مرکزی صفحہ Ocean: The Definitive Visual Guide
آپ کو دلچسپی ہوسکتی ہے Powered by Rec2Me
this is good for e-book
09 July 2019 (12:57)
what a wonderful web
04 December 2019 (05:36)
I can't log in the app!
04 September 2020 (12:57)
I loved the book can you tell me more about the ocean i wood love to talk more about the book it was the best book of all of them.
16 March 2021 (19:18)
Join the Illuminati to become rich and famous are you, business,Man or woman, politician,you need a hight rank in your office promotion, you need a charge of living. illuminati is the way. your,musician,pastor,lawyer,actor,actress,banker, and you. want to be rich, power ,get high rank, and be famous in life. You can achieve your dreams by being a member of the Great ILLUMINATI brother hood. With this all your dreams and heart desire can be fully accomplish, if you really want to be a member of the great ILLUMINATI brotherhood, every new members are entitled with sum of 10 millions dollars and a car of you choice and Golden talisman Ring, will help and protect each other if you have any problem reguilding your from or enemies, and a free visa to travel any place in the world, . Please if you are interested contact Mr Morgan Kindly us morganilluminatirich@gmail com us+14703335103
11 May 2021 (08:15)
A great library! Just can't find the Earth and Prehistoric Life Definitive Visual Guide books.
25 June 2021 (12:44)
THE DEFINITIVE VISUAL GUIDE Peter Frances, Angeles Gavira Guerrero PROJECT EDITOR Rob Houston EDITORS Rebecca Warren, Miezan van Zyl, Ruth O’Rourke, Amber Tokeley US EDITOR Christine Heilman INDEXERS Sue Butterworth, John Dear SENIOR EDITORS PROOF-READERS Polly Boyd, Ben Hoare SENIOR ART EDITOR Ina Stradins PROJECT ART EDITORS Peter Laws, Kenny Grant, Maxine Lea, Mark Lloyd Francis Wong, Matt Schofield, Steve Knowlden CARTOGRAPHERS Roger Bullen, Paul Eames, David Roberts. Iowerth Watkins DESIGNERS Julian Dams, Laragh Kedwell DTP DESIGNERS SCHERMULY DESIGN COMPANY SENIOR EDITOR Cathy Meeus Schermuly EDITORS Gill Pitts, Paul Docherty ART EDITOR Hugh Dave Ball, Lee Riches, Steve Woosnam-Savage CARTOGRAPHER Sally Geeve DESIGN ASSISTANT Tom Callingham DESIGNERS PICTURE RESEARCHER Louise Thomas ILLUSTRATORS Mick Posen (the Art Agency), John Woodcock, John Plumer, Barry Croucher (the Art Agency), Planetary Visions PRODUCTION CONTROLLER Joanna Bull MANAGING EDITORS Sarah Larter, Liz Wheeler MANAGING ART EDITOR Philip Ormerod PUBLISHING DIRECTOR Jonathan Metcalf ART DIRECTOR Bryn Walls REVISED EDITION Frances EDITOR Lili Bryant US EDITOR Jill Hamilton SENIOR ART EDITORS Anna Hall, Helen Spencer PRODUCER Mary Slater MANAGING EDITOR Angeles Gavira Guerrero MANAGING ART EDITOR Michelle Baxter PRE-PRODUCTION PRODUCER Adam Stoneham Sarah Larter ART DIRECTOR Philip Ormerod ASSOCIATE PUBLISHING DIRECTOR Liz Wheeler PUBLISHING DIRECTOR Jonathan Metcalf PUBLISHER DK INDIA SENIOR EDITOR Vineetha Mokkil PROJECT ART EDITOR Amit DTP DESIGNER Dheeraj Singh PICTURE RESEARCHER Aditya Katyal DTP MANAGER Balwant Singh MANAGING ART EDITOR Rohan Sinha Sudakshina Basu First published in the United States in 2006 This revised edition published in 2014 by DK Publishing 345 Hudson Street, New York, New York 10014 14 15 16 17 18 10 9 8 7 6 5 4 3 2 1 192969—001—Sep 2014 Copyright © 2006, 2014 Dorling Kindersley Limited Without limiting the rights under copyright reserved above, no part of this publication; may be reproduced, stored in or introduced into a retrieval system, or transmitted, in any form, or by any means (electronic, mechanical, photocopying, recording, or otherwise) without the prior written permission of the copyright ownder and the above publisher of this book. Published in Great Britain by Dorling Kindersley Limited A CIP catalog record for this book is available from the Library of Congress. ISBN 978-1-4654-1968-2 DK books are available at special discounts when purchased in bulk for sales promotions, premiums, fundraising, or educational use. For details, contact: DK Publishing Special Markets, 345 Hudson Street, New York, New York 10014 or SpecialSales@dk.com Color reproduction by Colourscan, Singapore Printed and bound in China by Leo Paper Products Discover more at www.dk.com 6 FOREWORD BY FABIEN COUSTEAU 8 INTRODUCTION OCEAN WATER THE PROPERTIES OF WATER 28 30 THE CHEMISTRY OF SEAWATER 32 TEMPERATURE AND SALINITY 34 LIGHT AND SOUND 36 OCEAN GEOLOGY 38 THE FORMATION OF EARTH 40 THE ORIGIN OF OCEANS AND CONTINENTS 42 THE EVOLUTION OF THE OCEANS 44 TECTONICS AND THE OCEAN FLOOR 48 52 OCEAN WINDS 54 SURFACE CURRENTS 58 UNDERWATER CIRCULATION 60 THE GLOBAL WATER CYCLE 64 OCEANS AND CLIMATE 66 EL NIÑO AND LA NIÑA 68 HURRICANES AND TYPHOONS 70 WAVES AND TIDES 74 OCEAN WAVES 76 TIDES 78 Malhotra EDITOR Himani Khatreja MANAGING EDITOR ABOUT THIS BOOK CIRCULATION AND CLIMATE DK UK SENIOR EDITOR Peter CONTENTS LONDON, NEW YORK, MELBOURNE, MUNICH, AND DELHI OCEAN ENVIRONMENTS COASTS AND THE SEASHORE COASTS AND SEA-LEVEL CHANGE COASTAL LANDSCAPES BEACHES AND DUNES 86 88 92 106 ESTUARIES AND LAGOONS 114 SALT MARSHES AND TIDAL FLATS 124 MANGROVE SWAMPS 130 SHALLOW SEAS 138 OCEAN LIFE INTRODUCTION TO OCEAN LIFE 204 CLASSIFICATION 206 CYCLES OF LIFE AND ENERGY BRYOZOANS 305 ECHINODERMS 306 SMALL, BOTTOM-LIVING PHYLA 313 PLANKTONIC PHYLA 317 212 TUNICATES AND LANCELETS 318 SWIMMING AND DRIFTING 214 JAWLESS FISHES 320 CONTINENTAL SHELVES 140 ROCKY SEABEDS 142 SANDY SEABEDS 144 BOTTOM LIVING 216 SHARKS, RAYS, AND CHIMAERAS 322 SEAGRASS BEDS AND KELP FORESTS ZONES OF OCEAN LIFE 218 BONY FISHES 336 146 OCEAN MIGRATIONS 220 REPTILES 368 CORAL REEFS 152 LIVING DOWN DEEP 222 BIRDS 378 164 BIOLUMINESCENCE 224 MAMMALS 400 THE HISTORY OF OCEAN LIFE 226 THE PELAGIC ZONE THE OPEN OCEAN AND OCEAN FLOOR 166 KINGDOMS OF OCEAN LIFE 230 ZONES OF THE OPEN OCEAN 168 BACTERIA AND ARCHAEA 232 SEAMOUNTS AND GUYOTS 174 CHROMISTS 234 THE CONTINENTAL SLOPE AND RISE 176 OCEAN-FLOOR SEDIMENTS 180 ABYSSAL PLAINS, TRENCHES, AND MID-OCEAN RIDGES 182 VENTS AND SEEPS 188 THE POLAR OCEANS 190 ICE SHELVES 192 ICEBERGS 194 SEA ICE 198 POLAR OCEAN CIRCULATION 200 ATLAS OF THE OCEANS BROWN SEAWEEDS 238 OCEANS OF THE WORLD PLANT LIFE 242 THE ARCTIC OCEAN 424 RED SEAWEEDS 244 THE ATLANTIC OCEAN 428 GREEN SEAWEEDS 246 THE INDIAN OCEAN 446 GREEN ALGAE 248 THE PACIFIC OCEAN 456 MOSSES 249 THE SOUTHERN OCEAN 482 FLOWERING PLANTS 250 422 FUNGI 254 GLOSSARY 488 ANIMAL LIFE 256 INDEX 494 SPONGES 258 ACKNOWLEDGMENTS 510 CNIDARIANS 260 FLATWORMS 271 RIBBON WORMS 273 SEGMENTED WORMS 274 MOLLUSKS 276 ARTHROPODS 290 6 About this Book Ocean Environments THIS BOOK IS DIVIDED INTO four chapters. An overview of the physical and chemical features of the oceans is given in the introduction; ocean environments looks at the main zones of the oceans, and ocean life examines the life-forms that inhabit them. The atlas of the oceans contains detailed maps of the oceans. Most chapters are divided into smaller sections. This chapter looks at specific parts of the oceans. It is divided into sections on different zones, starting with coasts and the seashore and then moving to progressively deeper waters, first with shallow seas and then the open ocean and ocean floor. A final section, polar oceans, looks at the frozen waters around the North and South Poles. In each section, explanatory pages describe typical features and formative processes, while the succeeding pages contain profiles of actual features. The profiles are arranged by geographical location, starting with the Arctic Ocean and followed, in order, by the Atlantic, Pacific, Indian, and Southern Oceans. SHALLOW SEAS 160 PACIFIC OCEAN WEST Shiraho Reef TYPE Fringing reef 10 square km (4 square miles) AREA Reasonable; damaged in parts by bleaching in 1998, 2007 CONDITION Southeast coast of Ishigaki Island, at the CORAL REEFSLOCATION 153 SHALLOW SEAS 152 southwestern extremity of Japanese archipelago CORAL DIVERSITY Coral Reefs Introduction Reef Formation In this seascape off a Fijian island, groups of shoaling sea goldies hover over diverse species of coral, sponges, and other reef organisms. The individual animals that make up corals are called polyps. The polyps of the main group of reef-building corals, stony corals, secrete limestone, building on the substrate underneath. The polyps also form colonies that create community skeletons in a variety of shapes. An important contributor to the life of these corals is the presence within the polyps of tiny organisms called zooxanthellae, which provide much of the polyps’ nutritional needs. Other organisms that add their skeletal remains to the reef include mollusks and echinoderms. Grazing and boring organisms also contribute, by breaking coral skeletons into sand, which fills gaps in the developing reef. Algae and other encrusting organisms help bind the sand and coral fragments together. Most reefs do not grow continuously but experience spurts of growth interspersed with quieter periods, which are sometimes associated with recovery from storm damage. CORAL REEFS ARE SOLID STRUCTURES built from the remains of small marine organisms, principally a group of colony-forming animals called stony (or hard) corals. Reefs cover about 108,000 square miles (280,000 square km) of the world’s shallow marine areas, growing gradually as the organisms that form their living surfaces multiply, spread, and die, adding their limestone skeletons to the reef. Coral reefs are among the most complex and beautiful of Earth’s ecosystems, and are home to a fantastic variety of animals and other organisms; but they are also among the most heavily utilized and economically valuable. Today, the world’s reefs are under pressure from numerous threats to their health. This opening chapter is divided into four sections. In ocean water, the properties of water itself are examined. ocean geology covers the materials of the ocean floor and the way that it changes over time. circulation and climate is about the interaction between oceans and the atmosphere and the large-scale movement of water, while tides and waves looks at movements and disturbances of water on a smaller scale. Shiraho Reef, off Ishigaki Island, part of the Japanese archipelago, came to notice in the 1980s as an outstanding example of biodiversity, with some 120 species of coral and 300 fish coral grows on shoreline, forming fringing reef BARRIER REEF Stony corals can grow only in clear, sunlit, shallow water where the temperature is at least 64˚F (18˚C), and preferably 77–84˚F (25–29˚C). They grow best where the average salinity of the water is 36 ppt (parts per thousand) and there is little wave action or sedimentation from river runoff. These conditions occur only in some tropical and subtropical areas.The highest concentration of coral reefs is found in the Indo-Pacific region, which stretches from the Red Sea to the central Pacific. A smaller concentration of reefs occurs around the Caribbean Sea. In addition to warm-water reefs, awareness is growing about other corals that do not depend on sunlight, and form deep, cold-water reefs—some of them outside the tropics (see p.178). PACIFIC OCEAN WEST Nusa Tenggara TYPE Fringing reefs, barrier reefs BARRIER REEF FRINGING REEF 5,000 square km (2,000 square miles) Nusa Tenggara is a chain of around 500 coral-fringed islands in southern Indonesia. The northern islands are volcanic in origin, while the southern islands consist mainly of uplifted coral limestone. Many of the reefs have been only rarely explored. However, what surveys have been carried out Damaged by ﬁshing practices CONDITION Southern Indonesia, from Lombok in the west to Timor in the east LOCATION COLD-WATER CORAL This species, Lophelia pertusa, is one of a few of the reef-forming corals that grow in cold water, at depths to 1,650 ft (500 m). spread of volcanic ash and gases into rain clouds THE OCEANS CONTAIN MILLIONS OF DISSOLVED chemical substances. Most of these are present in exceedingly small concentrations. Those present in significant concentrations include sea salt, which is not a single substance but a mixture of charged particles called ions. Other constituents include gases such as oxygen and carbon dioxide. One reason the oceans contain so many dissolved substances is that water is an excellent solvent. The Salty Sea salts are leached from rocks into rivers and streams and ﬂow to ocean The salt in the oceans exists in the form of charged particles, called ions, some positively charged and some negatively charged. The most common of these are sodium and chloride ions, the components of ordinary table salt (sodium chloride). Together they make up about 85 percent by mass of all the salt in the sea. Nearly all the rest is made up of the next four most common ions, which are sulfate, magnesium, calcium, and