DOCSLIB.ORG

Some Recently Discovered Underwater Vibration Receptors in Invertebrates

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Some Recently Discovered Underwater Vibration Receptors in Invertebrates Some Contemporary Studiea in Marine Science, pp. 395-405 (1966) Harold Ba.mes, Ed. George Allen and Unwin Ltd., London SOME RECENTLY DISCOVERED UNDERWATER VIBRATION RECEPTORS IN INVERTEBRATES G. A. HORRIDGE Gatty Marine Laboratory and Department of Natural Hi~tory, University of St. Andrewa As every submarine commander knows, the best and almost the only underwater sense organs which are effective at long range utilize the excellent transmission of mechanical waves through water. And yet when the known examples of sense organs which are adapted to the detection of underwater vibrations were recently reviewed by Frings (1964), almost no substantiated examples could be found among marine invertebrates. Even in shallow water, large animals with excellent eyes spend about half of their time in dim moonlight or in the dark, and the range of vision falls off rapidly with depth, so that objects cannot be seen until they are relatively close. However, most invertebrates have eyes which are not well adapted for the detection of the direction and range of a moving prey. On the other hand, vibrations are set up in the water by any animal which propels itself along, as well as by waves at the surface or choppy water at a shore line. Therefore we can expect receptors for vibrations to be distributed ubiquitously through the marine groups, and to be used to detect prey or enemies, or to allow avoidance of environ­ mental sources of vibration. Perhaps one of the reasons why more examples of sense organs of this type are not known is because we ourselves have nothing similar, because the receptors are inconspicuous, and because the responses depending on them are usually not obvious escape reactions. However, in the last two or three years a number of examples have appeared in different phyla so that the general features of invertebrate underwater vibration receptors have now become apparent. Several of these examples have been discovered at St. Andrews. VIBRATION RECEPTORS Fingers of Leucothea (Ctenophora) This is an example of the vibration sense used by a carnivore in locating its prey. Leucothea ( = Eucharis) multicornis is a large fragile carnivorous Mediter­ ranean ctenophore which has numerous finger-like organs about 1 cm long scat- 396 G . .A. HORRIDGE tered over its external surface (Fig. lA). The epithelium of the finger tips is com­ posed of large glandular cells between which are sensory cells (Chun, 1880). Some of the sensory cells bear single straight stiff, non-motile cilia and these are receptors for any small displacement of the surrounding water. When a copepod or similar small planktonic animal swims within range, the finger shoots out with a sudden extension, caused by contraction of circular muscles which run through the mesogloea of the finger. The fingers extend to about 1 cm from a resting length of about half this value. The bottom of any dish in which the animal is supplied with copepods is soon littered with immobilized copepods. In 1844 Dr. Will, working in Trieste, claimed that the copepods were caught on small hooks on the ends of the fingers, but I have not yet seen this, and have not yet discovered how the Leucothe,a makes use of its victims. There are neither nematocysts nor similar organs on the fingers and the poison which kills the copepods presumably originates in the gland cells. A C B 2cm L---.J Fig. 1.-Leucothea ( = Etwharis) multicornis. A, the apical part of the ctenophore showing the finger organs scattered over the general surface. B, two fingers, one in the relaxed, and the other in the extended, position. C, the terminal epithelium of a finger showing the gland cells, thick pogs (function unknown) and a long non-motile cilium of the vibration sensory neurone. D, the base of a non-motile cilium with concentric lamellae which are surrounded by a mass of tubules (after Horridge, 1965a). The sense organs have been directly demonstrated to be the non-motile cilia in the following way. When an isolated finger is observed on a slide with a high power objective of long working distance, the cilia are found to be extremely sensitive mechanically. They cannot be touched without exciting the response. A glass needle mounted on the diaphragm of a loudspeaker, vibrated at a fre­ quency of 10 cycles/sec with a tip excursion of a few microns, can be manoeuvred into position near the cilium with a micromanipulator, but cannot be brought closer than about 100 µ, before the extension response of the whole finger is evoked. The structure of the sensory cilium itself is not peculiar, but the basal body and root is modified into a solid banded core which fits inside a spherical shell. The latter fits concentrically inside another spherical shell which is attached to a mass