DOCSLIB.ORG

A Test of Novel Function(S) for the Ink of Sea Hares

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
A Test of Novel Function(S) for the Ink of Sea Hares Journal of Experimental Marine Biology and Ecology, L 234 (1999) 185±197 A test of novel function(s) for the ink of sea hares Thomas H. Carefoota,* , Steven C. Pennings b , Jean Paul Danko a aDepartment of Zoology, University of British Columbia, 6270 University Blvd, Vancouver, BC V6T 1Z4, Canada bMarine Institute, University of Georgia, Sapelo Island, GA 31327, USA Received 12 March 1998; received in revised form 20 August 1998; accepted 21 August 1998 Abstract Most sea hares (Opisthobranchia: Anaspidea) release a purple ink when physically disturbed. The ink has been hypothesized to function to excrete unwanted byproducts of metabolism, as a smoke screen, as an anti-feedant, and as a warning signal. We tested two additional potential functions: that ink is a metabolic depressant and/or a noxious or adversive sensory stimulus. When exposed to realistic concentrations of ink from Aplysia dactylomela (Rang), none of ®ve invertebrate species (including A. dactylomela) or two ®sh species signi®cantly altered their oxygen uptake, and neither of two crab species signi®cantly altered their heart and/or scaphog- nathite beat rates, suggesting that ink does not function as a metabolic depressant. In contrast, although A. dactylomela did not display strong behavioural responses to ink, behaviour of seven other invertebrates and both ®sh species was strongly affected by ink, supporting our hypothesis that the ink functions as an irritant. Observed behavioural changes included bristle erection by ®reworms, increased mucus production by an opisthobranch, reduced feeding behaviour, increased grooming behaviour, and temporary pauses in heart and scaphognathite beating by crabs, reduced and increased activity by cryptic and exposed sea urchin species, respectively, and rapid swimming by ®sh. Similar behavioural changes by potential predators would likely lead to reduced predation rates on Aplysia spp. in the ®eld. Our conclusion that ink functions as a sensory irritant is not incompatible with other hypotheses for the function of ink. 1999 Elsevier Science B.V. All rights reserved. Keywords: Sea hare; Aplysia; Ink; Defensive function; Opisthobranchia 1. Introduction Most sea hares (speci®cally, Aplysia spp., but including closely related Dolabella spp. *Corresponding author. Tel.: 11-604-8224357; e-mail: [email protected] 0022-0981/99/$ ± see front matter 1999 Elsevier Science B.V. All rights reserved. PII: S0022-0981(98)00153-1 186 T.H. Carefoot et al. / J. Exp. Mar. Biol. Ecol. 234 (1999) 185 ±197 and Stylocheilus spp.) (Opisthobranchia:Anaspidea) produce a purple-coloured ink from special glands in the lower surface of the mantle cavity. The primary organic constituent of the ink is aplysioviolin, a violet-colored ester derived from phycoerythrobilin, a pigment of red seaweeds eaten as food (Chapman and Fox, 1967). If these seaweeds are omitted from the diet, an animal becomes facultatively de-inked. On its release, the ink consists mostly of water and other volatile substances with less than 2% dry mass organic substances and 5% minerals (Flury, 1915). Ink volume in the glands has never been measured, but even in a large animal could comprise no more than a few milliliters (personal observation). Release is accompanied by varying degrees of mantle contrac- tions and parapodial ¯appings which, depending upon their magnitude and the amount of mucus released with the ink, will cause the ink to hang in a heavy purple cloud in the water near the animal or be dispersed more widely and quickly. Release of ink is a high-threshold, all-or-none response (Carew and Kandel, 1977; Shapiro et al., 1979; Byrne, 1981). In the laboratory it can often, but not always, be induced by rough handling, pin pricks, mild electric shocks, separation of copulating individuals, or