potassium. All these ions, together with several others present in smaller quantities, exist throughout the oceans in fixed proportions. Each is distributed extremely uniformly—this is in contrast to some other dissolved substances in seawater, which are unevenly distributed. Shown here are various sources, sinks, and exchange processes for the ions, salts, and minerals (yellow arrows), gases (pink arrows), and plant nutrients (turquoise arrows) in seawater. volcanic ash drifts down to sea Gases in Seawater KEY gases This section covers the properties of the water molecule, the chemistry of seawater, and the way that attributes such as temperature, pressure, and light transmission change with depth in ocean water. The main gases dissolved in seawater are nitrogen (N), oxygen (O2 ), and carbon dioxide (CO2). The levels of O2 and CO2 vary in response to the activities of photosynthesizing organisms (phytoplankton) and animals. The level of O2 is generally highest near the surface, where the gas is absorbed from the air and also produced by photosynthesizers. Its concentration drops to a minimum in a zone between about 660 ft (200 m) and 3,300 ft (1,000 m), where oxygen is consumed by bacterial oxidation of dead organic matter and by animals feeding on this matter. Deeper down, the O2 level increases again. CO2 levels are highest at depth and lowest at the surface, where the gas is taken up by photosynthesizers faster than it is produced by respiration. ions, salts, and minerals plant nutrients salt spray onto land CARBON SINK nutrients from soil wash into rivers and streams, and ﬂow to ocean washing of ions from volcanic dust and gases into sea, dissolved in rain Many marine animals, such as nautiluses (below), use carbonate (a compound of carbon and oxygen) in seawater to make their shells. After they die, the shells may form sediments and eventually rocks. dust blown off land exchange of gases between ocean and atmosphere exchange of gases between animals and seawater OXYGEN PRODUCER AND CONSUMER Oxygen levels in the upper ocean depend on the balance between its production by photo-synthesizing organisms, such as kelp, and its consumption by animals, such as ﬁsh. BREAKDOWN OF SALT If 2½ gallons (10 liters) of seawater are evaporated, about 123/4 oz (354 g) of salts are obtained, of the types shown below. 2½ gallons (10 liters) of seawater Nutrients other salts 1/4 oz (7.5g) calcium sulfate (gypsum) 2/3oz (17.7g) magnesium salts 2oz (54.8g) sodium chloride (halite) 10oz (274g) + – – – Na+ – – – – + – + + + + + + Cl– + + + – + + – – chloride ion (negative charge) uptake of nutrients by phytoplankton nutrient upwelling exchange of gases between phytoplankton and seawater – – – water molecule – PEOPLE ALEXANDER MARCET The Swiss chemist and doctor Alexander Marcet (1770–1822) carried out some of the earliest research in marine chemistry. He is best known for his discovery, in 1819, that all the main chemical ions in seawater (such as sodium, chloride, and magnesium ions) are present in exactly the same proportions throughout the world’s oceans. The unchanging ratio between the ions holds true regardless of any variations in the salinity of water and is known today as the principle of constant proportions. Sources and Sinks sinking and release of minerals from hydrothermal vents decomposition The ions that make up the salt in the oceans have arrived of dead there through various processes. Some were dissolved out of organisms rocks on land by the action of rainwater and carried to the sea in rivers. Others entered the sea in the emanations of hydrothermal vents (see p.188), in dust blown off the land, or came from volcanic ash. There are also “sinks” for every type of ion—processes that remove them from seawater. These range from salt spray onto land to the precipitation of various ions onto the seafloor as mineral deposits. Each type of ion has a characteristic residence time. This is the time that an ion remains in seawater before it is removed. The common ions in seawater have long residence times, ranging from a few hundred years to hundreds of millions of years. The Origin of Oceans and Continents OCEAN GEOLOGY ▶ polar easterly Ocean Winds polar-front jet stream—narrow ribbon of strong wind at high altitude at top of front THE PATTERN OF AIR MOVEMENT over the oceans results from solar heating of the atmosphere and Earth’s rotation. This pattern of winds is modified by linked areas of low and high pressure (cyclones and anticyclones), which continually move over the oceans’ surface. Near coasts, additional onshore and offshore breezes are common. These are caused by differences in the capacity of sea and land to absorb heat. The atmospheric cells cause north–south air movements. These are altered by the Coriolis effect. As the Earth spins, parcels of air at different latitudes in the atmosphere have different west-to-east velocities (air at the Equator moves fastest). When they change latitude by moving to the north or south, they retain these west-to-east velocities, which differ from those of air in the AIR DEFLECTIONS In the Northern Hemisphere, latitudes they move into. Hence, the air veers to the Coriolis effect causes all air movements to be the east (in the direction deﬂected to the right of of Earth’s spin) when their initial direction. In moving away from the the Southern Hemisphere, Equator and to the west they veer to the left. when moving toward it. air deﬂected to right air deﬂected to left initial direction of air movement westerlies polar northeasterlies westerlies northeasterly monsoon (Nov–Mar) northeasterly trade winds Tropic of Cancer equator Tropic of Capricorn top layer of upper mantle bombardment gradually erased THE EARLY EARTH mantle vigorous convection cells in upper mantle The oceanic crust has a higher density than the continental crust, making it less buoyant. Both types of crust can be thought of as floating on the “plastic” upper mantle, and the oceanic crust lies lower due to its lower buoyancy. It is relatively thin, with a depth of never more than 7 miles (11 km), compared with a thickness of 15–43 miles (25–70 km) for most continental crust. It consists mainly of basalt, an igneous rock that is low in silica compared with continental rocks, and richer in calcium than the mantle. Basalt lava is created when hot material in the upper mantle is decompressed, allowing it to melt and form liquid magma. The decompression occurs beneath rifts in the crust, such as those found at the mid-ocean ridges, and it is through these rifts that lava is extruded onto the surface to create new ocean crust. westerlies volcanic eruptions add gases and water vapor to atmosphere MANTLE ROCKS ANDEAN VOLCANOES This radar image shows volcanoes formed from andesite lava, whose composition is intermediate between oceanic and continental rocks. 55 This section describes the large-scale circulation of the oceans, both deep down and at the surface. It also looks at ocean climates and the many ways that the oceans and the atmosphere inﬂuence one another. northeasterly trade wind SATELLITE IMAGING air ascends from cyclone air descends into anticyclone low pressure at center central area of high pressure cold air sinks Prevailing Winds The winds produced by pressure differences and modified by the Coriolis effect are called the prevailing winds. In the tropics and subtropics, the air movements toward the equator in Hadley cells are deflected to the west. These are known as trade winds. They comprise the northeasterly trades in the Northern Hemisphere, and southeasterly trades in the south. At higher latitudes, the surface winds in Ferrel cells deflect to the east, producing the westerlies. In the Southern Hemisphere, these winds blow from west to east without meeting land. Those around latitudes of 40˚S are known as the Roaring Forties. In polar regions, winds deflect to the west as they move away from the poles. These are known as polar northeasterlies and southeasterlies. southwesterly monsoon (Apr–Oct) Pressure-system Winds warm air rising ASCAT antenna (one of three) prevailing cool local warm local cool air spirals around central area of low pressure air moving from high to low pressure deﬂected by Coriolis effect to form spiral cold air ﬂows toward area of low pressure In any area of ocean where air sinks—often at subtropical latitudes—a zone of high atmospheric pressure, or anticyclone, develops. Where warm air rises, areas of low pressure, called cyclones or depressions, occur. These often develop near the equator and subpolar latitudes. Cyclones and anticyclones create linked, circulating wind patterns, which continually move and change. In the Northern Hemisphere, there is a clockwise movement of air around an anticyclone, and a counterclockwise motion CYCLONES AND ANTICYCLONES around a cyclone. This pattern is reversed in the Air moves from an area of Southern Hemisphere. Local pressure systems can affect high pressure toward one the general pattern of prevailing winds. In particular, of low pressure, but the cyclones move swiftly over the ocean and can produce Coriolis effect modiﬁes this, producing circular winds. rapid changes in wind strength and direction. warm air cools at high altitude BREEZY COAST 77 Ocean Waves Wave Generation WAVES ARE DISTURBANCES in the ocean that transmit energy from one place to another. The most familiar types of waves—the ones that cause boats to bob up and down on the open sea and dissipate as breakers on beaches—are generated by wind on the ocean surface. Other wave types include tsunamis, which are often caused by underwater earthquakes (see p.49), and internal waves, which travel underwater between water masses. Tides (see p.78) are also a type of wave. Wave Properties direction of wave motion TIDES AND WAVES ▶ trough Wind energy is imparted to the sea surface through friction and pressure, causing waves. As the wind gains strength, the surface develops gradually from flat and smooth through growing levels of roughness. First, ripples form, then larger waves, called chop. The waves continue to build, their maximum size depending on three factors: wind speed, wind duration, and the area over which the wind is blowing, called the fetch. When waves are as large as they can get under the current conditions of wind speed and size of fetch, the sea surface is said to be “fully developed.” The overall state of a sea surface can be summarized by the significant wave height—defined as the average height of the highest one-third of the waves. For example, in a fully developed sea produced by winds of about 25 mph (40 kph), the significant wave height is typically about 8 ft (2.5 m). wave height (amplitude) disordered sea surface in fetch area wind direction ripples turn to chop PHYLUM Mollusca CLASSES 8 SPECIES 73,683 Anatomy Most mollusks have a head, a soft body mass, and a muscular foot. The foot is formed from the lower body surface and helps it to move. Mollusks have what is called a hydrostatic skeleton—their bodies are supported by internal fluid pressure rather than a hard skeleton. All mollusks have a mantle, a body layer that covers the upper body and may or may not secrete a shell. The shell of bivalves (clams and relatives) has two halves joined by a hinge; these can be held closed by powerful muscles while the tide is out, or if danger threatens. Mollusks other than bivalves have a rasping mouthpart, or radula, which is unique to mollusks. Cephalopods (octopuses, squid, and cuttlefish) also have beaklike jaws as well as tentacles, but most lack a shell, while most gastropods (slugs and snails) have a single shell. This is usually a spiral in snails, but can be cone-shaped in other forms, such as limpets. color-coded panel shows position of group being described (indicated with white outline) in the classiﬁcation hierarchy gill outside the fetch, waves become sorted by speed and wavelength wave shortens in length and decreases in speed but increases in height muscular foot wave ﬁnally breaks radula hinge ligament BIVALVE ANATOMY Bivalves are housed within a shell of two halves (right) from which the siphons and muscular foot can be extended. The shell is opened and closed by the adductor muscles, labeled in the body plan (far right). CHOPPY SEA In a choppy sea, the waves are 4–20 in (10–50 cm) high and have a wavelength of 10–40 ft (3–12 m). direction of wave advance fetch (area over which wind blows) wave reaches critical ratio of height to length and begins to break water motion caused by the wave begins to interact with the sea bed and slow down FULLY DEVELOPED ROUGH SEA Wind speeds over 40 mph (60 kph) can generate very rough seas with waves more than 10 ft (3 m) high. path of individual water