 variously modified for locomotion: in mouth is tonguelike rasping organ = radula creeping movements - produced by waves of muscular contractions that move through foot most internal organs, including the digestive system or by creating a slime trail from mucous glands in the are embedded in solid tissue called the visceral foot mass, instead of being free inside a body cavity eg. snails ! gliding movement (coelom) or digging into sediment complete digestive tract divided into discrete, being extended from body into sediment functionally specialized regions: hydraulically by engorging with blood to anchor then draw rest of body into sediment foregut eg. bivalves eg. scaphopoda buccal cavity mouth, radula, salivary glands, esophagus or for attachment: receives and prepares food may secrete mucus to adhere to solid substrate midgut eg. limpets, chitons, land snails stomach and associated digestive glands sorting region, crushing region the foot of many bivalves contain a gland that produces crystalline style in some to grind food byssal threads (sea silk) for attachment some digestion takes place in digestive gland silky filaments of keratin and other proteins hindgut attached to substrate by extremely effective cement intestine usually long and coiled absorption of nutrients in some molluscs a portion of the foot is modified formation of feces (undigested residue) into a long tubular proboscis for feeding Respiration Feeding and Digestion most mollusks have folded, ciliated gills (=ctenidia) detritus feeders, burrowers, borers, grazers, carnivores, filter feeders, etc !thin feathery sheets of tissue covered with cilia Animals: Phylum Mollusca; Ziser Lecture Notes, 2012.10 9 Animals: Phylum Mollusca; Ziser Lecture Notes, 2012.10 10 oxygen carrying cells with pigments to improve also used for feeding in bivalves efficiency of oxygen transport: some mollusks breath through their skin haemocyanin (Cu) - most - blue some with hemoglobin (Fe) - red many terresrial snails lack gills (=pulmonates) some white blood cells !mantle is modified into a saclike “lung” for no clotting agents or thrombocytes breathing air cephalopods have a closed circulatory system Circulation Nervous & Endocrine Systems open circulatory system in most CNS is a ring of ganglia in head area with paired nerves and ganglia extending to other parts of the ! blood not entirely contained within vessels body works good for slow moving animals eg. pedal ganglia ! control foot ! the most active molluscs, the cephalopods, have a closed also well developed endocrine system circulatory system simple heart with a few vessels ! controls egg laying and growth heart with 2 auricles and 1 ventricle cephalopods show some intelligence extending from heart is aorta are active predators reduced coelom becomes a haemocoel surrounding ! can recognize prey with sharp eyes heart ! can learn by watching blood contains several kinds of cells: Excretion Animals: Phylum Mollusca; Ziser Lecture Notes, 2012.10 11 Animals: Phylum Mollusca; Ziser Lecture Notes, 2012.10 12 usually 1 pair of nephridia (=metanephridia) some freshwater bivalves produce a parasitic larva = glochidium often called kidneys (not really true kidneys) it attaches to gills of host fish and (metanephridium consist of a tube that opens into body cavity feeds on blood at one end and drains to the outside) in many species the nephridial tubule also acts as development is direct, ie. no larval stage: gonoduct in cephalopods, many freshwater snails and some bivalves some molluscs have several pairs of nephridia some excretion occurs through body wall and gills Reproduction & Development most molluscs are dioecious; some are monoecious many marine forms produce characteristic larva = trochophore same larval form is found in some flatworms, annelids and a few other minor phyla in some gastropods and bivalves
Load more

Recommended publications
  • The Pax Gene Family: Highlights from Cephalopods Sandra Navet, Auxane Buresi, Sébastien Baratte, Aude Andouche, Laure Bonnaud-Ponticelli, Yann Bassaglia
    The Pax gene family: Highlights from cephalopods Sandra Navet, Auxane Buresi, Sébastien Baratte, Aude Andouche, Laure Bonnaud-Ponticelli, Yann Bassaglia To cite this version: Sandra Navet, Auxane Buresi, Sébastien Baratte, Aude Andouche, Laure Bonnaud-Ponticelli, et al.. The Pax gene family: Highlights from cephalopods. PLoS ONE, Public Library of Science, 2017, 12 (3), pp.e0172719. 10.1371/journal.pone.0172719. hal-01921138 HAL Id: hal-01921138 https://hal.archives-ouvertes.fr/hal-01921138 Submitted on 13 Nov 2018 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Distributed under a Creative Commons Attribution| 4.0 International License RESEARCH ARTICLE The Pax gene family: Highlights from cephalopods Sandra Navet1☯, Auxane Buresi1☯, SeÂbastien Baratte1,2, Aude Andouche1, Laure Bonnaud-Ponticelli1, Yann Bassaglia1,3* 1 UMR BOREA MNHN/CNRS7208/IRD207/UPMC/UCN/UA, MuseÂum National d'Histoire Naturelle, Sorbonne UniversiteÂs, Paris, France, 2 Univ. Paris Sorbonne-ESPE, Sorbonne UniversiteÂs, Paris, France, 3 Univ. Paris Est CreÂteil-Val de Marne, CreÂteil, France ☯ These authors contributed equally to this work. * [email protected] a1111111111 a1111111111 a1111111111 a1111111111 Abstract a1111111111 Pax genes play important roles in Metazoan development. Their evolution has been exten- sively studied but Lophotrochozoa are usually omitted.