the like. In the ®eld, observation of ink release in the absence of human stimulation is extremely rare (Kupfermann and Carew, 1974; our personal observation). Only Willan (1979) has reported seeing ink released in response to actions of another animal in the ®eld, in this case an Aplysia dactylomela apparently under attack from the star®sh Coscinasterias calamaria. Indeed, predators of Aplysia species are essentially unknown (for review see Carefoot, 1987; Pennings, 1990a). Apart from ink as a possible ®rst line of defense, sea hares possess a toxic opaline-gland secretion (Flury, 1915; Ando, 1952) and a broad spectrum of algal-derived toxins in the skin and digestive gland (for review see Carefoot, 1987). Aplysia dactylomela alone sequesters some 20 different secondary metabolites from its algal diet, any or all of which could be defensive in function. However, despite the depth and diversity of this chemical repertoire, unequivocal demonstration of a defensive function for any component is mostly lacking (Beeman, 1961; Ambrose et al., 1979; DiMatteo, 1981, 1982; Pennings, 1990b; Paul and Pennings, 1991; Pennings and Paul, 1993; Pennings, 1994; Nolen et al., 1995). Several hypotheses have been proposed for the function of ink in Aplysia and related sea hares: (1) it acts as a method to rid the animal of unwanted bile pigments consumed in its diet (Chapman and Fox, 1967), (2) it acts as a `smoke-screen' on release, thus shielding the sea hare from visual predators (Eales, 1921; Halstead, 1965; Hyman, 1967; Carew and Kandel, 1977), (3) it is distasteful, causing the sea hare to be unpalatable and thus acting as an `anti-feedant' (Beeman, 1961; DiMatteo, 1981, 1982; Pennings, 1994; Nolen et al., 1995), (4) it functions as a warning to would-be predators of the sea hare's other toxic properties (Ambrose et al., 1979), and (5) it acts in some manner as an alarm signal to conspeci®cs (Fiorito and Gherardi, 1990; Stopfer et al., 1993; this last idea is consistent with the notion that cephalopod ink may function as an intraspeci®c alarm substance: Gilly and Lucero, 1992, and others). However, based on the observation of Willan (1979) that locomotory movement of the star®sh Coscinsterias calamaria was retarded by contact with sea-hare ink, additional hypotheses of metabolic depressant- effect or chemosensory desensitization could be added to the list. This last idea is reminiscent of the observation of MacGinitie and MacGinitie (1968) that the `real effect' of octopus ink is to anaesthetize the chemosensory abilities of ®sh predators. T.H. Carefoot et al. / J. Exp. Mar. Biol. Ecol. 234 (1999) 185 ±197 187 In this paper we test the hypothesis that ink has a metabolic inhibitory effect on other organisms. We have long noticed that Aplysia spp. exposed to their own ink appear largely unaffected if the duration of exposure is relatively short and ink concentration not excessive, while other animals such as crabs and ®sh can be seriously and often fatally affected by the same exposure. In addition, we test another hypothesis that the ink functions as a chemosensory irritant to ward off attacks by potential predators. This hypothesis is based on our observations that crabs often attempt to groom themselves if they contact ink and mucus from Aplysia spp. (see also DiMatteo, 1982). We hypothesized that ink might act to protect the sea hares at a distance (i.e. without direct contact and taste) by irritating potential predators enough that they would leave the vicinity of the sea hare. To test these hypotheses, we measured the effects of different concentrations of sea-hare ink on the behaviour and metabolism of Aplysia dactylomela (Rang) and on a diversity of sympatric taxa which might be naturally exposed to the ink. 2. Methods Aplysia dactylomela is a large (to ca. 500 g) circumtropical sea hare. It is active at night, feeding primarily on red seaweeds. The behaviour and ecology of A. dactylomela are described in Carefoot (1989). Aplysia dactylomela of 30±500 g live mass were collected from the shallow backreef area near the Discovery Bay Marine Laboratory, Jamaica (188309N, 778209W) and kept in a ¯ow-through seawater system with an abundant supply of red algae as food. Additionally, several species of other invertebrates and ®sh were collected from the Aplysia habitat and kept in the laboratory seawater tanks (the predatory ®reworm Hermodice carunculata Hartman, green clinging crab Mithrax sculptus Lamarck, swimming crab Portunus sebae Latrielle, sea urchins Echinometra lucunter Linnaeus and Lytechinus variegatus Lamarck, opisthobranch Tridachia crispata Younge & Nicholas, predatory puffer Diodon holocanthus Linnaeus, and the predatory goby Gnatholepis thompsoni Jordan. Our goal was not to identify particular Aplysia predators as such, since these are not well known, but rather to assess the effects of ink on a wide taxonomic range of animals. Consequently, test species were chosen based on abun- dance, taxonomic diversity, and ease of collection and maintenance in the laboratory. However, we note that the majority of the taxa selected (®sh, crabs, polychaetes) include species that are predatory upon soft-bodied invertebrates, and thus represent taxa that include potential predators of Aplysia. The smaller Aplysia (30±60 g live mass) were used in the respirometry and behaviour experiments, while the larger ones were maintained as ink donors. 2.1. Collection of ink for testing We collected ink by carefully lifting individual Aplysia out of the water and allowing excess water to drain, then gently massaging the surface of the mantle in the vicinity of the ink gland, shell, and gill. This procedure stimulated animals to release ink, which was collected in a small beaker. Several animals were usually de-inked at one time to provide suf®cient ink for a number of experiments. The ink was kept at 58C between 188 T.H. Carefoot et al. / J. Exp. Mar. Biol. Ecol. 234 (1999) 185 ±197 experiments to minimize any potential `aging' effects (ink was typically used in experiments within an hour of collection, and was never kept longer than 6 h). After an animal was de-inked it was allowed to rest and feed for several days before ink was collected from it again.
Load more

Recommended publications
  • [Oceanography and Marine Biology - an Annual Review] R. N
    OCEANOGRAPHY and MARINE BIOLOGY AN ANNUAL REVIEW Volume 44 7044_C000.fm Page ii Tuesday, April 25, 2006 1:51 PM OCEANOGRAPHY and MARINE BIOLOGY AN ANNUAL REVIEW Volume 44 Editors R.N. Gibson Scottish Association for Marine Science The Dunstaffnage Marine Laboratory Oban, Argyll, Scotland [email protected] R.J.A. Atkinson University Marine Biology Station Millport University of London Isle of Cumbrae, Scotland [email protected] J.D.M. Gordon Scottish Association for Marine Science The Dunstaffnage Marine Laboratory Oban, Argyll, Scotland [email protected] Founded by Harold Barnes Boca Raton London New York CRC is an imprint of the Taylor & Francis Group, an informa business CRC Press Taylor & Francis Group 6000 Broken Sound Parkway NW, Suite 300 Boca Raton, FL 33487-2742 © 2006 by R.N. Gibson, R.J.A. Atkinson and J.D.M. Gordon CRC Press is an imprint of Taylor & Francis Group, an Informa business No claim to original U.S. Government works Printed in the United States of America on acid-free paper 10 9 8 7 6 5 4 3 2 1 International Standard Book Number-10: 0-8493-7044-2 (Hardcover) International Standard Book Number-13: 978-0-8493-7044-1 (Hardcover) International Standard Serial Number: 0078-3218 This book contains information obtained from authentic and highly regarded sources. Reprinted material is quoted with permission, and sources are indicated. A wide variety of references are listed. Reasonable efforts have been made to publish reliable data and information, but the author and the publisher cannot assume responsibility for the valid- ity of all materials or for the consequences of their use.