UNDERWATER VIBRATION RECEPTORS 397 of tubules filling the cytoplasm of the distal end of the cell (Fig. ID). It is clear that the non-motile cilium is mechanically coupled with the water so that any lateral movement of the water will be conveyed into a rocking movement of the basal body inside its spherical cup. This assumes that there is a plane of shearing between the concentric shells. A tentative theory of the mechanism is that shearing between the spherical shells causes current to flow through the mass of tubules which in turn depolarize the distal end of the cell membrane. The proximal end of the sensory neurone bears an axon which connects with other axons of the nerve net, which in turn are inferred to connect specifically with the circular muscle fibres causing extension. For further details, with electron micrographs, see Horridge (1965a). Tentacles of Pleurobrachia This is an example of a vibration receptor used as a detector of adverse environ­ mental conditions. The common St. Andrews ctenophore Pleurobrachia pileus, after being caught in a plankton net, usually swims downwards when brought into the laboratory. However, when the animals are carefully dipped out of the sea, and are handled . r ! ~ Fig. 2.-A, Pleurobrachia pilet,s turning over when vibration receptors of the tentacles and elsewhere are stimulated. B, Eutonina indicans turning to swim downwards and away from a source of low frequency vibration or ripples. Approximately natural size. gently without being lifted from the water, they commonly swim upwards. Speci­ mens which are swimming up respond by turning over and swimming downwards when one runs one's fingers to and fro over them in the tank, so causing ripples on the water surface. This stimulus causes a strong vibration which shakes the whole animal. The first sign of the responsei s a contraction of the two long tenta- 398 G. A. HORRIDGE cles, which normally trail in a relaxed fashion behind the animal. A vibrating needle, attached to a loud-speaker diaphragm, can stimulate a single tentacle when brought close to it. The response then starts as a contraction of the tentacle and spreads to the body of the Pleurobrachia, which changes the rate of its comb­ plates on one side relative to the other and turns over to swim downward (Fig. 2A). Isolated tentacles will respond by contracting and animals without tentacles will still invert when stimulated with the vibrating probe. The sense organ has not been identified. However, Hertwig, R. (1880, p. 326) mentioned that "Sinnesborsten" , similar to those of Leucothea, occur on the tenta­ cles of ctenophores. These are non-motile cilia which have not yet been found with the electron microscope on tentacles, but they may well turn out to be similar to the vibration receptors of Eucharis. The statolith in the ctenophore apical organ functions as a receptor of the direction of gravity because the weight of the statolith bears on the four groups of balancer cilia. These are strong groups of cilia which stand at the head of the ciliated grooves which in turn lead down to the comb-plates. Each beat of the balancer cilia sets off a wave of beats along the pair of ciliated grooves, which run from that balancer tuft and this wave travels along the comb-plates. In this way the balancer cilia are in control of the geotactic response (Horridge, 1965b). When a ctenophore turns over and swims downward in response to disturbance of the water, the sign of the response of the balancer cilia is reversed by excitation in the general nerve net. As a vibration receptor the statolith is not very effective. A large vibration in the water will jerk the statolith and then the balancer cilia respond, but usually all four respond together so that the additional waves in the comb-plates are of no consequence. Margin of Eutonina indicans (Hydromedusae) This is another example of the avoidance of surface ripples by a delicate plank­ tonic animal, which at the same time presents its mouth to a source of vibration. Eutonina is a hemispherical medusa about 3 cm. diameter, with a manubrium which reaches as far as the edge of the bell. Although the response is not typical of Hydromedusae the manubrium can be directed to any point on the subumbrellar surface where a stimulus is applied (Romanes, 1877). As was shown by making cuts, the manubrium is controlled by radial pathways which transmit inwards from the edge of the bell, as in Geryonia (Horridge, 1955). When a Eutonina is swimming in an upright position in a dish of sea water, it can be stimulated with a vibrating needle mounted on a loudspeaker diaphragm. The Eutonina turns over in a direction away from the stimulus and it swims downwards for several seconds or minutes (Fig. 2B). Like ctenophores, individuals of Eutonina which are damaged when collected from the sea usually swim down­ wards when brought into the laboratory, and upwardly swimming specimens must be dipped, not netted, out of the sea.
