Oceans by Hutchinson & Hawkins
Ref: Stephen Hutchinson & Lawrence Hawkins (2005). Oceans: A Visual Guide. Firefly Books.
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Summary
Oceans contain habitats as different from one another as rainforest is from desert. From coastline to deepest ocean trench their lives a vast array of marine life- some rare, some bizarre, some of astonishing beauty- that has adapted to extreme and extraordinary conditions. Oceanography, the study of the oceans, is little more than a century old but in that time, we have developed ways to scan the sea from space to help us understand temperature and currents, and oceanographers can descend in submersibles to study the geology of the seafloor. Oceans is a rich visual guide to the world’s oceans- their formation and extent, the life forms they support, their value to humans, and the threats they face- complemented by stunning photography and detailed illustrations.
This reference features:
The blue planet: a dynamic water world that harbors life.
Exploration, mythology, archaeology and the emergence of oceanography.
A survey of marine plants and animals in oceanic habitats.
The dark, deep seafloor and biodiverse ocean fringes.
Oceans as a human habitat, food supply and dumping ground.
Factfiles, glossary, ocean category tables and more.
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The Blue Planet
The surface of Earth has evolved, during the 4,600 million years of its life, from a totally molten planet to one with a hard skin. Today, the outer skin, or crust, is comprised of either continents or ocean floor. Large, rigid areas of Earth's crust are called tectonic plates and are constantly moving and reshaping the continents and oceans. When Earth's crust solidified sufficiently to enable oceans to form, the water in them came from two sources. The first was steam and other gases vented by volcanic activity deep in Earth's mantle over millions of years. The second source was extraterrestrial. It is estimated that between 5 and 30 icy comets, up to 12 m across, strike the atmosphere every day. There are also satellite observations of much larger space snowballs vaporizing and adding water to the ocean. Some scientists have suggested that at one stage, the early Earth was entirely covered by water.
Ocean basins formed about 4.5 Ga. By 200 Ma, Earth had one superocean (Panthalassia) surrounding a single supercontinent (Pangea), and a sea (Tethys Sea that later became the Mediterranean. Pangea broke up around 150 Ma to form Gondwana and Laurasia, which opened up the North Atlantic. A rift opened in Gondwana 130 Ma to form the Indian Ocean. Around the same time, a semi-enclosed sea (the Sinus Borealis) on the northern edge of Pangea started to widen into the Arctic Ocean. The South Atlantic basin started to develop and join the North Atlantic 95 Ma, in the process shrinking Panthalassia into part of the Pacific Ocean. By 15 Ma, the oceans had arrived at approximately their present form. In 50 million years from now, the Mediterranean will have disappeared as Africa and Europe join, and the Atlantic Ocean will have become wider.
Atlantic Ocean: A = 86.9M km2, Zavg = 3605m (Zmax = 8605m).
Indian Ocean: A = 70M km2, Zavg = 3854m (Zmax = 7544m- Java Trench).
Pacific Ocean: A = 169.8M km2, Zavg = 4001m (Zmax = 11034- Mariana Trench).
Southern Ocean: A = 20.3M km2, Zavg = 3854m (Zmax = 7235m- Sandwich Trench).
Arctic Ocean: A = 14M km2, Zavg = 1430m (Zmax = 5625m).
Seawater is ~1.03x heavier than freshwater at the same temperature.
Average Ocean Salinity is between 33-37ppt.
Neap Tides: Occur when the moon is in either its first or its last quarter- when its gravitational pull on the oceans is at right-angles to the sun. This reduces the high tides and the depth of low tides.
Spring Tides: Occur when the moon is new or full and aligned with the Sun, which reinforce each other so that the tidal range is greatest.
Water Movement: Seawater becomes denser when it is cold and its salinity is increased. Multiplying this up to ocean scales generates enormous forces that can move immense volumes of water. Cooling at high latitudes causes denser cold water to sink and travel slowly away from the poles as deep and bottom water masses, eventually rising and returning in the upper layers in counter currents.
El Niño La Niña: This oceanographic and weather phenomenon is centered around the western coasts of Central and South America. It takes its name from the Spanish for the Christ child, since it commences around Christmas every 3-8 yrs. In non-El Niño years, the trade winds drag huge volumes of surface water westward, away from the coast. This allows the cold, nutrient-rich waters of the Peru Current to reach the surface near the coast. These waters support rich supplies of plankton that are vital to sustaining the local fisheries and vast numbers of seabirds. In an El Niño event, for reasons that are still not clear, the trade winds slacken and warm water remains at the coast. This water blocks the upwelling of the Peru Current so that there is no significant plankton production. Fishes and birds either die of starvation or go elsewhere. In recent years, it has been realized that these events also cause changes in global weather patterns. In the severe El Niño event of 1997-98, there were exceptional tornadoes in the American southwest because of the extra warming of air masses by the coastal warm water. Droughts in Papua New Guinea, Hawaii and SW Africa occurred because the normal flow of moist, rain-producing air in the trade winds was blocked.
Hurricane: Caused by the interaction of the oceans and atmosphere. Known as cyclones in the Indo-Pacific region and typhoons in Japan, they form over warm, tropical waters, most often between 5-15 degrees latitude, slightly away from the equator. The warm water heats the air above, giving rise to clouds that become clusters of thunderstorms. The rotating storm system spins progressively quicker as it moves away from the equator. A storm must produce winds >119 km/h (74mph) to be classified as a hurricane. Once formed, it may last days or even weeks before sweeping poleward or crossing over land, often with disastrous results. Its severity and potential to do damage on land are rated on the five-point Saffir-Simpson scale. Hurricanes frequently extend a great distance up into the atmosphere and can measure as much as 970 km across.