particle PARTICLE MOVEMENT Wave Propagation Interference between two or more large waves occasionally causes a giant or “rogue” wave. This one, recorded in the Atlantic Ocean in 1986, had an estimated height of 56 ft (17 m). It broke over the ship pictured, bending its foremast back by 20˚. eye SPIRAL SNAIL SHELL water motion occurs offshore to depth of half the wavelength GROUP INTRODUCTION ▶ BUILDING WAVES ROGUE WAVES mantle cavity digestive system These tiny waves are just a few millimetres high and have a wavelength of under 1½ in (4 cm). SWELL A swell is a series of large, evenly spaced waves, often observed hundreds of miles away from the storm that spawned them. Wavelengths range from tens to hundreds of feet. SHOALING AND BREAKING Shoaling occurs as waves enter shallow water. The wave length and speed both decrease, but the wave gains height. When the crest gets too steep, it curls and breaks. HUMAN IMPACT RIDING THE WAVES When a swell reaches a suitably shaped beach, it can produce excellent surfing conditions. Small spilling breakers are ideal for novice surfers, while experts seek out large plunging breakers that form a “tube” they can ride along. For tube-riding, the break of the wave must progress smoothly either to the right or left. Here, a surfer rides a rightbreaking wave in Hawaii— it is breaking from left to right behind the surfer. Arrival on Shore As waves approach a shore, the motion they generate at depth begins to interact with the sea floor. This slows the waves down and causes the crests in a series of waves to bunch up—an effect called shoaling. The period of the waves does not change, but they gain height as the energy each contains is compressed into a shorter horizontal distance, and eventually break. There are two main types of breaker. Spilling breakers occur on flatter shores: their crests break and cascade down the front as they draw near the shore, dissipating energy gradually. In a plunging breaker, which occurs on steeper shores, the crest curls and falls over the front of the advancing wave, and the whole wave then collapses at once. Waves can also refract as they reach a coastline. This concentrates wave energy onto headlands (see p.93) and shapes some types of beach (see p.106). WAVE REFRACTION When waves enter a bay enclosed by headlands, they are refracted (bent) as different parts of the wave-front encounter shallow water and slow down. INTRODUCTION In the fetch, many different groups of waves of varying wavelength are generated and interfere. As they disperse away from the fetch, the waves become more regularly sized and spaced. This is because the speed of a wave in open water is closely related to its wavelength. The different groups of waves move at different speeds and so are naturally sorted by wavelength: the largest, fastest-moving waves at the fore, the smaller, slower-moving ones behind. This produces a regular wave pattern, or swell. Occasionally, groups of waves from separate storms interfere to produce unusually large “rogue” waves. As they propagate across the open ocean, wind-generated waves maintain a constant speed, which is unaffected by depth until they reach shallow water. Only with waves of extremely long wavelength—tsunamis—is the speed of propagation affected by water depth. water carried up shore in swash zone Pages such as the ones shown here describe groups of organisms in general. All introductions contain an account of the deﬁning physical characteristics, usually followed by further information on behavior, habitats, and classiﬁcation. REEF-DWELLING GOLIATH The tropical giant clam is the largest bivalve and may measure more than 3 ft (1 m) across and weigh over 440 lb (220 kg). GASTROPOD ANATOMY spiral shell sensory tentacle direction of wave motion Within the wave-generation area, the sea surface is usually quite confused—the result of groups of waves of different size and wavelength interfering with each other. Outside this area, the waves become sorted by speed to produce a more regular pattern, called a swell. crest As waves pass over the surface, the particles of water do not move forward with the waves. Instead, they gyrate in little circles or loops. Underwater, the particles move in ever-smaller loops. At a depth below about half the distance between crests, they are quite still. AMONG THE MOST SUCCESSFUL of all marine animals, mollusks display great diversity and a remarkable range of body forms, allowing them to live almost everywhere from the ocean depths to the splash zone. They include oysters, sea slugs, and octopuses. Most species have shells SPECIES 73,683 and are passive or slow-moving; some lack eyes. Others are intelligent, active hunters with complex nervous systems and large eyes. Filter-feeding mollusks, such as clams, are crucial to coastal ecosystems, as they provide food for other animals and improve water quality and clarity. Many mollusks are commercially important for food, pearls, and their shells. DOMAIN Eucarya KINGDOM Animalia CAPILLARY WAVES (RIPPLES) A group of waves consists of several crests separated by troughs. The height of the waves is called the amplitude, the distance between successive wave crests is known as the wavelength, and the time between successive wave crests is the period. Waves are classified into types based on their periods. They range from ripples, which have periods of less than 0.5 seconds, up to tsunamis and tides, whose periods are measured in minutes and hours (their wavelengths range from hundreds to thousands of miles). In between these extremes are chop and swell—the most familiar types of surface wave. Ocean waves behave like light rays: they are reflected or refracted by obstacles they encounter, such as islands. When different wave groups meet, they interfere—adding to, or canceling, each other. wavelength PLUNGING BREAKER “Barrel” or “tube-forming” breakers like this occur when the waves reaching shore have large amounts of energy. The seabed must be ﬁrm and quite steep. ANIMAL LIFE Mollusks PHYLUM Mollusca CLASSES 8 DAY AND NIGHT WAVES AND TIDES still-water level 276 Land heats up faster Local winds, called onshore and offshore than water during the day. air heats up Warm air rises over the land and rises over cool air breezes, are generated near coasts, especially in land drawn in and draws in cold air from sunny climes. Onshore breezes—sometimes the sea. At night, the land called sea breezes—develop during the day. cools more quickly, These are caused by the land heating up more reversing the airﬂow. quickly than the sea, as both absorb solar radiation. This occurs because the sea absorbs ONSHORE BREEZE large quantities of heat energy with only a small rise in temperature, whereas the same amount of heat energy is cold air sinks air heats up likely to cause the land temperature to rise sharply (see p.31). cool air drawn and rises As the land warms up, it heats the air above it, causing the air to rise. over ocean seaward Cooler air then blows in from the sea to take its place. In the evening, and at night, the opposite effect occurs. At nightfall, the land quickly cools down, but the sea remains warm and continues to heat the air above it. As this warm air rises, it sucks the cooler air off the land, and so generates an offshore breeze. This is sometimes called a “land breeze.” OFFSHORE BREEZE On warm coasts, there is often a noticeable drop in temperature from midday as a cool sea breeze blows in off the water. The breeze typically reverses in the evening and at night. 76 The regular movements of the tides are described here, as well as the way that disturbances spread out across the surface in the form of waves. cold air sinks Coastal Breezes PATTERN OF WINDS Year-round, the winds over most oceans are trades or westerlies. An exception is the northern Indian Ocean—this has a monsoon climate, in which a seasonal switch in wind direction occurs. This chapter contains two sections. The introduction to ocean life covers the ecology and history of marine life and the way that marine organisms are classified. It is followed by a larger section, kingdoms of ocean life. This is divided into domains or kingdoms and, in the case of the plant and animal kingdoms, further divided into smaller groups. In each case, a general overview of the organisms that make up the group is followed by profiles of a selection of individual species. The section begins with the smallest forms of life, the bacteria and archaea, and ends with the animal kingdom. KINGDOM Animalia ◀ CIRCULATION AND CLIMATE southeasterly trade wind Ocean winds are monitored by instruments called scatterometers, such as an instrument called ASCAT on the METOP-A satellite (right). A scatterometer is a radar device that can measure both wind speed and direction. REEF FLAT OFF PANTAR ISLAND This shallow reef area, featuring numerous species of stony coral and a starﬁsh, is in east Nusa Tenggara. DOMAIN Eucarya LONG-HAUL SAILING trade winds meet at Intertropical Convergence Zone prevailing warm southeasterly trade winds rifts occur when fragments of crust move apart solid inner core air rises at equator air descends at pole coral continues to grow where waves bring food Winds can blow with a consistent strength and direction over large areas of ocean. Consequently, on long-haul sailing trips, the same basic sail settings can often be used for days on end. air descends in subtropical latitudes southeasterly trade winds southeasterlies Earth had deep oceans from an early stage, with volcanoes and an increasing area of continental crust standing above the surface. The ocean became salty as weathering of surface rocks added minerals to the water. liquid outer core volcanic activity adds igneous rocks to surface above rising ﬂows Peridotite is the dominant rock type found in the mantle, consisting of silicates of magnesium, iron, and other metals. Sometimes it is brought to the surface when parts of the ocean ﬂoor are uplifted, as here in Newfoundland, Canada, or as fragments from volcanic activity. KEY southeasterly trade winds rivers erode and transport sediment INTRODUCTION INTRODUCTION Intertropical Convergence Zone westerlies sedimentary rocks During the process of differentiation, volatile materials were expelled from Earth’s interior by volcanic activity. The lightest gases, such as hydrogen and helium, would quickly have been lost to space, leaving a stable atmosphere of nitrogen, carbon dioxide, and water vapor. Some of the water vapor would have condensed to form liquid water, and it seems there was a significant ocean earlier than 4 billion years ago. Some meteorites contain 15-20 percent ocean water from water and the early Earth is thought volcanic eruptions and comet to have had the same composition, impacts providing an ample source for the early ocean. More water arrived with impacting comets. It was in the ocean that free oxygen first appeared, with the arrival traces of early of photo- synthesizing life around 3.5 billion years ago. meteorite and comet primitive oceanic crust DISCOVERY The Coriolis Effect crust pulled apart by convective motion in mantle 43 BANDED IRON Known as a banded-iron formation, this layered rock contains iron oxides that formed as the oxygen content of early oceans increased. Hadley cell Solar heating causes the air in Earth’s atmosphere to CIRCULATION CELLS The atmospheric cells cycle around the globe in three sets of giant loops, produce north–south called atmospheric cells. Hadley cells are produced by airﬂows. These are modiﬁed by Earth’s warm air rising near the equator, cooling in the upper spin, producing winds atmosphere, and descending to the surface around that blow diagonally. subtropical latitudes (30˚N and S). Then the air moves subtropical back toward the equator. Ferrel cells are produced by jet stream air rising around subpolar latitudes (60˚N and S), cooling and falling in polar-front jet stream the subtropics, and then moving toward the poles. Polar cells are caused by air descending at the poles and moving toward the equator. Earth’s rotation air rises in subpolar latitudes Ferrel cell southwesterly wind primitive continental crust thickens above sinking mantle ﬂow, without mantle interference direction of Earth’s spin Atmospheric Cells initial direction of air movement polar cell Moho OCEAN-FLOOR STRUCTURE Three layers of basalt in the crust (basaltic lava, dikes, and gabbro) are separated from the mantle by the Mohorovičić discontinuity (the Moho). The top layer of the upper mantle is fused to the base of the crust to form the rigid lithosphere, which makes up tectonic plates.The asthenosphere is the soft zone over which the plates of the lithosphere glide. INTRODUCTION CIRCULATION AND CLIMATE ocean crust