    [Show full text]
  • Interpreting Amphioxus, and Thoughts on Ancestral Chordate Mouths and Brains THURSTON LACALLI*
    Int. J. Dev. Biol. 61: 649-654 (2017) doi: 10.1387/ijdb.170105tl www.intjdevbiol.com Interpreting amphioxus, and thoughts on ancestral chordate mouths and brains THURSTON LACALLI* Biology Department, University of Victoria, Victoria, Canada ABSTRACT Amphioxus is increasingly important as a model for ancestral chordates. Nevertheless, it is secondarily modified in various ways, especially in the larva, whose small size has resulted in a rescaling and repositioning of structures. This is especially pronounced in the head region, where the mouth opens asymmetrically on the left side, leading to speculation that the mouth is sec- ondarily derived, e.g. from a gill slit, and is hence not homologous with mouths in other animals. The available evidence does not, in the author’s view, support this interpretation. A second issue is raised concerning the identity and function of the midbrain homolog, whose extent depends on whether greater weight is given to dorsal landmarks in the nerve cord or ventral ones. The presence of two sets of dorsal photoreceptors, the lamellar body and Joseph cells, functionally links the region they occupy to the vertebrate midbrain. The midbrain is currently suggested to be the brain region in which primary consciousness emerged during early vertebrate evolution, so the origin of its constituent cells is of special interest. Possible amphioxus homologs include the anterior-most group of dorsal bipolar cells (ADBs), which are apico-basally inverted (i.e. synapse-bearing neurites arise from the apical cell compartment) in the same fashion as cortical neurons in vertebrates. This may have been a crucial innovation for chordates, responsible for both improved sensory process- ing and, eventually, consciousness.
    [Show full text]
  • Gastropoda: Turbinellidae)
    Ruthenica, 200 I, II (2): 81-136. ©Ruthenica, 2001 A revision of the Recent species of Exilia, formerly Benthovoluta (Gastropoda: Turbinellidae) I 2 3 Yuri I. KANTOR , Philippe BOUCHET , Anton OLEINIK 1 A.N. Severtzov Institute of Problems of Evolution of the Russian Academy of Sciences, Leninski prosp. 33, Moscow 117071, RUSSIA; 2 Museum national d'Histoire naturelle, 55, Rue BufJon, 75005 Paris, FRANCE; 3 Department of Geography & Geology Florida Atlantic University, 777 Glades Rd, Physical Sciences Building, PS 336, Boca Raton FL 33431-0991, USA ABSTRACT. The range of shell characters (overall established among some of these nominal taxa. shape, sculpture, columellar plaits, protoconchs) Schematically, Exilia Conrad, 1860, Palaeorhaphis exhibited by fossil and Recent species placed in Stewart, 1927, and Graphidula Stephenson, 1941 Exilia Conrad, 1860, Mitraefusus Bellardi, 1873, are currently used as valid genera for Late Creta­ Mesorhytis Meek, 1876, Surculina Dall, 1908, Phe­ ceous to Neogene fossils; and Surculina Dall, 1908 nacoptygma Dall, 1918, Palaeorhaphis Stewart, 1927, and Benthovoluta Kuroda et Habe, 1950 are cur­ Zexilia Finlay, 1926, Graphidula Stephenson, 1941, rently used as valid genera for Recent deep-water Benthovoluta Kuroda et Habe, 1950, and Chatha­ species from middle to low latitudes. Each of these midia Dell, 1956 and the anatomy of the Recent nominal taxa has had a complex history of family species precludes separation of more than one genus. allocation, which has not facilitated comparisons Consequently all of these nominal genera are sy­ on a broader scale. Exilia and Benthovoluta are the nonymised with Exilia, with a stratigraphical range genera best known in the fossil and Recent litera­ from Late Cretaceous to Recent.