Saffir-Simpson Scale
1: >980 hP, 118-152 kph, 1.2-1.6m storm surge, minimal damage.
2: 965-979 hP, 153-176 kph, 1.7-2.5m storm surge, moderate damage.
3: 945-965 hP, 177-208 kph, 2.6-3.7m storm surge, extensive damage.
4: 920-944 hP, 209-248 kph, 3.8-5.4 m storm surge, extreme damage.
5: <920 hP, >248 kph, >5.4 m storm surge, catastrophic damage.
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Exploring the Oceans
Latitude: Determined by simple observations of the Pole Star.
High Arctic Indigenous Peoples: Several closely related groups of people native to the high Arctic are found around the shores of the Arctic Ocean, and include the Inuit, Inupiat, Yupik and Alutiit. These are regional names that mean "the people" or "the real people." Today, the Arctic peoples of Canada and Greenland prefer to be known as Inuit (their distribution is shown, left, while the indigenous groups in Alaska refer to themselves as Eskimo, as do some of the indigenous peoples across the Bering Strait in Siberia. The origins of the peoples of the high Arctic are not clear, but archaeologists have found artefacts dating back around 3000 years on Umnak Island in the Aleutians, Alaska.
Inuit: Indigenous peoples of the Arctic and subarctic regions of Greenland, Alaska, Canada and far-eastern Russia (Siberia). They adapted over centuries to life in a polar climate by becoming almost totally reliant on the sea to supply their food and other needs. The lack of significant vegetation meant that caribou, seal, walrus, whale meat, whale blubber and fishes were their major food sources, as well as the source of raw materials for clothing, tents and boats. Seals were hunted from ice floes or from skin-covered kayaks. Harpooning whales required several people; it was done from larger craft known as umiaks. Families lived in hide tents in summer, and hunted caribou and other land animals with bows and arrows. They lived in snow-block igloos in winter, or in wood- or whalebone-frame-worked houses dug into the ground and covered by stone or turf. During the 20c, contact with industrialized societies to the south brought major changes to Inuit life. The seminomadic life has now been largely abandoned, and many Inuit live in northern towns and cities. Out on the ice, snowmobiles have replaced traditional dogsleds, and hunting is done with a rifle.
It is thought that the remote islands of the Pacific were first reached by humans in a succession of migrations from the mainland of SE Asia and its long archipelago of islands. The first wave of exploration and settlement carried people to New Guinea, the New Hebrides and New Caledonia (Melanesia). Later generations moved northward to the Marshall and Gilbert Island groups (Micronesia), and then went eastward into the vastness of the Pacific and Polynesia. Beginning 4000 years ago, the Pacific migrations finished around 1000 years ago with the Māori settlement of New Zealand. The longest voyages took these early Pacific explorers as far east as the Marquesas Islands. From there, they ventured as far north as Hawaii, sometime between AD 450 and 600. They also sailed as far south as Easter Island. This remarkable dispersion over the Pacific was possible only because of the early development of large, seaworthy, sailing canoes, coupled with exceptional navigational skills.
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Ocean Life
At the base of any food web, all but a few ecosystems depend on plants to trap solar energy and produce new plant material from nutrients. In marine ecosystems, the bulk of solar energy is taken up by phytoplankton, with a small contribution from seaweeds, sea-grass beds and mangroves. In turn, this plant material is either grazed by zooplankton and larger filter feeders, or dies and falls to the bottom to provide food for organisms on the seabed. Zooplankton, in their turn, are grazed by larger animals and, like the phytoplankton, when they die they also carry organic matter down to the seabed. Material and energy are also taken out of the marine food web by seabirds. The quantity of material that flows up the food web decreases at every level; this limits the numbers of top-level consumers that the ecosystem can sustain. In their turn, these animals return material to the bottom of the food web through their waste products and decayed matter when they die.
Trophic Pyramid: In the food web, energy and materials flow from a broad base of billions of small producers through a decreasing number of larger organisms to a few top consumers. ~10% of the energy entering each level is passed up to the next. Energy and materials at the top of the pyramid are, therefore, a fraction of those represented by the primary producers.
Plankton: The microscopic plants and small animals that spend all or part of their lives floating in midwater, drifting passively in the currents and eddies of the world's oceans.
Phytoplankton: Planktonic plants that are mainly single-celled algae. Because they require sunlight to live, they are restricted to the surface layers of the oceans, down to ~100m.
Zooplankton: Planktonic animals that are found at all depths, grazing on phytoplankton or plant and animal remains that sink down from the surface. Zooplankton consist of two types of animals: those that live out their lives in the water column (holoplankton); and those that spend part of their early lives feeding and drifting in the water before developing into the adult form away from their parents (meroplankton).
Sponges: Among the simplest forms of sea creatures; they are little more than a loose association of cells organized into filter-feeding structures, and are found attached to the seafloor or to other marine surfaces. The main groups of sponges are classified according to the amount of folding of the body, which is one of the few consistent features in sponge body forms. Sponge cells exhibit some remarkable properties. If a sponge is completely broken up and the resulting slurry is left for a few hours, the cells will reorganize into a similar, although not identical, body form. Sponge cells are bound together by fibers of an elastic protein known as spongin. The body is given greater rigidity by the production of embedded mineral spicules, made of CaCO3 or silica, that enable some species to grow very large. Sponges vary from small, irregular forms to very large barrels and tubes.