lithosphere magma rises to surface basalt continuously intrudes from mantle ZIRCON Water and Atmosphere Oceanic Crust ocean surface peridotite INTRODUCTION 54 basalt sheets (dikes) sediment gabbro asthenosphere central area ﬁlled by reef limestone Ocean Life greenstone belts above rising mantle ﬂow zircon crystals, among the earliest continental crust materials Continental Crust The continents include a wide range of rock THE OLDEST ROCKS types, including granitic igneous rocks, sedimentary These sedimentary rocks on Bafﬁn Island rocks, and the metamorphic rocks formed by the lie on the Canadian alteration of both. They contain a lot of quartz, a Shield. The stable mineral absent in oceanic crust. The first continental continental shields rocks were the result of repeated melting, cooling, contain the world’s most ancient rocks, and remixing of oceanic crust, driven by volcanic activity above mantle convection cells, which were which are around 4 billion years old. much more numerous and vigorous than today’s. Each cycle left more of the heavier components in the upper mantle and concentrated more of the lighter components in the crust. The first microcontinents grew as lighter fragments of crust collided and fused. Thickening of the crust led to melting at its base and underplating with granitic igneous rocks. Weathering accelerated the process of continental rock formation, retaining the most resistant components, such as quartz, while washing solubles into the ocean. rift volcanic island becomes submerged These pages describe general types of environments. The example above is taken from the SHALLOW SEAS section. THE ORIGIN OF OCEANS AND CONTINENTS DEVELOPMENT OF CONTINENTAL CRUST Modiﬁcation of the crust above rising mantle ﬂows was delayed by the continuous intrusion of mantle basalt, resulting in the greenstone belts found today at the heart of each continental shield. EARTH’S OCEANS FORMED MORE THAN 4 billion years ago, mainly from water vapor that condensed from its primitive atmosphere but also from water brought from space by comets. Initially, after acquiring a layered internal structure, the Earth had a uniform crust that was enriched in lighter elements and floated on an upper mantle made of denser materials. Later, the crust became differentiated into two types as continents began to form, made from rocks that were chemically distinct from those underlying the oceans. basaltic lava Bleaching refers to color loss in reef-building corals and occurs when the tiny organisms called zooxanthellae, which give corals their colors, are ejected from coral polyps or lose their pigment. In extreme cases, this can lead to the coral’s death.Various stresses can cause bleaching, including pollution, ocean temperature rise, and ocean acidification (see p.67). In recent decades, some mass bleaching events have affected reefs over wide areas. coral continues to grow, forming barrier reef INTRODUCTION As well as describing the composition of the ocean ﬂoor, this section looks at the processes that shape it, tracing the origin of the oceans and their changing size and shape over geological time. ATOLL This satellite image of the Skagerrak (a strait linking the North and Baltic seas) shows a bloom of phytoplankton, visible as a turquoise discoloration in the water. These tiny forms of planktonic organisms have cell walls made of silicate. They can only grow if there are sufﬁcient amounts of silica present in the water. OCEAN GEOLOGY 42 An atoll is shown here forming around a volcanic island. First, the island’s shore is colonized by corals forming a fringing reef (above). Over time, the island subsides, but coral growth continues, forming a barrier reef (above right). Finally, the island disappears, but the coral maintains growth, forming an atoll (right). Atolls can also form as a result of sea-level rise. reef face ▲ EXPLANATORY PAGES SILICEOUS DIATOMS RIVER DISCHARGE River discharge is a mechanism by which ions of sea salt and nutrients enter the oceans. Here, the Noosa River empties into the sea on the coast of Queensland, Australia. CORAL BLEACHING lagoon of shallow water ATOLL FORMATION PLANKTON BLOOM dissolving of minerals from sea ﬂoor precipitation of minerals onto sea ﬂoor carbonates incorporated into seaﬂoor sediments from animal shells INTRODUCTION INTRODUCTION slow uplift of sedimentary rocks at continental margins, exposing salts, minerals, and ions at surface – sodium chloride crystal Numerous substances present in small amounts in seawater are essential for marine organisms to grow. At the base of the oceanic food chain are phytoplankton—microscopic floating life-forms that obtain energy by photosynthesis. Phytoplankton need substances such as nitrates, iron, and phosphates in order to grow and multiply. If the supply of these nutrients dries up, their growth stops; conversely, blooms (rapid growth phases) occur if it increases. Although the sea receives some input of nutrients from sources such as rivers, the main supply comes from a continuous cycle within the ocean. As organisms die, they sink to the ocean floor, where their tissues decompose and release nutrients. Upwelling of seawater from the ocean floor (see p.60) recharges the surface waters with vital substances, where they are taken up by the phytoplankton, refueling the chain. sodium ion (positive charge) + + + WATER AS A SOLVENT The charge imbalance on its molecules makes water a good solvent. When dissolving and holding sodium chloride in solution, the positive ends of the molecules face the chloride ions and the negative ends face the sodium ions. ◀ OCEAN WATER lagoon volcanic island The body plan (far left) of gastropods (slugs and snails) features a head, large foot, and usually a spiral shell (left). In shelled forms, all the soft body parts can be withdrawn into the shell for protection, or to conserve moisture while uncovered by the outgoing tide. shell mantle cavity digestive system siphon muscular foot BIVALVE SHELL gill adductor muscle jaws feeding arm radula OCEAN LIFE The Chemistry of Seawater SOURCES, SINKS, AND EXCHANGES 33 OCEAN ENVIRONMENTS THE CHEMISTRY OF SEAWATER OCEAN ENVIRONMENTS OCEAN WATER OCEAN ENVIRONMENTS HUMAN IMPACT 32 digestive system eye arm internal shell siphon gill mantle cavity TYPE Atol 330 (130 squar AREA CONDITION recovering bleaching Central Sulu Sea, between t and northern Borneo LOCATION The Tubbataha Reefs lie arou atolls in the centre of the Sul are famous for the many larg (open ocean) marine animals to them – such as sharks, Ma turtles, and barracuda. The ste shelving reefs here are also ri smaller life, including many s of crustaceans, colourful nud (sea slugs), and more than 35 of stony and soft coral. In the early 1990s, the Tub Reefs were rated by scuba di among the top ten dive sites world. However, during the they suffered considerable da from destructive fishing pract the establishment of a seawee In this photograph of a steeply she reef slope, several species of soft are visible, together with a shoal o Longﬁn Bannerﬁsh. AREA The conditions needed for the growth of warm-water coral reefs are found mainly within tropical areas of the Indian, Paciﬁc, and Atlantic oceans. The reefs are chieﬂy in the western parts of these oceans, where the waters are warmer than in the eastern areas. An atoll is a ring of coral reefs or coral islands enclosing a central lagoon. It may be elliptical or irregular in shape. island subsides when volcano has become inactive PACIFIC OCEAN WEST Tubbataha Reefs CORAL DROP-OFF Distribution of Reefs ATOLL A barrier reef is separated from the coast by a lagoon. In this aerial view, the light blue area is the reef and the distant dark blue area is the lagoon. sea level Despite its name, the colour of this coral varies from violet through blue, turquoise, and green to yellow-brown. Its branching vertical plates can form massive colonies. This group of branching hard corals is growing at a depth of about 16 ft (5 m) off the coast of eastern Indonesia. Individual stony corals can grow up to a few inches per year. OPEN POLYPS At the center of each polyp is an opening, the mouth, which leads to an internal gut. The tissue around the gut secretes limestone, which builds the reef. WARM-WATER REEF AREAS A fringing reef directly borders the shore of an island or large landmass, with no deep lagoon. BLUE RIDGE CORAL STONY CORAL Types of Reefs Coral reefs fall into three main types: fringing reefs, barrier reefs, and atolls. The most common are fringing reefs. These occur adjacent to land, with little or no separation from the shore, and develop through upward growth of reef-forming corals on an area of continental shelf. Barrier reefs are broader and separated from land by a stretch of water, called a lagoon, that can be many miles wide and dozens of yards deep. Atolls are large, ring-shaped reefs, enclosing a central lagoon; most atolls are found well away from large landmasses, such as in the South Pacific. Parts of the reef structure in both atolls and barrier reefs often protrude above sea level as low-lying coral islands—these develop as wave action deposits coral fragments broken off from the reef itself. Two other types of reefs are patch reefs—small structures found within the lagoons of other reef types—and bank reefs, comprising various reef structures that have no obvious link to a coastline. FRINGING REEF species concentrated in a few square kilometres. The reef also contains the world’s largest colony of rare Blue Ridge Coral (Heliopora coerulea). For decades, environmentalists battled to save the reef from the building of a new airport for Ishigaki. A proposal to construct the airport on top of the reef was dropped, but concern remains now that it has been built on land, as discharge of excavated soil into the reef is likely to have an adverse effect. CEPHALOPOD ANATOMY Cephalopods have large eyes, in front of which there are a number of tentacles. The siphon functions in respiration and in rapid movement. Some forms have a ﬂattened internal shell. indicate an extremely high d marine life in this region. Fo a single large reef can contai than 1,200 species of fish (m in all the seas in Europe com and 500 different species of building coral. Common ani include Eagle Rays, Manta R 7 Atlas of the Oceans PACIFIC OCEAN SOUTHWEST Great Barrier Reef TYPE map shows location and, in most proﬁles, geographical extent of feature Barrier reef table of summary information (categories vary between sections) 14,300 square miles (37,000 square km) AREA CONDITION Damaged by Crown-of-thorns Starﬁsh; coral bleaching Parallel to Queensland coast, northeastern Australia LOCATION Parallel to Queensland coast, northeastern Australia LOCATION A HABITAT Middle and lower rocky shores Caribbean, Bahamas, Florida DISTRIBUTION Northwestern and northeastern Atlantic OCEAN LIFE One of the most common rocky shore gastropods, the dog whelk has a thick, heavy, sharply pointed spiral shell. The shell’s exact shape depends on its exposure to wave action, and its color depends on diet. Dog whelks are voracious predators, feeding mainly on barnacles and mussels. Once the prey has been located, the whelk uses its radula to bore a hole in the shell of its prey before sucking out the flesh. Sense Organs PIGMENTED SKIN CELLS HELP CUTTLEFISH TO CHANGE COLOR When the cuttleﬁsh passes over a darker background, it disperses the colored pigments throughout each of its chromatophores, and the animal darkens. 