    [Show full text]
  • Deep-Water Buccinidae (Gastropoda: Neogastropoda) from Sunken Wood, Vents and Seeps: Molecular Phylogeny and Taxonomy Yu.I
    Deep-water Buccinidae (Gastropoda: Neogastropoda) from sunken wood, vents and seeps: molecular phylogeny and taxonomy Yu.I. Kantor, N. Puillandre, K. Fraussen, A.E. Fedosov, P. Bouchet To cite this version: Yu.I. Kantor, N. Puillandre, K. Fraussen, A.E. Fedosov, P. Bouchet. Deep-water Buccinidae (Gas- tropoda: Neogastropoda) from sunken wood, vents and seeps: molecular phylogeny and taxonomy. Journal of the Marine Biological Association of the UK, Cambridge University Press (CUP), 2013, 93 (8), pp.2177-2195. 10.1017/S0025315413000672. hal-02458197 HAL Id: hal-02458197 https://hal.archives-ouvertes.fr/hal-02458197 Submitted on 28 Jan 2020 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Deep-water Buccinidae (Gastropoda: Neogastropoda) from sunken wood, vents and seeps: Molecular phylogeny and taxonomy KANTOR YU.I.1, PUILLANDRE N.2, FRAUSSEN K.3, FEDOSOV A.E.1, BOUCHET P.2 1 A.N. Severtzov Institute of Ecology and Evolution of Russian Academy of Sciences, Leninski Prosp. 33, Moscow 119071, Russia, 2 Muséum National d’Histoire Naturelle, Departement Systematique et Evolution, UMR 7138, 43, Rue Cuvier, 75231 Paris, France, 3 Leuvensestraat 25, B–3200 Aarschot, Belgium ABSTRACT Buccinidae - like other canivorous and predatory molluscs - are generally considered to be occasional visitors or rare colonizers in deep-sea biogenic habitats.
    [Show full text]
  • Zoology Lab Manual
    General Zoology Lab Supplement Stephen W. Ziser Department of Biology Pinnacle Campus To Accompany the Zoology Lab Manual: Smith, D. G. & M. P. Schenk Exploring Zoology: A Laboratory Guide. Morton Publishing Co. for BIOL 1413 General Zoology 2017.5 Biology 1413 Introductory Zoology – Supplement to Lab Manual; Ziser 2015.12 1 General Zoology Laboratory Exercises 1. Orientation, Lab Safety, Animal Collection . 3 2. Lab Skills & Microscopy . 14 3. Animal Cells & Tissues . 15 4. Animal Organs & Organ Systems . 17 5. Animal Reproduction . 25 6. Animal Development . 27 7. Some Animal-Like Protists . 31 8. The Animal Kingdom . 33 9. Phylum Porifera (Sponges) . 47 10. Phyla Cnidaria (Jellyfish & Corals) & Ctenophora . 49 11. Phylum Platyhelminthes (Flatworms) . 52 12. Phylum Nematoda (Roundworms) . 56 13. Phyla Rotifera . 59 14. Acanthocephala, Gastrotricha & Nematomorpha . 60 15. Phylum Mollusca (Molluscs) . 67 16. Phyla Brachiopoda & Ectoprocta . 73 17. Phylum Annelida (Segmented Worms) . 74 18. Phyla Sipuncula . 78 19. Phylum Arthropoda (I): Trilobita, Myriopoda . 79 20. Phylum Arthropoda (II): Chelicerata . 81 21. Phylum Arthropods (III): Crustacea . 86 22. Phylum Arthropods (IV): Hexapoda . 90 23. Phyla Onycophora & Tardigrada . 97 24. Phylum Echinodermata (Echinoderms) . .104 25. Phyla Chaetognatha & Hemichordata . 108 26. Phylum Chordata (I): Lower Chordates & Agnatha . 109 27. Phylum Chordata (II): Chondrichthyes & Osteichthyes . 112 28. Phylum Chordata (III): Amphibia . 115 29. Phylum Chordata (IV): Reptilia . 118 30. Phylum Chordata (V): Aves . 121 31. Phylum Chordata (VI): Mammalia . 124 Lab Reports & Assignments Identifying Animal Phyla . 39 Identifying Common Freshwater Invertebrates . 42 Lab Report for Practical #1 . 43 Lab Report for Practical #2 . 62 Identification of Insect Orders . 96 Lab Report for Practical #3 .