All sponges have the same basic internal structure. Water is drawn into the sponge through pores (ostia) connected to a network of internal canals. The current is created by the beating of microscopic hairs on cells (or choanocytes) that are grouped together in feeding chambers. Food particles are trapped in these chambers and taken up by surrounding cells. Waste products are expelled with the filtered water that leaves the sponge via pores called oscula. A sponge is able to filter its own volume rapidly, usually every 4-20 sec.
Seaweeds: Marine algae; they differ from land plants in lacking roots, flowers, seeds and fruit. They anchor themselves in place by means of a suckerlike structure called a holdfast.
Green Algae: The simplest form of seaweed; consists of strings or sheets of algal cells; as their name suggests, they are often a vivid green.
Brown Algae: Include some of the largest, most complex forms of seaweed, such as the giant kelp that grows to great lengths and forms dense forests offshore. Their pigments are more sensitive to low light levels and enable them to live in deeper water than most other seaweeds.
Red Algae: The most diverse of the seaweeds in terms of number of species. They range from large fronds to encrusting, coral-like forms and include edible species, such as those used in Japanese cuisine.
Cnidarians: Corals, jellyfishes & anemones; they exhibit two body forms: the polyp, characteristic of corals and sea anemones, and the medusa form of jellyfishes. Cnidarians have stinging cells that capture prey or pick particles from the water. Most species are harmless to humans, but a few have venom that can cause severe injury or death.
Corals: Live in colonies and secrete a hard CaCO3 skeleton around themselves. Over centuries, successive generations have gradually formed massive reefs. Coral reefs need clear water where sunlight can penetrate to the bottom to allow the process of photosynthesis to occur. Polyp colonies that lift themselves up off the sea bottom on a branching protein skeleton are known as sea fans. The highly prized precious or red coral is a sea fan that has pink or red chalky material embedded in the protein skeleton.
Sting Cells: Triggered either by direct contact or by chemicals released by the prey or potential predator when in close proximity to the sting cell. Once triggered, the fluid in the cell rapidly absorbs water, and muscle fibers around the cell contract. This combination of events causes a sudden increase in the internal pressure of the cell, and forces fluid up the hollow center of the venom-tipped thread coiled within. The inflating sting bursts out of the top of the cell. It does so with sufficient force to drive its fine tip into the prey's skin and inject venom. Most jellyfish species are harmless to humans, but the toxicity of a few can cause death.
Comb Jellies (Ctenophores): Radially symmetrical and look like true jellyfishes. However, they are a completely separate group, consisting of ~100 species, and are exclusively marine. Comb jellies have a transparent, gelatinous body that, under normal lighting, is difficult to see. Often, the only visual indications of their presence are eight rows of cilia over the body that beat in coordinated waves. These are referred to as ciliary combs and they refract light, giving rise to a shimmering rainbow of colors as they beat. Comb jellies range from minuscule to up to 2 m long. All are carnivorous and most feed on zooplankton caught using two long tentacles. The tentacles are covered in sticky, or lasso, cells, which hold on to prey. Only one rare species is known to have sting cells. Most species are active swimmers and live in the water column. A small number, the purse jellies, live on the seabed.
Marine Worms: The simplest are visible to the naked eye are the flatworms (platyhelminths). They have flat bodies symmetrical along their long axis, and a head with well-developed sense organs. However, they have a blind-ended gut like jellyfishes and sea anemones, and they do not have gills or a blood system. Many tropical species are brightly colored to warn potential predators that they contain noxious chemicals. Some can even extract undischarged sting cells from sea anemones for use in their own bodies. The ribbon, or nemertean, worms are similar to the flatworms but have a gut with a mouth and anus, enabling them to feed more efficiently and to grow many times larger. They are active carnivores, hunting small animals buried in soft mud and sand. One of the most remarkable characteristics of the ribbon worms is their ability to change length. The bootlace worm found on northern temperate shores is often 10 m long when moderately contracted, but it can expand to more than twice that length. Most marine segmented, or annelid, worms are in a group known as the polychaetes. These have a very wide variety of body forms and lifestyles. Some are active predators above or below the sediment surface; others are fixed in tubes and filter feed. All have bodies composed of repeating segments. The peanut, or sipunculan, worms are distant relatives of the annelids, but they lack segmentation and have well-developed organ systems.
Lophophorates: Sea mats, lamp shells and horseshoe worms are three phyla of mainly marine invertebrates. They all have an unusual filter-feeding structure, called a lophophore, that looks like a curved or coiled brush. These animals have different body forms and life histories, but they also share many characteristics.
Sea Mats (Bryozoans): The largest group of lophophorates. There are some 5000 species. Sea mat colonies are comprised of individuals called zooids that collaborate to make a skeleton in which they live. This can be either an encrusting patch on rocks or seaweeds, or lacy colonies that resemble bleached seaweed.
Lamp Shells (Brachiopods): Resemble ancient pottery lamps or bivalves, but the presence of a long fleshy stalk and the lophophore indicates their true identity.
Horseshoe Worms (Phoronids): Get their name from the distinctive horseshoe shape of their lophophore. They live worldwide in tubes built of sand grains that are attached to hard surfaces in shallow water.
Mollusks: A diverse group of animals whose origins lie in the ancient seas of the Precambrian era > 1 Ga. Today, the most primitive form of marine mollusk is the chiton. Its body is covered by eight interlocking, hinged chalky plates.
Gastropods: The largest group of mollusks that include sea slugs, snails and limpets. They have, or have had in their evolutionary history, a single calcareous shell. The sea slugs lost their armorlike shell over time and rely on warning coloration and chemical defenses.