2 MOLLUSCAN BEAUTY Displaying fabulous warning colors, this nudibranch is a shell-less example of the many thousands of marine species of gastropods (slugs and snails). K il ur re eT nc 33m (108ft) B 1,857m (6,093ft) Bowers Attu Attu Near Basin Island Islands Agattu Island e u DISTRIBUTION HIDING FROM VIEW There are times when the Venus comb buries itself just below the surface of the sea floor, displacing the sand with movements of its muscular foot. However, it leaves the opening of its tubular inhalant siphon above the sand’s surface so that it can draw water into its mantle cavity to obtain oxygen and to “taste” the water for the presence of prey. CLASS GASTROPODA Giant Triton Charonia tritonis LENGTH Up to 16 in (40 cm) HABITAT Coral reefs, mostly in subtidal zones DISTRIBUTION Indian Ocean, western and central Paciﬁc CLASS GASTROPODA HALF BURIED The spines of this Venus comb can be seen sticking out of the sand. The siphon is visible to the right of the picture. Common Periwinkle Littorina littorea CLASS GASTROPODA Flamingo Tongue LENGTH 1–11/2 in (3–4 cm) HABITAT Western Atlantic, from North Carolina to Brazil; Gulf of Mexico, Caribbean Sea 277 The off-white shell of the flamingo tongue cowrie is usually almost completely hidden by the two fleshy, leopard-spotted extensions of its body’s outer casing, or mantle. When threatened, however, its distinctive coloration quickly disappears as it withdraws all its soft body parts into its shell for protection. This snail feeds almost exclusively on gorgonian corals, which dominate Caribbean reef communities. Although these corals release chemical defenses to repulse predators, the flamingo tongue cowrie is apparently able to degrade these bioactive compounds and eat the corals without coming to any harm. After mating, the female strips part of a soft coral branch and deposits the egg capsules on it. Each capsule contains a single egg that will hatch into a free-swimming planktonic larva. LENGTH Up to 1 in (3 cm) HABITAT Upper shore to sublittoral rocky shores, mud ﬂats, estuaries Coastal waters of northwest Europe; introduced to North America DISTRIBUTION This gastropod is one of the very few animals that eats the crown-of-thorns starfish, itself a voracious predator and destroyer of coral reefs. The giant triton is an active hunter that will chase prey, such as starfish, mollusks, and sea stars, once it has detected them. It uses its muscular single foot to hold its victim down while it cuts through any protective covering using its serrated, tonguelike radula; it then releases paralyzing saliva into the body before eating the subdued prey. directly into the water during the spring tides. The eggs hatch into free-swimming larvae that float in the plankton for up to six weeks. After settling and metamorphosing into the adult form, it takes a further two to three years for the adult to fully mature. It feeds mainly on algae, which it rasps from the rocks. In the 19th century, the common periwinkle was accidentally introduced into North America, where its selective grazing of fast-growing algal species has considerably affected the ecology of some rocky shores. The common periwinkle has a black to dark gray, sharply conical shell and slightly flattened tentacles, which in juveniles also have conspicuous black banding. The sexes are separate and fertilization occurs internally. Females release egg capsules, containing two or three eggs, ◀ SPECIES PROFILES GRAFTING OYSTERS All species proﬁles contain a text description and, in most cases, a color photograph and distribution map. Pearls form in oysters when a grain of sand or other irritant lodges in their shells. The oyster coats the grain with a substance called nacre, forming a pearl. Today many pearls are cultured artificially: the shell is opened just enough to introduce an irritant into the mantle cavity. CLASS GASTROPODA Flamingo Tongue Movement Mollusks move in many different ways. Most gastropods glide across surfaces using their mucus-lubricated foot. Exceptions include the sea butterfly, which has a modified foot with finlike extensions for swimming. Some bivalves, such as scallops, also swim, producing jerky movements by clapping the two halves of their shell together. Other bivalves burrow by probing with their foot and then pulling themselves downward by muscular action. Cephalopods are efficient swimmers; some have fins on the sides of their bodies that let them hover in the water, and they can accelerate rapidly by squirting water out through their siphons. Cyphoma gibbosum LENGTH 1–11/2 in (3–4 cm) name of group to which species belongs common name of species is followed by scientiﬁc name HABITAT Coral reefs at about 50 ft (15 m) AIDED BY MUCUS Muscular contractions ripple through the ﬂeshy foot of this marine snail. It secretes a lubricating mucus that helps it to move on rough surfaces. Respiration Most mollusks obtain oxygen from water using gills, called ctenidia, which are situated in the mantle cavity. These are delicate structures with an extensive capillary network and a large surface area for gaseous exchange. In species that are always submerged, water can continually be drawn in and over the gills. Those living in the intertidal zone are exposed to the air for short periods and must keep their gills moist. At low tide, bivalves clamp shut and some gastropods close their shell with a “door” (called an operculum) to retain moisture. Pulmonate snails have a simple lung formed from the mantle cavity instead of ctenidia and are mostly terrestrial but others live on the seashore and can absorb oxygen through their skin when immersed.The respiratory pigment in most molluscan blood is a copper compound called hemocyanin. It is not as efficient at taking up oxygen as external gills hemoglobin and gives mollusks’ (ctenidia) blood a blue color. Nudibranchs (sea slugs) have feathery external gills toward the rear of their bodies. The warning coloration of this species includes the bright orange gills. DISTRIBUTION Western Atlantic, from North Carolina to Brazil; Gulf of Mexico, Caribbean Sea OCEAN LIFE COLOR CODING en Riv er Yuk on Riv kw im ko Ra t I sla nd s Kiska Island Amchitka Island ch 20m (66ft) Inlet K Cook rai t a Pe ni ns f ko St Tanaga A Island ds leutian Islan Atka Island Atka n Ale Isla Fox E Po r B a tl oc nk k Kodiak Kodiak Island i Tr en ch Gulf of Alaska Patton Seamount Patt on Seamou nts Murray Seamount Gilbert Seamount G i lb er Parker Seamount 5,267m (17,281ft) 160˚W F ut an G 2 sea depth maximum depth on map Chichagof Admiralty Island Island 295m A Sitka (968ft) 3,640m Baranof (11,943ft) Island Ketchikan of Alask a Seamount Pr ovinc Prince of e Gulf Pratt Wales Quinn Seamount Prince Rupert Island n Giacomini Seamount Durgin o ce Seamount Dixtran Seamount K Cape En o Surveyor Seamdiak Knox Seamount ount Dickins s Welker Seamount Shumagin Islands so Dutch Davidnk Umnak Harbor Ba Island Unalaska nds Island Juneau Glacier Bay Port Moller Unimak Island False Pass 7,314m 170˚W (23,997ft) D Bristol Bay 62m (203ft) ul Cape Constantine Umnak Be Plateau ring Cany on Andreano f Islands 180˚ C Cape Newenham Pribilof Islands 6,102m (20,021ft) Shuyak Island li Bering Sea 11m (36ft) Bowers Bank Homer seamount Yakutat Prince Cape William Saint Elias Sound tectonic plate boundary Gibson Seamount 150˚W H Seamount Denson Seamount Alaska Plain White Marsh Seamount t Se a mo Schoppe un I Ridge Peters ts 766m (2,513ft) e en Ch a rlo t Bowie te Seamount Oshawa Seamount Miller Seamount Ridge 140˚W Isla n 3 213m t (699ft) Cape St.James QueenCharlotte Sound Cape Scott ds Explorer Seamount 130˚W J K 50˚N rait of Vancouve r Vancouver G Island eorgia Victoria Strait of Seattle Juan de Fuca 4 UNITED STATES OF AMERICA Cascadia Basin L John Sparks is a curator in the Department of Ichthyology at the American Museum of Natural History and an adjunct professor at Columbia University in New York City. The revised edition was prepared with the help of Mark Siddall, a curator in the Division of Invertebrate Zoology and a professor at the Richard Gilder Graduate School at the American Museum of Natural History. Indian Ocean, western Paciﬁc One of the largest cowrie species, the tiger cowrie has a shiny, smooth, domed shell with a long, narrow aperture, and is variously mottled in black, brown, cream, and orange. The cowrie’s mantle (its body’s outer, enclosing layer) can extend to cover parts of the exterior of the shell. These extensions have numerous projections, or papillae, whose exact function is unknown, but which may increase the surface area for oxygen absorption or provide camouflage of some sort. Tiger cowries are nocturnal creatures, hiding in crevices among the coral during the day and emerging at night to graze on algae. The sexes are separate and fertilization occurs internally. Females exhibit some parental care in that they protect their egg capsules by covering them with their muscular foot until they hatch into larvae, which then enter the plankton to mature. DISTRIBUTION Swimming backward reduces drag from the tentacles. The siphon, used for jet propulsion, is clearly visible in this Humboldt squid. Tr 20m (66ft) ai la en insu Seward n Pe CONSULTANTS Low tide to 100 ft (30 m) on coral reefs and ﬂats Cyphoma gibbosum siphon Takoma Reef an 170˚E HABITAT Coral reefs at about 50 ft (15 m) REDUCING DRAG ti 16,400 ft (5,000 m) it Kuskokwim Bay Nunivak Island 4,024m (13,203ft) Ulm Bowers Seamount Plateau A Northwest Paciﬁc Basin 160˚E Aleutian Basin Komandorskiye Ostrova Ostrov Mednyy 6,088m (19,975ft) 4 Pervenets Canyon land Cordova S he h LENGTH SEEDING AN OYSTER The giant cuttleﬁsh’s color change is due to skin cells called chromatophores. It is pale when pigment is conﬁned to a small area of each cell. ˚N Mednyy Seamount 9,800 ft (3,000 m) C A N A D A Anchorage Et Up to 6 in (15 cm) The best-shaped artiﬁcial pearls are produced by “seeding” oysters with a tiny pearl bead and a piece of mantle tissue from another mollusk . 1 50 635m (2,083ft) er s Ku Hooper Bay Saint Matthew Island 285 HUMAN IMPACT Touch, smell, taste, and vision are well developed in many mollusks. The nervous system has several paired bundles of nervous tissue (ganglia), some of which operate the foot, and interpret sensory information such as light intensity. Photoreceptors range from the simple eyes (ocelli) seen along the edges of the mantle or on bivalve siphons, to the sophisticated image-forming eyes of cephalopods. Cephalopods are also capable of rapidly changing their color. cha e Mys Kam rr ac 7,864m Shipunskiy Te (25,802ft) 3 29m (95ft) Mys Olyutorskiy CLASS GASTROPODA three to five clearly visible holes in the shell, through which water flows for respiration.These are filled and replaced with new holes as the abalone increases in size. Sea otters are one of the red abalone’s main predators, along with human divers. MOLLUSKS Kamchatskiy Zaliv Ostrov Beringa Petropavlovsk- Kronotskiy Kamchatskiy Zaliv tka 12m (39ft) Olyutorskiy Zaliv Tiger Cowrie OCEAN LIFE The small, rounded, smooth, blackand-white striped shell of the zebra nerite is typical of the species, but in examples from Florida the shell is sometimes more mottled or speckled with black. These gastropods are most active during the day, when they feed on microorganisms such as diatoms and cyanobacteria, but if they become too hot or they are exposed at low tide, they cluster together, withdraw into their shells, and become inactive. This may be a mechanism for preventing excessive water loss. Unusually for gastropods, there are separate males and females of zebra nerites and fertilization of the eggs occurs internally. The males use their penis to deposit sperm into a special storage organ inside the female. Later, she lays a series of small white eggs that hatch into planktonic larvae. li v y Za i ns k Ostrov Karaginskiy Kamchatka Basin Mys Sivuchiy shaded area of map shows known natural range of species table of summary information (varies between categories) all distribution maps are accompanied by a written summary of the range of the species CONTRIBUTORS Richard Beatty Glossary Kim Bryan Introduction to Ocean Life, Bacteria and Archaea, Protists, Fungi, Mollusks, Arthropods, Red Crab Migration David Burnie Animal Life, Reptiles, Birds, Mammals Robert Dinwiddie Ocean Water, Circulation and Climate, Tides and Waves, Coasts and the Seashore, Shallow Seas, Polar Oceans, Ocean Yacht Racing, Shutting Down the Atlantic Conveyor, Hurricane Katrina, Global Warming and Sea-level Rise, Coastal Defenses, The Titanic Disaster Frances Dipper Introduction to Ocean Life, Sponges, Cnidarians, Segmented Worms, Flatworms, Ribbon Worms, Bryozoans, Echinoderms, Small Bottom-living Phyla, Planktonic Phyla, Tunicates and Lancelets, Jawless Fishes, Cartilaginous Fishes, Bony Fishes Philip Eales Ocean Geology, Atlas of the Oceans, Oceanography from Space, The Indian Ocean Tsunami, Ice-shelf Breakup Monty Halls Diving Tourism Sue Scott Shallow Seas, Red and Brown Seaweeds, Plant Life, Green Seaweeds, Green Algae, Mosses, Flowering Plants, Fishing Michael Scott The Open Ocean and Ocean Floor, Exploration with Submersibles, Cold Water Reefs, Biodiversity Hotspots, Whale Migration, Wind Farming in the Baltic The revised edition was prepared with the help of David Burnie (Ocean Life), Robert Dinwiddie (Introduction and Ocean Environments), Frances Dipper (Ocean Life), and Philip Eales (Atlas of the Oceans) AT L A S O F T H E O C E A N S LENGTH Up to 2 1/2 in (6 cm) HABITAT rag St DISTRIBUTION LENGTH Up to 1/2 in (1 cm) Rocky tide pools Paciﬁc The tropical carnivorous snail known as the Venus comb has a unique and spectacular shell. There are rows of long, thin spines along its longitudinal ridges, which continue onto the narrow, rodlike, and very elongated siphon canal. The exact function of these spines is unknown, but they are thought to be either for protection or to prevent the snail from sinking into the soft substrate on which it lives. Its body is tall and columnar so that it can lift its cumbersome shell above the sediment to move in search of food. Ka tk a Qu Nucella lapillus a cha 1,600 ft (500 m) 6,500 ft (2,000 m) go Dog Whelk Puperita pupa Eastern Indian Ocean and western s ul Ka m 1 800 ft (250 m) 500 miles 3,300 ft (1,000 m) ai Str cate He Zebra Nerite DISTRIBUTION nin sea level 400 ˚N 60 el a CLASS GASTROPODA e aP Ust’-Kamchatsk 110˚W 500 km 300 ip Tropical warm waters to 650 ft (200 m) CLASS GASTROPODA at k 400 200 r ch HABITAT ch Norton Sound 300 100 A LENGTH Up to 3 in (8 cm) 2 Saint Lawrence Island Mys Navarin Nome Norton Plain Khatyrka Ossora Cypraea tigris HABITAT Venus Comb L KEY 200 100 0 er Easily distinguished from most other gastropods by the conical shape of its spiral shell, the top shell moves slowly over reef flats and coral rubble, feeding on algae. Demand for its flesh and pretty shell has led to declining numbers, especially in the Philippines, due to unregulated harvesting. It has, however, been successfully introduced elsewhere in the Indo-Pacific, such as French Polynesia and the Cook Islands, from where some original sites are being restocked. LENGTH Murex pecten K 120˚W SCALE nd Reef ﬁsh, including Longﬁn Bannerﬁsh, Milletseed Butterﬂyﬁsh, and Bluestripe Snappers, swim around a table coral. 