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]
  • Multiple Observations of Bigfin Squid (Magnapinna Sp.) in the Great
    PLOS ONE RESEARCH ARTICLE Multiple observations of Bigfin Squid (Magnapinna sp.) in the Great Australian Bight reveal distribution patterns, morphological characteristics, and rarely seen behaviour 1 2 1 3 Deborah OsterhageID *, Hugh MacIntosh , Franziska Althaus , Andrew Ross 1 CSIRO Oceans and Atmosphere, Commonwealth Scientific and Industrial Research Organisation, Hobart, a1111111111 Tasmania, Australia, 2 Museums Victoria, Melbourne, Victoria, Australia, 3 CSIRO Energy, Commonwealth a1111111111 Scientific and Industrial Research Organisation, Australian Resources Research Centre, Kensington, a1111111111 Western Australia, Australia a1111111111 a1111111111 * [email protected] Abstract OPEN ACCESS One of the most remarkable groups of deep-sea squids is the Magnapinnidae, known for Citation: Osterhage D, MacIntosh H, Althaus F, their large fins and strikingly long arm and tentacle filaments. Little is known of their biology Ross A (2020) Multiple observations of Bigfin and ecology as most specimens are damaged and juvenile, and in-situ sightings are sparse, Squid (Magnapinna sp.) in the Great Australian numbering around a dozen globally. As part of a recent large-scale research programme in Bight reveal distribution patterns, morphological the Great Australian Bight, Remotely Operated Vehicles and a towed camera system were characteristics, and rarely seen behaviour. PLoS ONE 15(11): e0241066. https://doi.org/10.1371/ deployed in depths of 946±3258 m resulting in five Magnapinna sp. sightings. These repre- journal.pone.0241066 sent the first records of Bigfin Squid in Australian waters, and more than double the known Editor: Johann Mourier, Institut de recherche pour records from the southern hemisphere, bolstering a hypothesis of cosmopolitan distribution. le developpement, FRANCE As most previous observations have been of single Magnapinna squid these multiple sight- Received: May 9, 2020 ings have been quite revealing, being found in close spatial and temporal proximity of each other.
    [Show full text]
  • Marine Invertebrate Field Guide
    Marine Invertebrate Field Guide Contents ANEMONES ....................................................................................................................................................................................... 2 AGGREGATING ANEMONE (ANTHOPLEURA ELEGANTISSIMA) ............................................................................................................................... 2 BROODING ANEMONE (EPIACTIS PROLIFERA) ................................................................................................................................................... 2 CHRISTMAS ANEMONE (URTICINA CRASSICORNIS) ............................................................................................................................................ 3 PLUMOSE ANEMONE (METRIDIUM SENILE) ..................................................................................................................................................... 3 BARNACLES ....................................................................................................................................................................................... 4 ACORN BARNACLE (BALANUS GLANDULA) ....................................................................................................................................................... 4 HAYSTACK BARNACLE (SEMIBALANUS CARIOSUS) .............................................................................................................................................. 4 CHITONS ...........................................................................................................................................................................................
    [Show full text]
  • Awareness, Prevention and Treatment of World-Wide Marine Stings and Bites
    Awareness, Prevention and Treatment of world-wide marine stings and bites Dr Peter Fenner Honorary Medical Officer, Surf Life Saving Australia International Life Saving Federation Medical/Rescue Conference Proceedings September 1997 Abstract The most common world-wide first aid treatment used by the average lifesaver/lifeguard is the treatment of marine envenomation, especially the treatment of jellyfish stings. It is important to use the correct first aid treatment for each type of envenomation. This study provides a simplified protocol for: - 1. Awareness of the geographical distribution and possibilities of envenomation enabling: - 2. Preventative strategies to reduce morbidity and mortality from marine envenomation 3. First aid treatment of marine envenomation by jellyfish or other marine animals This discussion is based on protocols developed for Surf Life Saving Australia and other first aid providers in Australia over the past ten years. Their success has been proven by a 30% reduction in the number of stings over the past 10 years (statistics from the author’s records). Information for this article has been taken from: - 1. Venomous and poisonous marine animals: a medical and biological handbook produced by Surf Life Saving Queensland 2. The global problem of cnidarian stinging. MD Thesis by the author for the University of London. Introduction The global problem of marine envenomation is not fully appreciated. Each year hundreds of deaths occur from poisoning (by ingestion or eating) or by envenomation (stinging by jellyfish, or biting by venomous marine animals). The morbidity is even greater with jellyfish stings world-wide being numbered in their millions. Each summer it is estimated that up to half a million stings occur on the east coast of the United States from the Portuguese man-o’-war (Physalia physalis).