Sea Slugs: Often colorful and have feathery gills or other ornamentation on their backs.
Snails & Limpets: Have shells in a great variety of sizes, shapes, colors and degrees of ornamentation. A small number of gastropods adapted to life in the water column. They either extended their foot into a winglike structure, as in the sea butterflies, or, like the purple sea snail, secreted a raft of bubbles from which to hang and catch their jellyfish prey.
Bivalves: A group of mollusks that have evolved a hinged shell and have largely abandoned locomotion. Most bivalves are filter feeders. A few, such as the ship worm, are borers that feed on wood and detritus.
Cephalopods: The most advanced mollusks which include octopus and squid. These active hunters use their acute senses and camouflage to ambush prey.
Crustaceans: The common features of all the arthropods are a hard, often armored, external skeleton, or exoskeleton, jointed legs and feeding appendages. The exoskeleton provides the animal with a high degree of protection, and has allowed the development of powerful muscles. It limits the creature's size, however, because it has to be lost periodically by molting to allow the soft tissue to expand and grow. In the oceans, crustaceans have gills for respiration and an exoskeleton reinforced with calcium carbonate absorbed from the surrounding water. There may be as many as 45K species of crustaceans and they are found in all major marine habitats. Scientists regard them as the marine equivalent of the dominant terrestrial arthropods-the insects.
Echinoderms: Starfishes, feather stars, sea cucumbers and sea urchins-form one of the largest groups of invertebrate animals in the sea. There are ~60K species, all of which live in marine habitats-from warm tropical waters to icy polar seas, and from the shoreline to the bottom of the deepest ocean trenches. The body forms of all echinoderms are variations on a simple theme. They are radially symmetrical and have five arms, although these may be lost or modified while they develop. The basic body plan is seen in the starfish. The feather stars can be thought of as starfishes living upside down, with the upturned arms reduced to flexible, feathery stalks that beat in the water. The sea cucumbers have fused their arms to form a cylinder. Their soft, leathery bodies enable them to move in small crevices. Sea urchins have fused their arms to form a hollow disk of hard, chalky plates. Most echinoderms feed on small particles in the water, but some are active predators of bivalve mollusks and corals.
Sea Squirts & Lancelets: A distant cousin to humans, as they are in the same phylum (chordates). All 49K species of living chordates share three important characteristics. During development, each one has a single, hollow nerve chord, gill slits and a flexible rod (notochord) to support the nerve cord. What distinguishes humans and other animals that are described as vertebrates is that the notochord is replaced by, or incorporated into, a true jointed backbone. Sea squirts and lancelets do not have a backbone at any stage so are technically invertebrates. Adult sea squirts are filter feeders. Water is drawn into the mouth, or inhalant siphon, by the beating of cilia that cover a sievelike basket at the front end of the gut, and the openings are derived from gill slits in the larva. Food particles are trapped on the mucus that covers the sieve and are eventually drawn in a string into the gut. Filtered water and waste pass out of the animal through a second exhalant siphon. Some sea squirts are found as colonies on hard surfaces. The salps are sea squirts that have gone back into the water column, either as individuals or as ribbonlike colonies. The lancelets are invertebrate chordates found in soft sediments in shallow water.
Lampreys: Lampreys are found in temperate freshwaters of the northern and southern hemispheres, but some species spend part of their adult lives in the sea. Adult lampreys can be either non-parasitic or parasitic. The non-parasitic species are called brook or dwarf lampreys. After a larval stage lasting as long as 7 yrs, they do not feed before spawning and dying. The parasitic species may live for a further three years after metamorphosis and grow to 90 cm. These parasitic forms stay in freshwater or migrate to the ocean.
Hagfishes: Exclusively marine in temperate zones but also occur in the cool, deep waters of the tropics. Unlike lampreys, hagfishes do not have a larval phase but produce large, yolky eggs that hatch into miniature versions of the adult. They are nocturnal predators of small invertebrates and scavenger feeders. Feeding is helped by their ability. to tie themselves in a knot, and they use this as a form of leverage to tear off flesh. The jawless but biting mouth is surrounded by six barbels. A terminal nostril detects dead or dying prey.
Chondrichthyes: Cartilaginous fishes that include sharks, rays and chimaeras. There are thought to be 415 species of sharks, 547 species of rays and 37 species of chimaeras. The largest fishes in the world are the plankton-eating whale shark (>12 m) and basking shark (9 m). There are also large carnivorous sharks, well known to humans, such as the white, tiger, hammerhead and thresher (5-6 m). On the other end of the scale, deep-water dogfishes grow to less than 8 inches (20 cm). Rays can also achieve great size-manta rays can grow to a width of 7 m. Most sharks and rays are entirely marine but 28 species are found in freshwater. Although often portrayed as primitive, modern sharks and rays are highly specialized fishes and quite different from their early ancestors. The chimaeras are entirely marine and reach a maximum length of about 1.5 m.
Reproduction: All living sharks, rays and chimaeras have internal fertilization and produce large, yolky eggs in relatively small numbers. This makes them highly susceptible to over-exploitation. Males do not have a true penis, but have modified pelvic fins known as claspers to help the transfer of sperm; chimeras also have an additional clasper on their heads. Females either lay eggs in tough leathery pouches or nourish embryos internally for several months before giving birth. Gestation can be extremely long. The spiny dogfish has a gestation period of two years, while the basking shark's may be more than three years. These fishes have a range of reproductive strategies, varying from simple egg laying (oviparity) to advanced live bearing (viviparity), where the young are nourished via a placenta similar to that of mammals.