    [Show full text]
  • Bivalve Biology - Glossary
    Bivalve Biology - Glossary Compiled by: Dale Leavitt Roger Williams University Bristol, RI A Aberrant: (L ab = from; erro = wonder) deviating from the usual type of its group; abnormal; wandering; straying; different Accessory plate: An extra, small, horny plate over the hinge area or siphons. Adapical: Toward shell apex along axis or slightly oblique to it. Adductor: (L ad = to; ducere = to lead) A muscle that draws a structure towards the medial line. The major muscles (usually two in number) of the bivalves, which are used to close the shell. Adductor scar: A small, circular impression on the inside of the valve marking the attachment point of an adductor muscle. Annulated: Marked with rings. Annulation or Annular ring: A growth increment in a tubular shell marked by regular constrictions (e.g., caecum). Anterior: (L ante = before) situated in front, in lower animals relatively nearer the head; At or towards the front or head end of a shell. Anterior extremity or margin: Front or head end of animal or shell. In gastropod shells it is the front or head end of the animal, i.e. the opposite end of the apex of the shell; in bivalves the anterior margin is on the opposite side of the ligament, i.e. where the foot protrudes. Apex, Apexes or Apices: (L apex = the tip, summit) the tip of the spire of a gastropod and generally consists of the embryonic shell. First-formed tip of the shell. The beginning or summit of the shell. The beginning or summit or the gastropod spire. The top or earliest formed part of shell-tip of the protoconch in univalves-the umbos, beaks or prodissoconch in bivalves.
    [Show full text]
  • Chapter Xii the Excretory System
    CHAPTER XII THE EXCRETORY SYSTEM Palle ANATOMY OF THE EXCRETORY Anatomy of the excretory system ______________ _____ 271 Histology ___ __ 273 SYSTEM Physiology_ 274 The waste products_______________ __ __ 276 The excretory organ of the oyster occupies an Osmoregulatlon______ _________________________________________________ 278 Bibliography __ __ ____ 279 indistinctly outlined triangular area on either side of the visceral mass. On the surface its location End products of bivalve catabolism are excreted is marked by light brownish pigmentation. The by the nephridia, pericardial glands, wandering organ consists of a central part which lies between phagocytes, and the mantle epithelium. The the pericardium and the adductor muscle and two urinary function, which is the principal activity branches or limbs which extend along both sides or of the excretory system, is performed by the paired the body. The right limb is slightly longer nephridia situated on either side of the visceral than its opposite member. Excretory tissues are mass near the heart. The pericardial glands, as found directly under the surface epithelium; they the name indicates, are located on the wall of the are surrounded by branchial vessels and numerous pericardium but in the oysters and some other blood sinuses. species are represented by special cells on the outer The relation between the different parts of the wall of the auricles. The wandering phagocytes excretory system, the heart, and the adductor may be found throughout the tissues of the visceral muscle is shown diagrammatically in figure 244. mass and the gills. They accumulate on the sur­ Each nephridium of a bivalve is bent into a face of the body by diapedesis and are discarded.