6–8 in (15–20 cm) CLASS GASTROPODA RETURNING HOME J 130˚W 140˚W UNITED STATES OF A MERICA a FRENCH FRIGATE SHOALS Rocks from low tide mark to 100 ft (30 m) Limpets gradually grind a “scar” into their anchor spot on the rock, to aid their grip and help retain water. A mucus trail leads them back to the spot. I Arctic Circle 0 Chirikof Basin Mys Chukotskiy Sea of Okhotsk In most cases, explanatory pages are followed by proﬁles of actual features. For example, the proﬁles shown here describe coral reefs from around the world. Most proﬁles are illustrated with color photographs. Haliotis rufescens The largest of the abalone species, the red abalone is so called because of the brick-red color of its thick, roughly oval shell. There is an arc of Fuca Plate west of Vancouver Island. The seamounts were created above the hotspot over the last 30 million years, then carried northwest by seafloor spreading. Since 1977, oil has been shipped through ports on the south coast of Alaska. In 1989, Prince William Sound was the site of one of the worst maritime environmental disasters, when the tanker Exxon Valdez ran aground, releasing about 30 million gallons (114 million liters) of crude oil. were born. The floor of the Gulf of Alaska is peppered with seamounts. There are two main chains: the Patton and Gilbert seamounts, and the Kodiak Seamounts, both running away from the Alaska Peninsula. Their origin is the Cobb Hotspot, situated beneath the spreading center of the Juan de H 150˚W 160˚W sk A wide fringing reef almost completely surrounds the shoreline of mountainous Moorea, part of which is visible in this view. Red Abalone East Paciﬁc coasts from southern Oregon, US to Baja California, Mexico G Good Bayhop Seward Peninsula la MOOREA CLASS GASTROPODA DISTRIBUTION ALASKAN FJORD The valleys and fjords of the Alexander Archipelago testify to extensive erosion by glaciers during the last ice age. xa Eastern Indian Ocean, western and southern Paciﬁc DISTRIBUTION The Cascadia Basin is the last remnant of the original eastern Pacific oceanic plate, the Farallon Plate, which has been almost entirely subducted beneath North America. The Cascade Range of volcanoes in Oregon and Washington State, including Mount St. Helens, are a product of this subduction. Mount St. Helens erupted in a catastrophic explosion in 1982, killing 57 people, and still shows signs of activity. Earthquakes and associated tsunamis are also a risk in the area, although the last major earthquake is thought to have been in 1700. The underlying ocean crust appears to be split into three small plates. The largest is the Juan de Fuca Plate, named after a Greek sea captain who explored the area for Spain in 1592. The Explorer Plate lies to the north and the Gorda Plate to the south. le The common limpet’s muscular foot, seen here from below, holds it ﬁrmly to its rock, regardless of the strength of the waves. taller shells allow for better water retention during periods of exposure. Limpets travel slowly during low tide, covering up to 24 in (60 cm) using contractions of their single foot. They graze on algae from rocks using a radula (a rasplike structure), which has teeth reinforced with iron minerals. Paciﬁc Ocean; Columbia, Fraser rivers INFLOWS A counterclockwise subpolar gyre extends across the north Pacific and into the Gulf of Alaska, fed by the warm waters of the northern Kuroshio Extension, the extension of the Kuroshio Current. The surface waters are cooled and become less saline due to precipitation as they cross the ocean. Many of the storms that lash the west coast of Canada originate in the Gulf of Alaska. The circulation is completed as the Alaska Current and the Aleutian Current return west along the Alaskan coast and south of the Aleutian Islands. The gulf ’s waters are very productive, providing feeding grounds for many species of fish. Pacific salmon spend up to five years at sea, much of it in the gulf and adjacent seas, before returning to spawn in the Asian and North American rivers where they a Str Abundant on rocks from the high to the low water mark, the common limpet is superbly adapted to shore life. A conical shell protects it from predators and the elements. Limpets living at the low water mark are buffeted by the waves and so require smaller, flatter shells than those living at the high water mark, where wider, 9,600 ft (2,930 m) INFLOWS n oli Northeastern Atlantic from Arctic Circle to Portugal DISTRIBUTION 66,000 sq. miles (170,000 sq. km) MAXIMUM DEPTH A ◀ FEATURE PROFILES Gulf of Anadyr idge rs R we Bo Intertidal and shallow subtidal areas, reef ﬂats to 23 ft (7 m) R US S I AN F EDER ATI ON ti HABITAT conical shell MUSCULAR FOOT F 170˚W Chukchi Sea Chukotskiy Poluostrov Anadyr’ se l A n Ri a 6 in (16 cm) HABITAT E Arctic Circle 180˚ dy r’ eu LENGTH DIAMETER 21/2 in (6 cm) Rocks on high shore to sublittoral zone D 170˚E 160˚E 150˚E Stra it ˚N ing 60 Al CLASS GASTROPODA Top Shell Tectus niloticus THE BERING STRAIT This satellite image shows ice from the Chukchi Sea streaming south through the Bering Strait. C 1 MOLLUSKS orange foot with greenish tint CLASS GASTROPODA Common Limpet AREA 16,400 ft (5,000 m) Susitna, Copper rivers; icebergs from numerous glaciers B er The Society Islands comprise a chain of volcanic and coral islands in the South Pacific, including islands with barrier reefs (such as Rai’atea), islands with both fringing and barrier reefs (such as Tahiti), and atolls or nearatolls (such as Maupihaa and Maupiti). The reefs’ biological diversity is moderate compared with the reefs of Southeast Asia, although more than 160 coral species, 800 species of reef fish, 1,000 species of mollusc, and 30 species of echinoderm have been ANIMAL LIFE Patella vulgata B e North-central Paciﬁc The Hawaiian Archipelago consists of the exposed peaks of a huge undersea mountain range. These mountains have formed over tens of millions of years as the Pacific Plate moves PACIFIC OCEAN L4 Cascadia Basin 600,000 sq. miles (1.5 million sq. km) CONDITION French Polynesia, northeast of New Zealand, south-central Paciﬁc R is LOCATION AREA MAXIMUM DEPTH LOCATION ev Coral disease outbreaks reported CONDITION Good, but signiﬁcant local damage where the contact is between ocean crust and continental crust. The largest volcanic event of the 20th century was the eruption of Mount Katmai on the Alaskan Peninsula in 1912. This boundary can also produce powerful earthquakes such as the event that destroyed part of Anchorage in 1964. ch 1,180 square km (450 square miles) AREA 1,500 square km (600 square miles) AREA SEALS IN THE ALEUTIAN ISLANDS ru Fringing reefs, atolls, submerged reefs TYPE 3 in (8 cm) per year Ob Hawaiian Archipelago northwest over a hotspot in the Earth’s mantle. Coral reefs fringe some coastal areas of the younger, substantial islands at the southeastern end of the chain, such as Oahu and Molokai. To the northwest, located on the submerged summits of older, sunken islands, are several near-atolls (such as the French Frigate Shoals) and atolls (such as Midway Atoll). These reefs are highly isolated from all other coral reefs in the world, and although their overall biological diversity is relatively low, many new species have evolved on them. The more remote reefs are healthy, but in 2013, a serious coral disease was reported affecting reefs on Oahu and Kauai. 26,600 ft (8,100 m) The Bering Sea is bounded to the south by the Aleutian Islands. On the Pacific side of the islands lies the Aleutian Trench, marking where the Pacific Plate is plunging beneath the North American Plate. It is this subduction zone that gives rise to the volcanic arc of islands, the most northerly link in the Pacific Ring of Fire. The trench continues to the east, OCEAN ENVIRONMENTS PACIFIC OCEAN CENTRAL 2,000 miles (3,200 km) RATE OF CLOSURE Amuk ta P a ss As with many Paciﬁc atolls, the rim of Majuro Atoll consists partly of shallow submerged reef and partly of small, low-lying islands. LENGTH Paciﬁc Ocean; Yukon, Anadyr’ rivers The Bering Sea is named after a Danish navigator in the Russian Navy, who explored the area in 1741. It lies between mainland Asia and North America, and is bounded by the Aleutian Islands to the south and linked to the Arctic Ocean in the north by the narrow Bering Strait. There is a flow of cold Arctic water south through this strait, feeding a counterclockwise circulation. The main freshwater input is the Yukon River, which has deposited an extensive delta at its mouth. The Bering Sea is one of the world’s richest fisheries, helping Alaska account PACIFIC OCEAN I3 Gulf of Alaska e MAJURO ATOLL Aleutian Trench 20,021 ft (6,102 m) aP ass Generally good; some episodes of coral bleaching CONDITION Fringing reefs, barrier reefs, atolls TYPE INFLOWS PACIFIC OCEAN MAXIMUM DEPTH 890,000 square miles (2.3 million square km) Am chi tk 6,200 square km (2,400 square miles) AREA Micronesia, southwest of Hawaii, western Paciﬁc LOCATION Society Islands AREA MAXIMUM DEPTH THE COLD, STORMY SUBPOLAR SEAS of the North Pacific are highly productive, supporting a rich fishery. Geologically, the area is dominated by a subduction zone, and the area’s volcanoes and earthquakes pose an ever-present danger. recorded. The reefs’ health is generally good, but some reefs around the busy holiday destination islands of Tahiti, Moorea, and Bora-Bora have been severely affected by construction, sewage, and sediment run-off. for about half of the total US fish and shellfish catch. Harbor seals and gray whales also take advantage of these productive waters. In contrast to the deep ocean basin beneath the southwestern half of the sea, the broad continental shelf in the northwest is very shallow. Much of this area formed a land bridge during the last ice age, when sea levels were up to 390 ft (120 m) lower than they are today. This route was ice-free for extended periods, allowing several species, including humans, to migrate from Asia to North America on foot for the first time. PACIFIC OCEAN D3 Bering Sea An a Humphead Parrotfish, and various species of octopuses and nudibranchs (sea slugs). Major threats to the reefs in Nusa Tenggara include pollution from land-based sources, removal of fish for the aquarium trade, and reef destruction by blast fishing. Coral bleaching affected some reefs in 2010. Atolls PACIFIC OCEAN SOUTHWEST 459 The Bering Sea And Gulf of Alaska ge TYPE The Marshall Islands consist of 29 coral atolls and five small islands in the western Pacific. The atolls lie on top of ancient volcanic peaks that are thought to have erupted from the ocean floor 50-60 million years ago. They include Kwajalein, the largest atoll in the Pacific at 2,500 square km (1,000 square miles), and Bikini and Enewetak atolls, which were used by the USA for testing nuclear weapons between 1946 and 1962. Human pressures on these two remote, evacuated atolls have been minimal during the past 50 years, and marine life around them now thrives; for example, 250 species of coral and up to 1,000 species of fish have been recorded at Bikini. THE PACIFIC OCEAN 458 One of the tiniest residents of the Great Barrier Reef, at just 7–8mm (less than 1⁄3in) long from snout to tail, is the Stout Infantfish. When discovered in 2004, the Infantfish was declared to be the world’s smallest vertebrate species. That title has since been claimed first by a slightly smaller species of Indonesian cyprinid fish, and more recently by a tiny species of frog, about 7mm (1⁄4in) long, found in Papua New Guinea. Rid Marshall Islands However, a study published in 2012 reported that the reef has lost more than half its coral cover since 1985. The factors causing this damage include pollution, tropical cyclones, raised water temperature causing mass coral bleaching, population outbreaks of the Crown-of-thorns Starfish, overfishing, and shipping accidents. THE WORLD’S SMALLEST VERTEBRATE? ov PACIFIC OCEAN SOUTHWEST In this view of a central area of the reef, a deep, meandering channel separates two reef platforms. The region’s high tidal range drives strong currents through such channels. sh lving coral f REEF CHANNEL ir Australia’s Great Barrier Reef, which stretches 2,010km (1,250 miles), is the world’s largest coral reef system. Often described as the largest structure ever made by living organisms, it in fact consists of some 3,000 individual reefs and small coral islands. Its outer edge ranges from 30 to 250km (18 to 155 miles) from the mainland, and its biological diversity is high. The reef contains about 350 species of stony coral and many of soft coral. Its 1,500 species of fish range from 45 species of butterflyfish, to several shark species, including silvertip, hammerhead, and whale sharks. The reef is also home to 500 species of algae, 20 species of sea snake, and 4,000 species of mollusc. 