    [Show full text]
  • Lipopeptides from Cyanobacteria: Structure and Role in a Trophic Cascade
    Lipopeptides from Cyanobacteria : structure and role in a trophic cascade Louis Bornancin To cite this version: Louis Bornancin. Lipopeptides from Cyanobacteria : structure and role in a trophic cascade. Other. Université Montpellier, 2016. English. NNT : 2016MONTT202. tel-02478948 HAL Id: tel-02478948 https://tel.archives-ouvertes.fr/tel-02478948 Submitted on 14 Feb 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. Délivré par Université de Montpellier Préparée au sein de l’école doctorale Sciences Chimiques Balard Et de l’unité de recherche Centre de Recherche Insulaire et Observatoire de l’Environnement (USR CNRS-EPHE-UPVD 3278) Spécialité : Ingénierie des Biomolécules Présentée par Louis BORNANCIN Lipopeptides from Cyanobacteria : Structure and Role in a Trophic Cascade Soutenue le 11 octobre 2016 devant le jury composé de Monsieur Ali AL-MOURABIT, DR CNRS, Rapporteur Institut de Chimie des Substances Naturelles Monsieur Gérald CULIOLI, MCF, Rapporteur Université de Toulon Madame Martine HOSSAERT-MCKEY, DR CNRS, Examinatrice, Centre d’Écologie
    [Show full text]
  • Of the Sea Hare Aplysia Dactylomela
    Marine Biology (1998) 130: 389±396 Ó Springer-Verlag 1998 T. H. Carefoot á M. Harris á B. E. Taylor D. Donovan á D. Karentz Mycosporine-like amino acids: possible UV protection in eggs of the sea hare Aplysia dactylomela Received: 13 May 1997 / Accepted: 27 June 1997 Abstract We investigated mycosporine amino acid twice as often. The UV-treated adults produced spawn _ (MAA) involvement as protective sunscreens in spawn with signi®cantly higher V O2 s and their embryos devel- of the sea hare Aplysia dactylomela to determine if adult oped to hatching sooner. The only signi®cant eect of diet and ultraviolet (UV) exposure aected the UV UV exposure of the spawn was to reduce the percentage sensitivity of developing embryos. Adults were fed a red of veligers hatching from 71 to 50%. There was no sig- alga rich in MAAs (Acanthophora spicifera) or a green ni®cant eect on hatching time or size of the veligers at alga poor in MAAs (Ulva lactuca). Adults on each diet hatching, nor on number of eggs per capsule. were exposed for 2 wk to ambient solar irradiance with two types of acrylic ®lters; one allowed exposure to wavelengths >275 nm (designated UV) and one to Introduction wavelengths only >410 nm (designated NOUV). Spawn from each adult group was likewise treated with UV or Ultraviolet radiation in both the A (320 to 400 nm) and NOUV and monitored during development for dier- B (280 to 320 nm) portions of the spectrum has broad- ences in mortality and metabolic rate (measured as ox- ranging deleterious eects on marine organisms.
    [Show full text]
  • An Overview of the Fossil Record of Pteropoda (Mollusca, Gastropoda, Heterobranchia)
    Cainozoic Research, 17(1), pp. 3-10 June 2017 3 An overview of the fossil record of Pteropoda (Mollusca, Gastropoda, Heterobranchia) Arie W. Janssen1 & Katja T.C.A. Peijnenburg2, 3 1 Naturalis Biodiversity Center, Marine Biodiversity, Fossil Mollusca, P.O. Box 9517, 2300 RA Leiden, The Nether­ lands; [email protected] 2 Naturalis Biodiversity Center, Marine Biodiversity, P.O. Box 9517, 2300 RA Leiden, The Netherlands; Katja.Peijnen­ [email protected] 3 Institute for Biodiversity and Ecosystem Dynamics (IBED), University of Amsterdam, P.O. Box 94248, 1090 GE Am­ sterdam, The Netherlands. Manuscript received 23 January 2017, revised version accepted 14 March 2017 Based on the literature and on a massive collection of material, the fossil record of the Pteropoda, an important group of heterobranch marine, holoplanktic gastropods occurring from the late Cretaceous onwards, is broadly outlined. The vertical distribution of genera is illustrated in a range chart. KEY WORDS: Pteropoda, Euthecosomata, Pseudothecosomata, Gymnosomata, fossil record Introduction Thecosomata Mesozoic Much current research focusses on holoplanktic gastro- pods, in particular on the shelled pteropods since they The sister group of pteropods is now considered to belong are proposed as potential bioindicators of the effects of to Anaspidea, a group of heterobranch gastropods, based ocean acidification e.g.( Bednaršek et al., 2016). This on molecular evidence (Klussmann-Kolb & Dinapoli, has also led to increased interest in delimiting spe- 2006; Zapata et al., 2014). The first known species of cies boundaries and distribution patterns of pteropods pteropods in the fossil record belong to the Limacinidae, (e.g. Maas et al., 2013; Burridge et al., 2015; 2016a) and are characterised by sinistrally coiled, aragonitic and resolving their evolutionary history using molecu- shells.