Bony Fishes: The most abundant and species-rich group of all the vertebrates. Unlike the sharks and rays, they have skeletons made of bone. Most living species of bony fishes belong to the ray-finned fishes (Actinopterygii) because the fins have fin rays that are soft and often branched. The ray-finned fishes can be further divided, depending on the presence of spines, into the soft-rayed and spiny-rayed fishes. There are four main groups of living soft-rayed fishes, three of which are marine. These are the bonytongues and relatives (freshwater), the eels and tarpons, the herrings and a number of sub-groups that include catfishes. There are at least 24,600 species of ray-finned fishes, of which 11,345 have soft fin rays and the remainder have spines as well as soft fin rays. The internal anatomy of the soft-rayed fishes differs in two main respects from that of spiny-rayed fishes. Firstly, where it is present, the gas bladder in soft-rayed fishes remains connected to the esophagus and gas can be lost or gained by swallowing air or releasing gases via the mouth. There is also gas secretion and reabsorption via the gas gland that is attached to the gas bladder. Soft-rayed fishes also differ from spiny-rayed species in having a separate pancreas and liver.
Spiny-Rayed Fishes: Most of the fish species living today belong to the 13,262 species of spiny-rayed fishes, of which 10,177 are marine. The marine forms can be divided into three main types: the mullets, the sand smelts and their relatives, and the perches and perch-like fishes. As their name implies, the unique characteristic of this group of fishes is that, in addition to soft fin rays to support their fins, they also have sharp spines in their dorsal, pelvic and anal fins. The spiny-rayed fishes are found in all marine habitats and have evolved a huge variety of lifestyles, often modifying their major body structures, such as their complex jaws. Most spiny-rayed fishes have a gas bladder that is sealed, so buoyancy is regulated solely by secretion or absorption of gases via the gas gland. Some species, such as some tunas, move rapidly through large vertical distances and avoid the difficulty of regulating their gas bladders by dispensing with them entirely. Spiny-rayed fishes have a combined pancreas and liver called a hepatopancreas.
Marine Reptiles: Although reptiles are the most ancient, truly terrestrial vertebrates, they have also evolved marine species several times during their 300My history.
Turtles: The oldest group of living reptiles in the sea, though there are only eight truly marine species left. Sea turtles spend most of their lives in the water, coming ashore only to lay eggs.
Sea Snakes: Relatively recent returnees to the sea but, nevertheless, they are the most abundant living marine reptiles, both in terms of numbers and variety of species. Although they are all highly venomous carnivores, related to cobras, sea snakes are not aggressive to humans. The size of their mouths, in which the fangs are placed to the rear, makes it difficult to be bitten.
Lizards & Crocodiles: Represented by only two species, the marine iguanas and the saltwater crocodiles. The main natural limitation on the distribution of reptiles is water temperature; they are cold blooded and cannot survive for any length of time in cold water.
Dugongs (Sea Cows) & Manatees: Marine mammals that share an ancestor with elephants. They grow up to 3 m long and weigh up to 400 kg. The largest dugong, Steller's sea cow, weighed as much as 5 tons (5.5 t); it was hunted to extinction in the 18c. The dugong has a rounded body with forelimbs modified into flippers and rear legs fused into a single tail fluke. Its thick skin, beneath which is a thick layer of blubber, has some hair covering. Dugongs are slow, placid animals that live on eel and turtle grasses in shallow tropical waters. They spend their lives in the water, even giving birth there. One puzzling feature of dugong biology is that they have solid bones with no marrow, and it is not known where they manufacture their red blood cells. Manatees are relatives of the sea cow. They are found mainly in estuaries and in the lower reaches of rivers. Manatees are more social animals than dugongs, congregating in large groups to rest during the day and dispersing to feed at night.
Whales, Dolphins & Porpoises: The largest group of marine mammals; they have a completely aquatic lifestyle. There is some dispute as to the exact number of species, but it is estimated there are between 79-90. These fall into two groups: baleen whales, which are filter feeders; and the toothed carnivorous species, which include the smaller whales and all dolphins and porpoises. With the exception of five species of freshwater dolphins, they are all exclusively marine. All whales, dolphins and porpoises have a hairless, streamlined body with flipper forelimbs and a huge horizontally fluked tail to propel them through the water. One of the paradoxes of whale biology is that the largest whales eat the smallest food. The largest animals that have ever lived on Earth are blue whales that can reach 33.5 m in length and weigh 196 tons (178 t), yet they feed only on large zooplankton, such as krill. These filter feeders, or baleen whales, get their name from the hairy plates that hang down from the roofs of their mouths and strain huge volumes of water in each gulp.
Pinnipeds: Marine mammals that include seals, sealions and walruses. They evolved from land carnivores and have become superbly adapted to life in water. Nearly all species are marine, but there are isolated freshwater populations of seals. Although clumsy and ungainly when they haul out, in the water pinnipeds are graceful, agile swimmers. The most obvious adaptations to life in water are their rounded bodies and the modification of their limbs into flippers. Many other adaptations enable them to live in the oceans at all latitudes. Fur and thick blubber insulate them against the cold, their eyes can focus in water, and whiskers acting as feelers supplement their underwater vision. These mammals have a large blood volume and blood chemistry adapted to diving. As a result, they can regularly dive for 20-30 min down to 100m. The deepest divers are the Weddell seals that are known to dive to nearly 300 m and remain submerged for 45 min. Seals, sealions and walruses have few natural predators, the main ones being leopard seals, large sharks and killer whales. However, hunting, drowning in nets and shooting by fishermen have brought many species to the brink of extinction.