284 all maps are accompanied by a written description of location Damaged by tropical storms, pollution, and an unbalanced ecosystem CONDITION bbataha vers in the 1980s mage tices and ed farm. diversity of r example, n more more than mbined), reefimals here Rays, Barrier reef 37,000 square km (14,300 square miles) AREA Sh TYPE Em pe r or Se a mou nts he Philippines und two u Sea and e pelagic attracted nta Rays, eeply ch in pecies ibranchs 0 species Great Barrier Reef m Good; from coral n 2010 161 PACIFIC OCEAN SOUTHWEST Ka s square km e miles) In 1988, the Philippines government intervened, declaring the area a National Marine Park, and since 1993 it has also been a UNESCO World Heritage Site. The condition of the Tubbataha reefs has much improved, due to the enforcement of measures such as a prohibition on fishing and a ban on boats anchoring on the reefs (visiting craft must use mooring buoys). A setback occurred in January 2013 when a US Navy minesweeper ran aground on the reef, damaging over 2,000 square m (21,500 square ft). The final chapter of the book is an atlas of the world’s oceans. It includes maps of the five major oceans. The pages that immediately follow each whole-ocean map contain more detailed maps of selected regions of that ocean. All the maps have been produced using data collected from a combination of satellite- and ship-borne instruments. They are labeled to show the names of the seas, undersea features (such as ridges, trenches, and seamounts), and prominent coastal features. They also show ocean depths and ▼ REGIONAL MAP the boundaries between tectonic As well as maps, these pages also include plates. Features identified on the proﬁles of individual seas or undersea maps have been included in the features. The example shown here is from the section on the Paciﬁc Ocean. index at the end of the book. AT L A S O F T H E O C E A N S name of ocean in which feature is found compass direction indicates position within ocean FOREWORD W e should call our planet Ocean. A small orb floating in the endless darkness of space, it is a beacon of life in the otherwise forbidding cold of the endless universe. Against all odds, it is also the Petri dish from which all life known to us springs. Without water, our planet would be just one of billions of lifeless rocks floating endlessly in the vastness of the inky-black void. Even statisticians revel in the improbability that it exists at all, with such a rich abundance of life, much less that we as a species survive on its surface. Yet, despite the maze of improbability, we have somehow found our way to where we are today. Humans were enchanted by the sea even before the Greek poet Homer wrote his epic tale of ocean adventure, the Odyssey. It is this fascination that has driven us to delve into this foreign realm in search of answers, but the sea has always been reluctant to give up its secrets easily. Even with the monumental achievements of past explorers, scientists, and oceanographers, we have barely ventured through its surface. It is estimated that over 90 percent of the world’s biodiversity resides in its oceans. From the heartbeat-like pulsing of the jellyfish to the life-and-death battle between an octopus and a mantis shrimp, discoveries await us at every turn. And for every mystery solved, a dozen more present themselves. These are certainly exciting times as we dive into the planet’s final frontier. Aided by new technology, we can now explore beyond the two percent or so of the oceans that previous generations observed. But even with the advent of modern technology, it will take several more generations to achieve a knowledge base similar to the one we have about the land. No matter how remote we feel we are from the oceans, every act each one of us takes in our everyday lives affects our planet’s water cycle and in return affects us. All the water that falls on land, from the highest peaks to the flattest plains, ends up draining into the oceans. And although this has happened for countless millions of years, the growing ecological footprint of our species in the last century has affected the cycle in profound ways. From fertilizer overuse in landlocked areas, which creates life-choking algal blooms thousand of miles away, to everyday plastic items washing up in even the most remote areas of the globe, our actions affect the health of this, our sole life-support system. This statement is not here to make us feel that we are doomed by our actions, but rather to illustrate that through improved knowledge of the ocean system and its inhabitants, we can become impassioned to work toward curing our planet’s faltering health. By taking simple steps, such as paying a little more attention to our daily routines, each one of us can have a significant positive impact on the future of our planet and on the world our children will inherit. In short, it would be much healthier for us to learn to dance nature’s waltz than to try to change the music. MOVING EN MASSE The fast, coordinated movement of a shoal of ﬁsh is one of the most spectacular sights in the oceans. These blackﬁn barracuda have formed a spiraling shoal in water around the Solomon Islands. Such shoals are often found in the same place several months, or even years, apart. Fabien Cousteau GOLDEN JELLYFISH Drawn to the light, Jellyﬁsh in the genus Mastigias follow the sunlight around their brackish lake home in Palau. Stained golden-brown by algae in their tissues, they carry their photosynthetic passengers to the best-lit areas. In return, the algae provide them synthesized food. Isolated from the sea, these jellyﬁsh are found nowhere else in the world. NORTHERN EXPOSURE The world’s shorelines can be inhospitable places to live. Common murres nest in colonies, favoring rocky cliffs. These birds are clinging to a rock off the Scottish coast, while being battered by a ﬁerce gale. During the storm, many of the birds were swept off the rock and some of their eggs were washed into the sea. PROTECTION OF THE YOUNG The packhorse lobster inhabits the continental shelves off Australia and New Zealand. The female shown here is carrying eggs under her abdomen. Up to two million eggs at a time can be stored in this way. Despite producing eggs in such prodigious numbers, these lobsters are threatened by overﬁshing and catches are now restricted. FILTER-FEEDING WITH FEATHERS Instead of moving around in search of food, many marine animals spend their lives ﬁxed to the sea bed, collecting food as it drifts past. These feather-like funnels are actually part of the body of a worm. The worm beats tiny, hair-like structures to set up a current through the funnels and then traps food from the moving water. NEW COASTLINE The shape of a coastline is determined by a balance of forces. The coastlines of the Galápagos Islands in the eastern Paciﬁc are relatively new, having formed when the islands were created by volcanic eruptions. The lava seen here solidiﬁed about 100 years ago, but more recent eruptions have occurred on some of the group’s younger islands. THE FALL OF THE APOSTLES On this part of the southern Australian coast, marine erosion is the dominant force. A line of limestone cliffs is slowly being worn back by the sea, leaving behind isolated stacks of rock. The stacks are collectively known as the Twelve Apostles, although when they were named there were only nine of them and there are now just eight. LIVING ON THE BOTTOM The ﬂattened body of a ray is an adaptation for life on the bottom of the sea. Most rays feed on animals on the seabed, and so their mouths are on the undersides of their bodies. They have ﬂat teeth, which they use to grasp and then grind food. The features that resemble eyes are actually the ray’s nostrils. AVOIDING A STING Clownﬁsh have a remarkable relationship with some anemones, feeding and sleeping among them. The anemones’ stinging tentacles repel all other ﬁsh, but the clownﬁsh avoid triggering the ﬁring of the anemones’ stinging cells with an undulating swimming action and by secreting chemicals that suppress the ﬁring process. LEARNING TO SWIM Being able to swim is a useful skill for polar bears, which for part of the year track their prey across shifting sea ice in the Arctic Ocean and are sometimes seen in the water many miles from land. While underwater, they keep their eyes open but close their nostrils. They can remain submerged for up to two minutes. NUDIBRANCH Crawling over a vivid red seafan in the Komodo National park, Indonesia, this brightly colored nudibranch, or sea slug, stands out. Its scientiﬁc name, Phyllidia pustulosa, reﬂects the diseaselike nodules on its back. These yellow beacons warn ﬁsh that it contains toxins and they should not eat it. THE GREENLAND COAST In this satellite image of part of Greenland’s eastern coast, taken during a summer thaw, the brown areas are rocky land. Penetrating it are many long ﬁords, some partly ﬁlled by glaciers and large, ﬂat icebergs. Other icebergs of varying size, formed from a disintegrated ice shelf, ﬂoat offshore in vast numbers. INTRODUCTION EARTH’S OCEANS CONTAIN about 320 million cubic miles (1.34 billion cubic kilometers) of seawater. Dissolved in this are some 53 million billion tons (48 million billion metric tons) of salts, gases, and other substances. The base substance, water itself, has many unusual properties, such as its high surface tension and heat capacity, which are of tremendous signiﬁcance to everything from the oceans’ ability to support life to their stabilizing effect on the world’s climate, and their ability to transmit waves. Also of signiﬁcance is the variability of ocean water—the sea is not uniform but varies spatially and sometimes seasonally in attributes such as its temperature, pressure, dissolved-oxygen content, and level and quality of light illumination. These attributes are important in numerous key respects. OC E A N WAT E R CRASHING WAVE This “barrel” wave is crashing onto the north shore of the island of Oahu, Hawaii. Inspiring sights such as this are only possible because of some of the unusual properties of water. 