    [Show full text]
  • Feeding-Dependent Tentacle Development in the Sea Anemone Nematostella Vectensis ✉ Aissam Ikmi 1,2 , Petrus J
    ARTICLE https://doi.org/10.1038/s41467-020-18133-0 OPEN Feeding-dependent tentacle development in the sea anemone Nematostella vectensis ✉ Aissam Ikmi 1,2 , Petrus J. Steenbergen1, Marie Anzo 1, Mason R. McMullen2,3, Anniek Stokkermans1, Lacey R. Ellington2 & Matthew C. Gibson2,4 In cnidarians, axial patterning is not restricted to embryogenesis but continues throughout a prolonged life history filled with unpredictable environmental changes. How this develop- 1234567890():,; mental capacity copes with fluctuations of food availability and whether it recapitulates embryonic mechanisms remain poorly understood. Here we utilize the tentacles of the sea anemone Nematostella vectensis as an experimental paradigm for developmental patterning across distinct life history stages. By analyzing over 1000 growing polyps, we find that tentacle progression is stereotyped and occurs in a feeding-dependent manner. Using a combination of genetic, cellular and molecular approaches, we demonstrate that the crosstalk between Target of Rapamycin (TOR) and Fibroblast growth factor receptor b (Fgfrb) signaling in ring muscles defines tentacle primordia in fed polyps. Interestingly, Fgfrb-dependent polarized growth is observed in polyp but not embryonic tentacle primordia. These findings show an unexpected plasticity of tentacle development, and link post-embryonic body patterning with food availability. 1 Developmental Biology Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany. 2 Stowers Institute for Medical Research, Kansas City, MO 64110,
    [Show full text]
  • Intercapsular Embryonic Development of the Big Fin Squid Sepioteuthis Lessoniana (Loliginidae)
    Indian Journal of Marine Sciences Vol. 31(2), June 2002, pp. 150-152 Short Communication Intercapsular embryonic development of the big fin squid Sepioteuthis lessoniana (Loliginidae) V. Deepak Samuel & Jamila Patterson* Suganthi Devadason Marine Research Institute, 44, Beach Road, Tuticorin – 628 001, Tamil Nadu, India ( E.mail : [email protected] ) Received 18 June 2001, revised 22 January 2002 The egg masses of big fin squid, Sepioteuthis lessoniana were collected from the wild and their intercapsular embryonic development was studied. The average incubation period of the egg varied between 18-20 days. The cleavage started on the first day and the mantle developed between third and fifth day. The yolk started decreasing eighth day onwards. The tentacles with the sucker primordia on the tip were prominent from tenth day. The yolk totally reduced between thirteenth and seventeenth day and the paralarvae hatched out on eighteenth day.The developmental stages of the embryo inside the capsules during the incubation period is understood. [ Key words: Sepioteuthis lessoniana , intercapsular development ] There are about 660 species of cephalopods in the the death of the embryo. Egg capsules were taken world oceans, of which less than hundred species are everyday to study the developmental stages of the of commercial importance. In the Indian seas, about growing embryos. Size of the egg capsules, eggs and 80 species of cephalopods exist but the main fishery is the embryos inside the eggs were recorded everyday contributed by only a dozen or so. Though they play till hatching. Various stages of development were ob- an important role in the economy of our country, their served and recorded as line drawings and photographs early life cycle and reproductive biology are not yet with the help of a light microscope.