Seabirds: ~3% of the estimated 8600 known bird species are described as seabirds, and they are found from pole to pole. They are a major component in many marine ecosystems. Seabirds developed from several different groups of land birds, so have widely differing styles of feeding and flight, and endurance capabilities at sea. However, they have common characteristics that define them as seabirds: they rest ashore and return to the land to lay eggs; they have webbed feet used for landing on water and swimming; and they feed on fishes, squid, bottom invertebrates and plankton. All are voracious feeders, as flying and swimming expend a great deal of energy. Seabirds are divided into five groups: penguins, tubenoses, pelicans and cormorants, gulls and terns, and shore birds.
Sea Adaptations: Penguins are the most highly adapted seabirds. They have lost the power of aerial flight but effectively fly underwater at high speed, using wings modified into flippers. Thick layers of feathers and body fat insulate them against heat loss in cold water. The tubenoses-albatrosses, shearwaters and petrels-get their name from their distinctive nostrils that contain glands that secrete excess salt, allowing them to drink seawater and remain at sea for long periods. Tubenoses have light bones and, therefore, a light body for their size. Because of their weight, they are able to glide easily. Pelicans, cormorants and frigate birds have strengthened wings and necks so that they can plunge dive or maximize the number of fishes they can carry back from each feeding trip. Shore birds have long legs, light bodies and probing, sensitive bills.
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Into the Deep
Deep Sea Worms: Range in size from the microscopic to 2 m long and are one of the most abundant and diverse groups of invertebrates living in the deep sea. Most worms live buried, or partially buried, in the soft sediments that cover the majority of the deep seafloor.
Segmented (polychaete) Worms: Small, but numerous, both in terms of individual numbers and numbers of species. Most polychaete worms feed on organic particles captured with elaborate tentacles, or extracted from the mud as they browse through it. A small number live in, or on, larger animals such as sea cucumbers.
Vent Tube Worms: Relatives of the polychaetes; they are much larger and have developed specialized feeding mechanisms to use the chemical energy in hydrothermal vents.
Peanut (sipunculans) & Spoon (echiurans) Worms: Some of the biggest worms found in the deep sea. They are important in breaking down larger pieces of organic material on the seafloor.
Non-parasitic Thread Worms (Nematodes): The most abundant group of worms; there are thought to be between 10-100M species of nematodes in the oceans. Although <1 mm long, they can represent 50-90% of the live weight of animals in deep sea sediments. The diversity of the nematode species means that a sediment sample in one area will be completely different from a sample in an area <1 km away.
Deep Sea Cucumbers (Holothurians): One of the most abundant groups of megafaunal animals those that are larger than 2.5 mm-living on the deep seafloor. It is estimated that they form ~95% of the total biomass (the weight of live animals) over large parts of the deep seafloor. Their relative abundance increases with depth. At hadal depths in trench systems, such as the Kuril-Kamchatka Trench, they form 98% of all the individuals in trawl samples. Deep sea cucumbers are nearly all surface feeders, continually moving over the soft mud of the deep seafloor, ingesting the veneer of fine particles that have settled out from the water. Some species have been observed in large "herds" and have been likened to bison grazing over the prairies. Not all holothurians are slow-moving surface feeders. Some bury themselves with just the ends of their bodies at the surface, and others live buried headfirst in the mud. A small number, however, have become buoyant and are able to swim off the bottom.
Deep Sea Adaptations
Eyesight: Many animals have evolved extremely complex and highly sensitive eyes. These help to discern the faintest glimmer of surface light and occasional flashes of bioluminescence.
Smell: Many deep-sea animals have highly developed olfactory senses for detecting food or mates in the deserted expanse of the deep sea. They can detect chemicals leaching from food items or pheromones from potential mates.
Sound: In the deep-sea, water is a far better transmitter of low-frequency pressure waves than air. What we regard as the sense of hearing is, in many deep-sea animals, a long-distance sense of touch-they detect vibrations from other animals in the deep.
Touch: Many invertebrates hear/touch using sensitive hairs or antennae, and in fishes the "lateral-line" system functions like our inner ear-sensitive hairs transform microscopic movements into nerve impulses.
Hearing: Many fishes produce sound so they must also possess a sense of hearing as we understand it.
Gravity: Most active deep-sea animals are able to detect gravity. Invertebrates have simple receptors called statocysts, but fishes have more elaborate semicircular canals. These not only provide information on vertical orientation but can also assess changes in speed.
Bioluminescence: Organisms that produce light without heat by the action of the enzyme luciferase on the substance luciferin in the presence of O. In the deep sea, bioluminescence is used by animals to provide counter-illumination to break up their silhouette, to lure prey, to distract predators and to signal other members of their own species. Some fish species are able to produce red light. This is invisible to most deep-sea species and enables the predator to illuminate potential prey without alerting them to their presence. In animals such as jellyfishes and comb jellies, light is produced in individual cells spread over the animal's surface. In most cases, however, light is produced by specialized and often complex organs called photophores. In some species, the luciferase and luciferin are manufactured by the animal itself. In others, the photophore contains bioluminescent symbiotic bacteria nourished by the host. Photophores are used to control the color, intensity, direction and flashing rate of the emitted light. However, not all bioluminescence is confined to cells or photophores. Many species have not only photophores, but also specialized glands to squirt out bioluminescent fluids to confuse and divert predators.
Eating: Animals of the deep sea live in a vast, sparsely populated environment where encounters with other creatures are infrequent. The difficulties this presents in terms of feeding are overcome by mechanisms that ensure a wide range of food sizes and types can be eaten.