    [Show full text]
  • Biodiversity Journal, 2020, 11 (4): 861–870
    Biodiversity Journal, 2020, 11 (4): 861–870 https://doi.org/10.31396/Biodiv.Jour.2020.11.4.861.870 The biodiversity of the marine Heterobranchia fauna along the central-eastern coast of Sicily, Ionian Sea Andrea Lombardo* & Giuliana Marletta Department of Biological, Geological and Environmental Sciences - Section of Animal Biology, University of Catania, via Androne 81, 95124 Catania, Italy *Corresponding author: [email protected] ABSTRACT The first updated list of the marine Heterobranchia for the central-eastern coast of Sicily (Italy) is here reported. This study was carried out, through a total of 271 scuba dives, from 2017 to the beginning of 2020 in four sites located along the Ionian coasts of Sicily: Catania, Aci Trezza, Santa Maria La Scala and Santa Tecla. Through a photographic data collection, 95 taxa, representing 17.27% of all Mediterranean marine Heterobranchia, were reported. The order with the highest number of found species was that of Nudibranchia. Among the study areas, Catania, Santa Maria La Scala and Santa Tecla had not a remarkable difference in the number of species, while Aci Trezza had the lowest number of species. Moreover, among the 95 taxa, four species considered rare and six non-indigenous species have been recorded. Since the presence of a high diversity of sea slugs in a relatively small area, the central-eastern coast of Sicily could be considered a zone of high biodiversity for the marine Heterobranchia fauna. KEY WORDS diversity; marine Heterobranchia; Mediterranean Sea; sea slugs; species list. Received 08.07.2020; accepted 08.10.2020; published online 20.11.2020 INTRODUCTION more researches were carried out (Cattaneo Vietti & Chemello, 1987).
    [Show full text]
  • As Fast As a Hare: Colonization of the Heterobranch Aplysia Dactylomela (Mollusca: Gastropoda: Anaspidea) Into the Western Mediterranean Sea
    Cah. Biol. Mar. (2017) 58 : 341-345 DOI: 10.21411/CBM.A.97547B71 As fast as a hare: colonization of the heterobranch Aplysia dactylomela (Mollusca: Gastropoda: Anaspidea) into the western Mediterranean Sea Juan MOLES1,2, Guillem MAS2, Irene FIGUEROA2, Robert FERNÁNDEZ-VILERT2, Xavier SALVADOR2 and Joan GIMÉNEZ2,3 (1) Department of Evolutionary Biology, Ecology, and Environmental Sciences and Biodiversity Research Institute (IrBIO), University of Barcelona, Av. Diagonal 645, 08028 Barcelona, Catalonia, Spain E-mail: [email protected] (2) Catalan Opisthobranch Research Group (GROC), Mas Castellar, 17773 Pontós, Catalonia, Spain (3) Department of Conservation Biology, Estación Biológica de Doñana (EBD-CSIC), Americo Vespucio 26 Isla Cartuja, 42092 Seville, Andalucía, Spain Abstract: The marine cryptogenic species Aplysia dactylomela was recorded in the Mediterranean Sea in 2002 for the first time. Since then, this species has rapidly colonized the eastern Mediterranean, successfully establishing stable populations in the area. Aplysia dactylomela is a heterobranch mollusc found in the Atlantic Ocean, and commonly known as the spotted sea hare. This species is a voracious herbivorous with generalist feeding habits, possessing efficient chemical defence strategies. These facts probably promoted the acclimatation of this species in the Mediterranean ecosystems. Here, we report three new records of this species in the Balearic Islands and Catalan coast (NE Spain). This data was available due to the use of citizen science platforms such as GROC (Catalan Opisthobranch Research Group). These are the first records of this species in Spain and the third in the western Mediterranean Sea, thus reinforcing the efficient, fast, and progressive colonization ability of this sea hare.