    [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]
  • The Form and Function of the Hypertrophied Tentacle of Deep-Sea Jelly Atolla Spp
    The Form and Function of the Hypertrophied Tentacle of Deep-Sea Jelly Atolla spp. Alexis Walker, University of California Santa Cruz Mentors: Bruce Robison, Rob Sherlock, Kristine Walz, and Henk-Jan Hoving, George Matsumoto Summer 2011 Keywords: Atolla, tentacle, histology, SEM, hypertrophied ABSTRACT In situ observations and species collection via remotely operated vehicle, laboratory observations, and structural microscopy were used with the objective to shed light on the form and subsequently the function of the hypertrophied tentacle exhibited by some Atolla species. Based upon the density of nematocysts, length, movement, and ultrastructure of the hypertrophied tentacle, the function of the tentacle is likely reproductive, sensory, and/or utilized in food acquisition. INTRODUCTION The meso- and bathypelagic habitats are of the largest and least known on the planet. They are extreme environments, characterized by high atmospheric pressure, zero to low light levels, scarcity of food sources, and cold water that is low in oxygen content. Animals that live and even thrive in these habitats exhibit unique characteristics enabling them to survive in such seemingly inhospitable conditions. One such organism, the deep- sea medusa of the genus Atolla, trails a singular elongated tentacle, morphologically 1 distinct from the marginal tentacles. This structure, often referred to as a trailing or hypertrophied tentacle, is unique within the cnidarian phylum. Ernst Haeckel described the first species of this deep pelagic jelly, Atolla wyvillei, during the 1872-1876 HMS Challenger Expedition. In the subsequent 135 years, the genus Atolla has expanded to several species not yet genetically established, which have been observed in all of the worlds oceans (Russell 1970).
    [Show full text]
  • Unit One Introduction to Marine Invertebrates
    Unit One Introduction to Marine Invertebrates Activity 1 - Live Sea Animals . .3 Activity 2- Making an Undersea World . ..6 Objectives: To help students: Touch and identify common beach creatures such as sponges, jellyfishes, anemones, worms, crabs, barnacles, shrimps, amphipods, mollusks, sea stars, sea urchins and sea cucumbers (Activity 1). Understand the meaning of “invertebrate”: a soft-bodied animal without bones (Activity 1). Talk to a diver and/or marine biologist and observe their equipment (Activity 2). Decorate the classroom like an undersea world (Activity 2). Train “animals”(paper bag puppets) for an underwater circus (Activity 2). 1 . -- ., ., -<:.y:: ,.‘. :,” ; . .* . ‘. ..* 7 .*. ‘. ---=j.‘.’ : , ’ . UNIT ONE: Introduction to Marine Invertebrates. The ideal way to approach the study of invertebrates in all their diversity is through observation of live animals. All living things can be classified as belonging to either the plant Activity 1 kingdom orthe animal kingdom. Vertebrates and invertebrates are Live Sea Animals the two major subdivisions of the animal kingdom. Vertebrates are animals with backbones: humans, horses, elephants, mice, fishes, etc. Invertebrates are animals without backbones: sponges, sea stars,insects, worms, jellyfishes. Ninety-five percent of all animal species are invertebrates. There is a great assortment of colors, shapes and sizes among invertebrates found in Alaskan waters. Lacking backbones, they have various ways of supporting their bodies. Some,such as ane- 1 mones, rely on the water itself to give them shape and support. Sponges have a support system of Background: needlelike structures, which form In teaching children about marine entwining mesh. Crabs, an biology, nothing compares in shrimps,and beach hoppers have external skeletons, or “exoskele- excitement and value to the obser- vation of living creatures.
    [Show full text]
  • 1 What Is a Coral Reef?