Sex: Deep sea animals have evolved a number of strategies to attract members of the opposite sex, including signaling and attractants, such as sound production, bioluminescent patterns and chemicals known as pheromones, increase the possibility of such encounters. The chances of a fruitful encounter are also enhanced by hermaphrodite individuals or by the forming of long-term pair bonds. This is taken to an extreme form in some anglerfish species. Successful reproduction depends not only on getting parents together, but also on the biology of the offspring. When conditions are stable for long periods, the animals in the lower layers of the deep sea take the risk of investing in a small number of large, yolky eggs. These eggs have a very short larval stage and most of the offspring will survive. In contrast, species in shallow water produce large numbers of small eggs, most of which die.
Cold Seep: Occurs around all types of continental margin, in areas where methane and sulfide-rich fluids seep through the deep ocean floor. Although similar in many ways to hydrothermal vents, they are distinct—cold seeps release their cargo of chemicals at the same temperature as the surrounding water. Most cold seeps have been discovered when submersibles have come across pockmarks, or mud volcanoes, with communities of animals like those around hydrothermal vents. This similarity is no coincidence. Similar to the animals around hydrothermal vents, cold seep animals are dependent on symbiotic bacteria for their survival-the bacteria converts the methane and hydrogen sulfide into food for the seep community.
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The Fringes
Coral Reefs: A maritime ecosystem that begin growing in the world's oceans more than 450 Ma. They form massive structures that are not only fascinating biological communities, but also the largest geological structures on the planet that are formed by living organisms. With the exception of one or two cold-water species, the reef-building, or hermatypic, corals are extremely temperature sensitive. They can grow only where the water temperature does not fall below 21°C or rise significantly higher. As a consequence, coral reefs are restricted to tropical waters (~30°S to 32°N) and are not found on the westward-facing coasts of landmasses. These are areas of upwelling that bring cold, deep water to the surface, lowering the water temperature. Reefs are classified as fringing, barrier, and atolls.
Fringing Reef: Form in direct contact with the margins of the land, usually on the downwind (low rainfall) margins of tropical islands.
Barrier Reefs: Separated from the shore by a lagoon or channel and are found around islands or parallel to continental coastlines.
Atolls: Ring-shaped coral islands circling a shallow lagoon. Some 300 atolls have been charted throughout the world, the majority of which are in the Pacific.
Coral Bleaching: Occurs when affected corals expel the zooxanthellae (symbiotic algae) that give them much of their color, resulting in white patches over the colony. Bleached colonies never lose all their zooxanthellae. In some cases, there is a degree of recovery where new species of zooxanthellae become viable within the coral polyps. However, bleached colonies do not continue to grow and are more susceptible to being broken apart by wave action.
Shelf Seas: The shallow-water zones around continental margins, which are the oceans' major source of biological and mineral riches. Some 90% of all commercially exploited fish species consumed in Europe and North America, come from shelf-sea fishing grounds. They extend from the low water mark to the edge of the shelf break. The average width of the continental shelf is 70 km but it can be much wider. There are two types of continental margin- Atlantic and Pacific.
Atlantic Continental Shelf: A shelf that is broad, stable and gently sloping.
Pacific Continental Shelf: A shelf that is narrow and often close to areas of seismic activity.
Estuaries: Ecosystems where the sea not only meets the land but also mixes with freshwater, giving rise to environments that have a highly specialized set of plants and animals. Many of the world's great cities, such as London, Tokyo and New York, are sited on estuaries. Estuaries are formed in four ways, and can also be classified according to levels and interaction between fresh and saltwater.
Drowned River Valley Estuary: Form when existing river valleys are flooded by seawater, and sedimentations rates do not keep up with rising sea levels. They retain a V-shaped cross-section. They often have extensive mudflats.
Tectonic Estuary: The rarest of the main estuary types. They form when local faulting and subsidence cause the inundation of land below sea level by fresh and saltwater (i.e., San Francisco Bay).
Fjords: Formed ~18 Ka, at the beginning of the last ice age. Fjords are deep and sheer-sided, as the flow of ice down pre-existing river valleys deepened and widened them. In most fjords, the river flow is small, with little settlement.
Bar-Built Estuary: Beginning as drowned river valleys, here the sediment keeps pace with sea levels. These estuaries occur where there is a large river flow and sediment burden, which increases in periods of flood. This sediment results in the creation of a bar and lagoon.
Mangroves: A habitat type composed of a wide variety of mangrove trees, ranging from small shrubs to large trees. They are adapted to living in soft, waterlogged, often anoxic (O-poor) mud, as well as a daily inundation of saltwater. Mangroves share one overriding characteristic-mangrove trees and shrubs cannot survive temperatures that fall more than 10°C below their ideal of 19°C. As a consequence, they are restricted to the climates of tropical and subtropical estuaries where they can be found on both the westward- and eastward-facing coasts. Mangroves form spatially complex 3D habitats with an extremely varied set of animal populations, each exploiting different aspects of mangrove ecology.
As mangroves grow in extent, there is a gradual increase in the stability of the sediments on the landward side. In the oldest part of the mangrove, the mud is solid enough for burrowing species such as fiddler crabs and mud lobsters to dig permanent holes. On the firmest mud, animals such as crocodiles are able to move onto land, and the larger land animals can also feed on the margins. Moving toward the seaward fringe of the mangrove, the mud becomes softer and only animals that can cope with such conditions can flourish here. For example, the tropical cockle has ribs and spines that stop it sinking into the soft sediment, and the window oyster has a large, very thin shell that spreads its weight like a snowshoe across the mud.