    [Show full text]
  • The Study of Nephridia and Genital Ducts Since 1895 (Continued)
    The Study of Nephridia and Genital Ducts since 1895 (continued). By Edwin S. Goodrich, F.B.S. Department of Zoology and Comparative Anatomy, University Museum, Oxford. With 100 Text-figures. CONTENTS. ARTHROPOD A, p. 303. Peripatiodea, with Segmental Coelomo- ducts mostly excretory, p. 305. Crustacea, possibly with remnants of Nephridia, p. 308. Summary, p. 317. Arachnida, p. 318. Chilopoda, Chilognatha, Symphyla, Insecta Hexa- poda, p. 320. General summary for Arthropoda, p. 322. MOLLUSCA, p. 324. Larval Protonephridia and Adult Coelomic Kidneys and Genital Ducts, p. 325. Relation of these to Germ- layers, p. 327. Their Interpretation as Coelmoducts, p. 329. Gastropoda, p. 328. Lamellibranchia, p. 330. Possible segmentation, Solenogastnes, Polyplaca- phora, Cephalopoda, p. 330. Development of Larval Protonephridia, p. 331. General summary for Mollusca, p. 334. Acanthocephala, p. 337. Priapulida, p. 339. Chaeto- gnatha, p. 342. Sipunculida, p. 344. Phoronida, p. 345. Brachiopoda, p. 349. Hemichordata, p. 349. Tunicata, p. 349. Echinodermata, p. 352. Vertebrata, p. 353. General Morphology of the Excretory Tubules and Genital Ducts of Craniata, p. 353. Protonephridia of the Acrania; paired Protonephridia, p. 358. The Unpaired Protonephridium of Hatschek, p. 364. Development of Hatschek's Protonephridium, p. 364. Development of the paired Protonephridia, p. 367. GENERAL CONCLUSION 373 SUMMARY ........... 378 Phylum Arthropoda. Before 1895 various authors (Leydig, Kowalevsky, Lankester, Sedgwick, Grobben, Weldon, Allen, and others) had compared the excretory organs of the Arthropoda to the segmental organs of the Annelida. These arthropod organs were then and are still now often called 'nephridia'. But the comparison was general and somewhat vague, since at that time the distinction between 4 rue nephridia and coelomoducts had not yet been pointed out.
    [Show full text]
  • Extrarenal Ammonia Excretion in the Terrestrial Pulmonate, Otala Lactea
    RICE UNIVERSITY EXTRARIME AMMONIA EXCRETION IN THE TERRESTRIAL PULMONATE, OTALA LACTEA Kemait Vincent Speeg, Jr* A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF ARTS Thesis Director’s signature: Houston, Texas May, 1966 ABSTHACT An extrarenal nitrogen product has been identified in two terrestrial snails.. Otala lactea and Helix asnersa. The nitrogen waste has been determined qualitatively to be ammonia;.; This ammonia which is excreted has also been measured quantitatively but no correlation could be found between the amount of ammonia excreted and the size of the snail; The ammonia excretion was circadian with the majority of the waste being excreted during the daytime* Ammonia was formed by lung tissue homogenates in the absence of added substrates, but this could not be found for blood* Urea and amino acids were added as substrate and urea was the only significant substrate for ammonia production* The levels of ammonia and urea concentration have been measured in dif¬ ferent tissues* Urease activity has been found and charac¬ terized* It was found to be non-bacterial in origin. An approximation was made of the percentage of total nitrogen excreted extrarenally and fotmd to be 38%. On the basis of this approximation it was thought to be a significant means of nitrogen excretion; A dramatic increase in blood pH was found for Otala lactea*. Helix asuersa. and Busycon«. This was fotmd to be due to the loss of physically dissolved carbon dioxide. Carbonic anhydrase activity was not found in Otala
    [Show full text]
  • The Pax Gene Family: Highlights from Cephalopods
    RESEARCH ARTICLE The Pax gene family: Highlights from cephalopods Sandra Navet1☯, Auxane Buresi1☯, SeÂbastien Baratte1,2, Aude Andouche1, Laure Bonnaud-Ponticelli1, Yann Bassaglia1,3* 1 UMR BOREA MNHN/CNRS7208/IRD207/UPMC/UCN/UA, MuseÂum National d'Histoire Naturelle, Sorbonne UniversiteÂs, Paris, France, 2 Univ. Paris Sorbonne-ESPE, Sorbonne UniversiteÂs, Paris, France, 3 Univ. Paris Est CreÂteil-Val de Marne, CreÂteil, France ☯ These authors contributed equally to this work. * [email protected] a1111111111 a1111111111 a1111111111 a1111111111 Abstract a1111111111 Pax genes play important roles in Metazoan development. Their evolution has been exten- sively studied but Lophotrochozoa are usually omitted. We addressed the question of Pax paralog diversity in Lophotrochozoa by a thorough review of available databases. The exis- tence of six Pax families (Pax1/9, Pax2/5/8, Pax3/7, Pax4/6, Paxβ, PoxNeuro) was con- OPEN ACCESS firmed and the lophotrochozoan Paxβ subfamily was further characterized. Contrary to the Citation: Navet S, Buresi A, Baratte S, Andouche A, pattern reported in chordates, the Pax2/5/8 family is devoid of homeodomain in Lophotro- Bonnaud-Ponticelli L, Bassaglia Y (2017) The Pax chozoa. Expression patterns of the three main pax classes (pax2/5/8, pax3/7, pax4/6) dur- gene family: Highlights from cephalopods. PLoS ONE 12(3): e0172719. doi:10.1371/journal. ing Sepia officinalis development showed that Pax roles taken as ancestral and common in pone.0172719 metazoans are modified in S. officinalis, most likely due to either the morphological specifici- Editor: Michael Schubert, Laboratoire de Biologie ties of cephalopods or to their direct development. Some expected expression patterns du DeÂveloppement de Villefranche-sur-Mer, were missing (e.g.