    [Show full text]
  • Diversity and Distribution of Molluscs in the Intertidal Zone of Nglambor Beach, Gunung Kidul, Yogyakarta
    BIO Web of Conferences 33, 01002 (2021) https://doi.org/10.1051/bioconf/20213301002 ICAVESS 2021 Diversity and Distribution of Molluscs in the Intertidal Zone of Nglambor Beach, Gunung Kidul, Yogyakarta Yunita Fera Rahmawati1*, Rizka Apriani Putri1, Tatag Bagus Putra Prakarsa1, Milade Annisa Muflihaini1, and Yoga Putra Aliyani1 1Department of Biology Education, Faculty of Mathematics and Natural Sciences, Universitas Negeri Yogyakarta. Jl. Colombo No. 1 Karang Malang, Yogyakarta. Tel.: +62-586168 Abstract. The intertidal zone is the area between the highest and lowest tides, which represents the transition from ocean conditions to land conditions. This study aimed to determine the diversity and distribution of mollusks that exist along the intertidal zone of Nglambor Beach, between August and November 2020. Observations of all molluscs were carried out at two random stations using 10 plots measuring 1 x 1 m2 with 5 meters. A total of two classes of Mollusca (Gastropod and Bivalvia) belonging to twelve families and 19 species were found from upper to lower an intertidal zone. The upper intertidal zone was recorded to have the highest diversity and an evenness index (Shannon-Wiener diversity index: H '= 2.524 and Pielou evenness index: J' = 0.932) compared to the middle and lower zones. It can be concluding that the diversity index in the study location is categorized as medium and its evenness is high. Thais hippocastanum is the most dominant species found in the upper and middle zones, while Thais tissoti dominates in the lower zone. This research contributed to a preliminary checklist on molluscs, which will support a baseline study on the intertidal in future.
    [Show full text]
  • Phylogeny of the Sea Hares in the Aplysia Clade Based on Mitochondrial DNA Sequence Data
    Lawrence Berkeley National Laboratory Lawrence Berkeley National Laboratory Title Phylogeny of the sea hares in the aplysia clade based on mitochondrial DNA sequence data Permalink https://escholarship.org/uc/item/0fv9g804 Authors Medina, Monica Collins, Timothy Walsh, Patrick J. Publication Date 2004-02-20 Peer reviewed eScholarship.org Powered by the California Digital Library University of California PHYLOGENY OF THE SEA HARES IN THE APLYSIA CLADE BASED ON 1,2 MITOCHONDRIAL DNA SEQUENCE DATA MÓNICA MEDINA , TIMOTHY 3 1 COLLINS , AND PATRICK J. WALSH 1 Rosenstiel School of Marine and Atmospheric Science, Division of Marine Biology and Fisheries, University of Miami, 4600 Rickenbacker Causeway, Miami, FL 33149 USA. RUNNING HEAD: Aplysia mitochondrial phylogeny 2 present address: Joint Genome Institute, 2800 Mitchell Drive B400, Walnut Creek, CA 94598 e-mail: [email protected] phone: (925)296-5633 fax: (925)296-5666 3 Department of Biological Sciences, Florida International University, University Park, Miami, FL 33199 USA ABSTRACT Sea hare species within the Aplysia clade are distributed worldwide. Their phylogenetic and biogeographic relationships are, however, still poorly known. New molecular evidence is presented from a portion of the mitochondrial cytochrome oxidase c subunit 1 gene (cox1) that improves our understanding of the phylogeny of the group. Based on these data a preliminary discussion of the present distribution of sea hares in a biogeographic context is put forward. Our findings are consistent with only some aspects of the current taxonomy and nomenclatural changes are proposed. The first, is the use of a rank free classification for the different Aplysia clades and subclades as opposed to previously used genus and subgenus affiliations.