30 OCEAN WATER hydrogen atom consists of one proton and one electron The Properties of Water hydrogen nucleus, consisting of single proton, contains positive charge THE MAIN CONSTITUENT OF THE OCEANS IS, of course, water. The presence of large amounts of liquid water on Earth’s surface over much of its history has resulted from a fortunate combination of factors. Among them are water’s unusually high freezing and boiling points for a molecule of its size, and its relative chemical stability. Water also has other remarkable properties that contribute to the characteristics of oceans—from their + + ability to support life to effects on climate. Underlying these properties is water’s molecular structure. water molecule – region of slight negative charge hydrogen bond The Water Molecule hydrogen bond + + – – + + region of slight positive charge – + shared electron one of eight electrons in oxygen atom oxygen atom free A molecule of water (H2O) consists of two hydrogen (H) electron atoms bound to one atom of oxygen (O). Crucial to formation of the bonds between the oxygen and hydrogen atoms are four tiny negatively charged particles called electrons, which are shared between the atoms. In addition, six other electrons move around HYDROGEN BONDS within different regions of the oxygen atom. This A hydrogen bond is an electron arrangement makes the H2O molecule attractive electrostatic chemically stable but gives it an unusual shape. It also force between regions of produces a small imbalance in the distribution of slight positive and negative charge on neighboring water electrical charge within the molecule. An important molecules. Several bonds result of this is that neighboring water molecules are are visible here. drawn to each other by forces called hydrogen bonds. oxygen nucleus, containing protons and neutrons, has positive charge CHARGE IMBALANCE The distribution of negative charges (electrons) and regions of positive charge in an H2O molecule causes one side to carry a slight positive charge and the other side a slight negative charge. water molecule at surface WALKING ON WATER INTRODUCTION Certain insects, such as sea skaters and water striders (pictured below), exploit surface tension to walk, feed, and mate on the surface of the sea, lakes, or ponds. Surface Tension hydrogen bonds One special property of liquid water that can be directly attributed to the attractive forces between its molecules is its high surface tension. In any aggregation of water molecules, the surface molecules tend to be drawn together and inward toward the center of the aggregation, water forming a surface “skin” that is resistant to disruption. Surface molecule tension can be thought of as the force that has to be exerted below surface or countered to break through this skin. Water’s high surface tension has various important effects. Perhaps the most crucial is that it is vital to certain processes within living organisms—for example, water transport in plants and blood transport in animals. Surface tension also allows small insects such as sea skaters to walk and feed on the ocean surface, and it even plays a part in the formation of ocean waves (see p.76). CAUSE OF SURFACE TENSION In a drop of water, molecules are pulled in all directions by hydrogen bonding with their neighbors. But at the surface, the only forces act inward, or sideways, toward other surface molecules. WATER DROPLETS The shape of these droplets results from surface tension. The forces pulling their surface molecules together are stronger than the gravitational forces ﬂattening them. THE PROPERTIES OF WATER LAND AND SEA 31 Heat Capacity Water’s high heat capacity means that the Sun warms the sea more slowly than land. In this satellite-generated temperature map of south California during a heat wave, much of the land (red) is 122ºF (50ºC) or more, but the sea (left) is cool, at 50ºF (10ºC). A second property of liquid water that can be attributed to hydrogen bonding is its unusually high heat capacity, which exceeds that of nearly all other known liquids (see table, left). When heat is added to water, most of the heat is used to break hydrogen bonds linking the molecules. Only a fraction of the energy increases the vibrations of the water molecules, which are detected as a rise in temperature. This means that areas of ocean can absorb and release huge amounts of heat energy with little change in temperature. It also means that movements of water— ocean currents—transfer enormous amounts of heat energy around the planet. This role of ocean currents is vital to Earth’s climate (see p.66). SPECIFIC HEAT CAPACITY Speciﬁc heat capacity (SHC) is the energy (in joules) needed to raise the temperature of 1 gram of a substance by 1ºC. Listed below are the SHCs of 13 liquids, measured at room temperature unless otherwise stated. SUBSTANCE JOULES/GRAM ºC Liquid ammonia at –40ºF (–40ºC) 4.7 Fresh water 4.19 HEAT ON THE MOVE Seawater at 35ºF (2ºC) 3.93 In this temperature map of part of the northwest Atlantic, the water surface ranges from about 41ºF (5oC) (blue) to 77ºF (25ºC) (red). A warm current, the Gulf Stream is visible in red. Glycerin 2.43 Ethanol (ethyl alcohol) 2.4 Acetone 2.15 Kerosene 2.01 Olive oil 1.97 Benzene 1.8 Turpentine 1.72 Freon 12 refrigerant at -40ºF (-40ºC) 0.88 Bromine 0.47 Mercury 0.14 WATER TWISTER The effects of surface tension can cause moving sheets, jets, and streams of water to assume or hold together in some surprising forms, as in this slightly spiral-shaped water jet. Three States of Water The temperatures at which water changes between its three states— melting point (ice to liquid water) and boiling point (liquid water to water vapor)—are both high compared with substances having similarly sized molecules. For ice to melt and water to vaporize, high levels of energy are needed to break all the hydrogen bonds. Water is also unusual in that its solid form is slightly less dense than its liquid form, so ice floats in liquid water. The reason for this is that the molecules in ice are loosely packed, whereas those in liquid water move around in snugly packed groups. The fact that ice floats on liquid water is important because it allows the existence of large areas of polar sea ice (see pp. 198–199). These affect heat flow between ocean and atmosphere and help stabilize ocean temperatures and Earth’s climate. SOLID, LIQUID, AND GAS ICE LIQUID WATER WATER VAPOR Hexagonal crystal lattice Small clumps of bonded molecules Widely spaced unbonded molecules In ice, hydrogen bonds hold the water molecules together in a rigid structure. In liquid water, the bonds hold the molecules in small, moving clumps. In water vapor, there are no hydrogen bonds. Water is the only natural substance found in all three states at Earth’s surface. Sometimes, ice, liquid water, and condensing water vapor can be seen side by side, as here at the fjord in Spitsbergen. INTRODUCTION SIDE BY SIDE 32 OCEAN WATER The Chemistry of Seawater volcanic ash drifts down to sea THE OCEANS CONTAIN MILLIONS OF DISSOLVED chemical substances. Most of these are present in exceedingly small concentrations. Those present in significant concentrations include sea salt, which is not a single substance but a mixture of charged particles called ions. Other constituents include gases such as oxygen and carbon dioxide. One reason the oceans contain so many dissolved substances is that water is an excellent solvent. The Salty Sea salts are leached from rocks into rivers and streams and ﬂow to ocean The salt in the oceans exists in the form of charged particles, called ions, some positively charged and some negatively charged. The most common of these are sodium and chloride ions, the components of ordinary table salt (sodium chloride). Together they make up about 85 percent by mass of all the salt in the sea. Nearly all the rest is made up of the next four most common ions, which are sulfate, magnesium, calcium, and potassium. All these ions, together with several others present in smaller quantities, exist throughout the oceans in fixed proportions. Each is distributed extremely uniformly—this is in contrast to some other dissolved substances in seawater, which are unevenly distributed. salt spray onto land nutrients from soil wash into rivers and streams, and ﬂow to ocean BREAKDOWN OF SALT If 2½ gallons (10 liters) of seawater are evaporated, about 123/4 oz (354 g) of salts are obtained, of the types shown below. 2½ gallons (10 liters) of seawater other salts 1/4oz (7.5g) calcium sulfate (gypsum) 2/3oz (17.7g) magnesium salts 2oz (54.8g) sodium chloride (halite) 10oz (274g) + + + – – + – Na+ – – – – + WATER AS A SOLVENT + slow uplift of sedimentary rocks at continental margins, exposing salts, minerals, and ions at surface – sodium chloride crystal + – + + Cl– + water molecule + ALEXANDER MARCET The Swiss chemist and doctor Alexander Marcet (1770–1822) carried out some of the earliest research in marine chemistry. He is best known for his discovery, in 1819, that all the main chemical ions in seawater (such as sodium, chloride, and magnesium ions) are present in exactly the same proportions throughout the world’s oceans. The unchanging ratio between the ions holds true regardless of any variations in the salinity of water and is known today as the principle of constant proportions. + – + + – – PEOPLE uptake of nutrients by phytoplankton – – chloride ion (negative charge) INTRODUCTION + – + The charge imbalance on its molecules makes water a good solvent. When dissolving and holding sodium chloride in solution, the positive ends of the molecules face the chloride ions and the negative ends face the sodium ions. sodium ion (positive charge) – Sources and Sinks nutrient upwelling exchange of gases between phytoplankton and seawater sinking and decomposition The ions that make up the salt in the oceans have arrived of dead there through various processes. Some were dissolved out of organisms rocks on land by the action of rainwater and carried to the sea in rivers. Others entered the sea in the emanations of hydrothermal vents (see p.188), in dust blown off the land, or came from volcanic ash. There are also “sinks” for every type of ion—processes that remove them from seawater. These range from salt spray onto land to the precipitation of various ions onto the seafloor as mineral deposits. Each type of ion has a characteristic residence time. This is the time that an ion remains in seawater before it is removed. The common ions in seawater have long residence times, ranging from a few hundred years to hundreds of millions of years. RIVER DISCHARGE River discharge is a mechanism by which ions of sea salt and nutrients enter the oceans. Here, the Noosa River empties into the sea on the coast of Queensland, Australia. THE CHEMISTRY OF SEAWATER SOURCES, SINKS, AND EXCHANGES spread of volcanic ash and gases into rain clouds Shown here are various sources, sinks, and exchange processes for the ions, salts, and minerals (yellow arrows), gases (pink arrows), and plant nutrients (turquoise arrows) in seawater. KEY 33 Gases in Seawater gases ions, salts, and minerals plant nutrients The main gases dissolved in seawater are nitrogen (N), oxygen (O2), and carbon dioxide (CO2). The levels of O2 and CO2 vary in response to the activities of photosynthesizing organisms (phytoplankton) and animals. The level of O2 is generally highest near the surface, where the gas is absorbed from the air and also produced by photosynthesizers. Its concentration drops to a minimum in a zone between about 660 ft (200 m) and 3,300 ft (1,000 m), where oxygen is consumed by bacterial oxidation of dead organic matter and by animals feeding on this matter. Deeper down, the O2 level increases again. CO2 levels are highest at depth and lowest at the surface, where the gas is taken up by photosynthesizers faster than it is produced by respiration. CARBON SINK washing of ions from volcanic dust and gases into sea, dissolved in rain Many marine animals, such as nautiluses (below), use carbonate (a compound of carbon and oxygen) in seawater to make their shells. After they die, the shells may form sediments and eventually rocks. dust blown off land exchange of gases between animals and seawater exchange of gases between ocean and atmosphere OXYGEN PRODUCER AND CONSUMER Oxygen levels in the upper ocean depend on the balance between its production by photo-synthesizing organisms, such as kelp, and its consumption by animals, such as ﬁsh. Nutrients release of minerals from hydrothermal vents dissolving of minerals from sea ﬂoor precipitation of minerals onto sea ﬂoor PLANKTON BLOOM This satellite image of the Skagerrak (a strait linking the North and Baltic seas) shows a bloom of phytoplankton, visible as a turquoise discoloration in the water. SILICEOUS DIATOMS These tiny forms of planktonic organisms have cell walls made of silicate. They can only grow if there are sufﬁcient amounts of silica present in the water. INTRODUCTION carbonates incorporated into seaﬂoor sediments from animal shells Numerous substances present in small amounts in seawater are essential for marine organisms to grow. At the base of the oceanic food chain are phytoplankton—microscopic floating life-forms that obtain energy by photosynthesis. Phytoplankton need substances such as nitrates, iron, and phosphates in order to grow and multiply. If the supply of these nutrients dries up, their growth stops; conversely, blooms (rapid growth phases) occur if it increases. Although the sea receives some input of nutrients from sources such as rivers, the main supply comes from a continuous cycle within the ocean. As organisms die, they sink to the ocean floor, where their tissues decompose and release nutrients. Upwelling of seawater from the ocean floor (see p.60) recharges the surface waters with vital substances, where they are taken up by the phytoplankton, refueling the chain. 34 OCEAN WATER Temperature and Salinity OCEAN WATER IS NOT UNIFORM BUT VARIES in several physical attributes, including temperature, salinity, press