    [Show full text]
  • The Nephridium of Lumbricus and Its Blood- Supply; with Remarks on the Nephridia in Other Chsetopoda
    THE NEPHRIDITJM OF LUMBRIOUS. 293 The Nephridium of Lumbricus and its Blood- supply; with Remarks on the Nephridia in other Chsetopoda. By W, Blaxland Benham, D.Sc. (Loud.), Anatomical Department, Oxford. With Plates XXIII—XXV. THE nephridium of the common earthworm has recently been the subject of a contribution by Dr. Groehlich (20), in which he remarks on various statements made by Gegenbaur in his classical paper on the subject, published in 1853 (19), in which he corrected the then prevailing view that the seg- mentally arranged tubes were respiratory, and suggested their excretory function. As several of Goehlich's statements are at variance with those of Gegenbaur I was led to look into the details of the organ, and I then found that on those points the more recent writer was in error, and that Gegenbaur's description is much more nearly correct than Goehlich's. In fact, I have not very much to add to the description of the earlier writer beyond matters of histological detail, and more especially the blood-supply, which Professor Lankester suggested that I should work out. The work was carried out in the Zoological Laboratory of University College during the past eighteen months. 294 W. BLAXLAND BENHAM. CONTENTS OF PAPER. 1. Nomenclature of the parts of the nephridium, and the course of the various regions. 2. Histology of the various regions, and suggestions as to their function. 3. Comparison with the nephridium in other genera. 4. The nephrostome of Perichseta malamaniensis, n. sp., and other genera. 5. Circulation in the nephridium. 6. The nephridium of Arenicola.
    [Show full text]
  • Xxix. Problems of Nitrogen Catabolism in Invertebrates. Iii
    XXIX. PROBLEMS OF NITROGEN CATABOLISM IN INVERTEBRATES. III. ARGINASE IN THE INVERTEBRATES, WITH A NEW METHOD FOR ITS DETERMINATION. BY ERNEST BALDWIN1. From the Biochemical Department, Cambridge. (Received November 12th, 1934.) ARGINASE was discovered in mammalian liver by Kossel and Dakin [1904, 1, 2] who showed that the products of its action are ornithine and urea. Since that time the enzyme has attracted a great deal of interest from many points of view, but for present purposes it is sufficient, without going into the history of the subject, to point out that until very recently it was generally supposed that a small proportion of the urea excreted by mammals arises by the action of the liver arginase upon ingested arginine. Krebs and Henseleit, however, brought forward convincing evidence [1932] for supposing that the whole of the urea so excreted is elaborated by means of a cyclical mechanism involving arginase. In the meantime a generalisation ofthe greatest comparative importance was made by Clementi [1914; 1915], who pointed out that arginase could be detected in the livers of animals having a ureotelic metabolism, but not in cases where the metabolism is uricotelic in character. Manderscheid [1933] has extended the work of Krebs and Henseleit [1932] to other vertebrates and found the same cyclical system operating in those having the ureotelic type of metabolism, thus providing an explanation for the empirical rule enunciated by Clementi. The distribution of arginase among vertebrate tissues has been carefully studied by a number of workers [Edlbacher, 1915; Hunter and Dauphinee, 1924, 1, 2; Edlbacher and Bonem, 1925] but the invertebrates have received scant attention.
    [Show full text]