    [Show full text]
  • Utility of H3-Genesequences for Phylogenetic Reconstruction – a Case Study of Heterobranch Gastropoda –*
    Bonner zoologische Beiträge Band 55 (2006) Heft 3/4 Seiten 191–202 Bonn, November 2007 Utility of H3-Genesequences for phylogenetic reconstruction – a case study of heterobranch Gastropoda –* Angela DINAPOLI1), Ceyhun TAMER1), Susanne FRANSSEN1), Lisha NADUVILEZHATH1) & Annette KLUSSMANN-KOLB1) 1)Department of Ecology, Evolution and Diversity – Phylogeny and Systematics, J. W. Goethe-University, Frankfurt am Main, Germany *Paper presented to the 2nd International Workshop on Opisthobranchia, ZFMK, Bonn, Germany, September 20th to 22nd, 2006 Abstract. In the present study we assessed the utility of H3-Genesequences for phylogenetic reconstruction of the He- terobranchia (Mollusca, Gastropoda). Therefore histone H3 data were collected for 49 species including most of the ma- jor groups. The sequence alignment provided a total of 246 sites of which 105 were variable and 96 parsimony informa- tive. Twenty-four (of 82) first base positions were variable as were 78 of the third base positions but only 3 of the se- cond base positions. H3 analyses showed a high codon usage bias. The consistency index was low (0,210) and a substitution saturation was observed in the 3r d codon position. The alignment with the translation of the H3 DNA sequences to amino-acid sequences had no sites that were parsimony-informative within the Heterobranchia. Phylogenetic trees were reconstructed using maximum parsimony, maximum likelihood and Bayesian methodologies. Nodilittorina unifasciata was used as outgroup. The resolution of the deeper nodes was limited in this molecular study. The data themselves were not sufficient to clar- ify phylogenetic relationships within Heterobranchia. Neither the monophyly of the Euthyneura nor a step-by-step evo- lution by the “basal” groups was supported.
    [Show full text]
  • The Embryonic Life History of the Tropical Sea Hare Stylocheilus Striatus (Gastropoda: Opisthobranchia) Under Ambient and Elevated Ocean Temperatures
    The embryonic life history of the tropical sea hare Stylocheilus striatus (Gastropoda: Opisthobranchia) under ambient and elevated ocean temperatures Rael Horwitz1,2, Matthew D. Jackson3 and Suzanne C. Mills1,2 1 Paris Sciences et Lettres (PSL) Research University: École Pratique des Hautes Études (EPHE)-Université de Perpignan Via Domitia (UPVD)-Centre National de la Recherche Scientifique (CNRS), Unité de Service et de Recherche 3278 Centre de Recherches Insulaires et Observatoire de l'Environnement (CRIOBE), Papetoai, Moorea, French Polynesia 2 Laboratoire d'Excellence ``CORAIL'', Moorea, French Polynesia 3 School of Geography and Environmental Sciences, Ulster University, Coleraine, UK ABSTRACT Ocean warming represents a major threat to marine biota worldwide, and forecasting ecological ramifications is a high priority as atmospheric carbon dioxide (CO2) emis- sions continue to rise. Fitness of marine species relies critically on early developmental and reproductive stages, but their sensitivity to environmental stressors may be a bottleneck in future warming oceans. The present study focuses on the tropical sea hare, Stylocheilus striatus (Gastropoda: Opisthobranchia), a common species found throughout the Indo-West Pacific and Atlantic Oceans. Its ecological importance is well-established, particularly as a specialist grazer of the toxic cyanobacterium, Lyngbya majuscula. Although many aspects of its biology and ecology are well-known, description of its early developmental stages is lacking. First, a detailed account of this species' life history is described, including reproductive behavior, egg mass characteristics and embryonic development phases. Key developmental features are then compared between embryos developed in present-day (ambient) and predicted end-of-century elevated ocean temperatures (C3 ◦C). Results showed developmental stages of embryos reared at ambient temperature were typical of other opisthobranch Submitted 17 October 2016 species, with hatching of planktotrophic veligers occurring 4.5 days post-oviposition.