    THE NATURENCYCLOPEDIA SERIES THE C L COLOR BOO · by Katherine Katherine Orr was born in New York, received a B.A. in Biology from Goucher College in 1972 and later an M .S. in Zoology at the University of Connecticut. She has spent many years both in the Caribbean and the Pacific on marine research projects and conducted numerous courses on awareness of the marine environment which is increasingly being threatened and destroyed by man. From 1982 until late 1986 she was attached to the Marine Biological Laboratory, Woods Hole, Mass. and now lives at Marathon Shores, Florida. THE CORAL REEF COLORING BOOK by Katherine Orr ~ Stemmer House Publishers 4 White Brook Rd. Gilsum, NH 03448 Copyright © 1988 Katherine Orr This book was first published by Macmillan Publishers Ltd., London and Basingstoke. It is derived from a project funded by World Wildlife - U.S. No part of this book may be used or reproduced in any manner whatsoever, electrical or mechanical, including xerography, microfilm, recording and photocopying, without written permission, except in the case of brief quotations in critical articles and reviews. The book may not be reproduced as a whole, or in substantial part, without pennission in writing from the publishers. Inquiries should be directed to Stemmer House Publishers, Inc. 4 White Brook Rd. Gilsum, NH 03448 A Barbara Holdridge book Printed and bound in the United States of America First printing 1988 Second printing 1990 Third printing 1992 Fourth printing 1995 Fifth printing 1999 Sixth printing 2003 Seventh printing 2007
    [Show full text]
  • BLANKET OCTOPUS (Tremoctopus Gracilis)
    NIGHT OCEAN Every night, in oceans across the globe, sensational alien-like creatures rise from the depths to feed. Welcome to the Night Ocean, where an entirely new cast of characters comes to life. Images © Magnus Lundgren / naturepl.com BLANKET OCTOPUS (Tremoctopus gracilis) Looking like something out of a science fiction movie, this blanket octopus is pictured in full opalescent display. Little is known about the rarely- encountered creature, which ranges from the depths of the dark zone to surface waters (where this female was seen in all her psychedelic glory). Anilao, Batangas the Philippines. ZOOPLANKTON Zooplankton is made up of a staggering diversity of animals – from single-celled organisms to the larvae of fish [1], anemones [2] and mollucs [3], as well as crustaceans [4], shellfish and jellies. 1 The zooplankton – in conjunction with hordes of photosynthetic phytoplankton, makes up the planktonic food supply upon which almost all oceanic organisms 2 depend. When the plankton rise, so do the deep ocean predators (pictured: a juvenile flying fish). The vertical migration influences our world more than many of us know. The daily movements of zooplankton help remove carbon from the atmosphere and surface waters, transporting it quickly and efficiently down into the ocean depths, where it can remain for centuries. Given that climate 3 change is already leading to ocean warming and acidification—a trend Every night an astonishing drama from the pages of science fiction. that is expected to accelerate— occurs in the world’s oceans: a The sheer biomass of the small carbon cycling provides the great vertical migration, in which drifting creatures – collectively impetus for much of today’s billions of organisms respond to known as zooplankton – renders zooplankton migration research.
    [Show full text]
  • Tales from the Cryptic: the Common Atlantic Octopus (Octopus Vulgaris)
    Tales from the Cryptic: The Common Atlantic Octopus (Octopus vulgaris) Kingdom-Animalia Phylum – Mollusca Class – Cephalopoda Order – Octopoda Suborder – Incirrina Family – Octopodidae Genus – Octopus Species – Octopus vulgaris photographed by Jim Lyle Cephalopods are one of the world’s most misunderstood classes of invertebrates. To many individuals they are slimy, creepy, and …downright ugly. This is why they are continuously featured in starring roles in horror movies about the abyss. But there are many more interesting aspects to these creatures than the heebie-jeebies that they seem to invoke in many people. Cephalopods, especially octopuses, are not only beautiful creatures, but more importantly, they are the most highly “intelligent” invertebrates in the sea. What is a Cephalopod? Cephalopods are a class of marine mollusks which include squid, octopuses, and chambered nautilus. They are distinguished by having a large head, extremely well developed eyes, and varying numbers of arms or tentacles, ranging from eight to one hundred, depending on the species. The name Cephalopoda is derived from the Greek words kephalo, meaning head, and pod, which means base or foot; accurately describing the appearance of the animals. What is an Octopus? An octopus has a bilaterally symmetrical body type with two eyes, 8 arms, and no tentacles. To many people, the terms ‘arms’ and ‘tentacles’ are synonymous, but in fact these body parts are distinctly different. A tentacle is a structure that may have a small club of suckers at the end, or it may also have hooks or be sucker-less. The tentacle functions as a sticky extender/retractor that can trap small planktonic organisms, whereas arms are entirely suckered or hooked ventrally, from base to tip.
    [Show full text]