    [Show full text]
  • Species Report Bursatella Leachii (Ragged Sea Hare)
    Mediterranean invasive species factsheet www.iucn-medmis.org Species report Bursatella leachii (Ragged sea hare) AFFILIATION MOLLUSCS SCIENTIFIC NAME AND COMMON NAME REPORTS Bursatella leachii 17 Key Identifying Features This large sea slug can reach more than 10 cm in length. The body has numerous long, branching, white papillae (finger-like outgrowths) that give the animal its ragged appearance. A key distinctive feature is its grey-brown body with dark brown blotches on the white papillae and bright blue eyespots scattered over the body. The head bears four tentacles: two olfactory tentacles originating on the dorsal part of the head resembling long ears, and two oral tentacles, similar in shape, near the mouth. Adults lack an external shell. 2013-2021 © IUCN Centre for Mediterranean Cooperation. More info: www.iucn-medmis.org Pag. 1/5 Mediterranean invasive species factsheet www.iucn-medmis.org Identification and Habitat Other species that look similar This species occurs most commonly in shallow, sheltered waters, often on sandy or muddy bottoms with Caulerpa prolifera, well camouflaged in seagrass beds, and occasionally in harbour environments. If disturbed or touched it can release purple ink. Its behaviour varies with the time of day, as it is more active during the daytime and hides at night. In the early morning sea hares are found clustered together in groups of 8–12 individuals, and they disperse to feed on algal films during the day. They reassemble again at night. Reproduction Bursatella leachii is a hermaphroditic species with a very fast life cycle and continuous reproduction. When mating, one individual acts as a male and crawls onto another one to fertilize it.
    [Show full text]
  • Research and Discoveries the Revolution of Science Through Scuba
    Smithsonian Institution Scholarly Press smithsonian contributions to the marine sciences • number 39 Smithsonian Institution Scholarly Press Research and Discoveries The Revolution of Science through Scuba Edited by Michael A. Lang, Roberta L. Marinelli, Susan J. Roberts, and Phillip R. Taylor SERIES PUBLICATIONS OF THE SMITHSONIAN INSTITUTION Emphasis upon publication as a means of “diffusing knowledge” was expressed by the first Secretary of the Smithsonian. In his formal plan for the Institution, Joseph Henry outlined a program that included the following statement: “It is proposed to publish a series of reports, giving an account of the new discoveries in science, and of the changes made from year to year in all branches of knowledge.” This theme of basic research has been adhered to through the years by thousands of titles issued in series publications under the Smithsonian imprint, com- mencing with Smithsonian Contributions to Knowledge in 1848 and continuing with the following active series: Smithsonian Contributions to Anthropology Smithsonian Contributions to Botany Smithsonian Contributions to History and Technology Smithsonian Contributions to the Marine Sciences Smithsonian Contributions to Museum Conservation Smithsonian Contributions to Paleobiology Smithsonian Contributions to Zoology In these series, the Institution publishes small papers and full-scale monographs that report on the research and collections of its various museums and bureaus. The Smithsonian Contributions Series are distributed via mailing lists to libraries, universities, and similar institu- tions throughout the world. Manuscripts submitted for series publication are received by the Smithsonian Institution Scholarly Press from authors with direct affilia- tion with the various Smithsonian museums or bureaus and are subject to peer review and review for compliance with manuscript preparation guidelines.
    [Show full text]