Kelps: A form of algae that grow as forests in cold, nutrient-rich water. They are found mainly in the higher, temperate latitudes on the western sides of continents, where upwelling and current systems convey this type of water. Most kelp forests tend to be situated some distance offshore and can be as deep as 40 m. Both these features of their location help the kelp to avoid excessive shearing forces caused by wave action. Kelp forests are similar to their terrestrial counterparts in that they have a complex 3D structure. Beneath a wide canopy of kelp lies a dense understory of smaller seaweeds that have adapted to low light levels. Many different animals shelter between the fronds or firmly attach themselves to the kelp itself.
Sea Grasses: Flowering plants with roots, leaves and stems that distribute their pollen in seawater currents rather than by air or via insects. They are found throughout the coastal margins of temperate and tropical zones and are probably some of the most productive habitats on Earth, producing about 3½ ounces of new plant tissue per square foot each year. There are ~50 species of sea grasses and all are found on mud, or muddy sands, from the low watermark downward, often forming luxuriant beds or meadows. The maximum depth at which they can grow is determined by the clarity of the overlying water. Both sea-grass beds as a whole and individual plants within them are important marine habitats.
Eel Grasses: The principal sea-grass species in temperate zones. They are sometimes found exposed on the lower shore but can grow as deep as 30 m.
Turtle & Manatee Grasses: The principal sea grasses in tropical and subtropical areas. They are found from the edge of the shore down to 10 m, depending on conditions.
Strandline: The shoreline marking the last high tide.
Muds (in estuaries): Favored by animals, such as the polychaete worms, that use them to avoid the rapid changes of salinity in the overlying water. Water penetrates slowly into mud; salinity changes are, therefore, slow and greatly reduced in range. However, mud dwellers have to overcome considerable problems. First, in addition to inorganic particles, large amounts of organic matter are deposited at the same time, which will decay and use up oxygen. Secondly, oxygenated water cannot penetrate more than ~2.5 cm into muds. The combination of these factors means that only the top layers of the mud contain oxygen. Sediments below the top quickly become more anoxic with depth. The lack of oxygen allows the growth of bacteria, which produces hydrogen sulfide. This poisonous chemical reacts with iron salts, turns the mud black, and gives it an unpleasant rotten-egg smell. Animals are able to live in mud either by maintaining contact with the surface or by adapting to life with little or no oxygen. Some even make use of the hydrogen sulfide, in the same way as deep-sea vent animals.
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The Human Impact
Commercial Fishing: A large-scale industrial process that employs increasingly efficient means of removing animals, mainly fish, from the sea. Processes include: purse seining, trawling, gill netting and long-lining.
Purse-Seine Netting: Uses a long net drawn around surface-living fishes such as tuna, sardines and herring. When the ends of the net are brought together, and the bottom hauled in, whole shoals of fishes are caught.
Trawling: Uses a huge baglike net drawn over the bottom to catch bottom-living species such as flatfishes. To protect the mouth of the net, and to force fishes to swim off the bottom and into the oncoming net, trawls have heavy chains at the front that churn up the seabed.
Gill Nets: Use vertically hung nets, like an invisible mesh curtain in the water, to catch midwater fishes and are often 20 km long.
Longlines: Lines of baited hooks that are used in some areas to catch squid and tuna. They are seen as a less-damaging alternative to gill nets.
Overfishing: At least 20 of the world's most important fisheries have disappeared since the mid-1970s, and many more have been so badly affected by overfishing that they are unlikely to recover. One of the best-known examples was the total collapse of the Grand Banks cod fishery in the northwest Atlantic in the early 1990s. A once-abundant cod stock became uneconomic to fish and stocks have not yet shown any signs of recovery. The problem of overfishing has been created by the doubling of the global demand for fishes and other marine animals over the last 30 years. This is the result of population growth in the developing countries and the need for cheap sources of protein. The only way wild stocks will survive as a viable and renewable resource will be to ensure that only a sustainable yield is taken. International controls need to regulate mesh sizes to ensure undersized fishes are not caught, and quotas should leave enough adults to breed, as well as leaving food for other marine animals.
Pollution: The introduction of substances, material or unwanted heat energy from human activities, that adversely affect an ecosystem.
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Terminology
Benthic: The seafloor.
Blue Desert: An area of the ocean with minimal primary production throughout the year.
Blue Riband: A hypothetical honor awarded to a ship making the fastest transatlantic crossing between the lights off the Scilly Isles and the entrance to NY harbor. The last liner to hold the honor was the United States, which made the crossing in 1952 in 3 days, 10 hours, and 31 minutes.
Pelagic: Water column.
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Chronology
50 My: The Mediterranean disappears as Africa and Europe join (Oceans by Hutchinson).
2000: The International Hydrographic Organization formally recognizes the Southern Ocean (Oceans by Hutchinson).
1995: The Osprey is launched as the world's first commercial offshore wave-energy generator, producing 2 MW of electricity (Oceans by Hutchinson).
1985: US Oceanographer Robert Ballard discovers the Titanic using his ROV Argo (Oceans by Hutchinson).
1985: Whaling is banned worldwide, although Japan, Iceland, and Norway continue to hunt smaller whales under the guise of “scientific whaling” (Oceans by Hutchinson).
1978: Launch of SEASAT- the first satellite dedicated to oceanographic measurement (Oceans by Hutchinson).
1978: Launch of GPS, operated by the US to give continuous worldwide coverage (Oceans by Hutchinson).
1977: The submersible Alvin discovers hydrothermal vents and the animal life they support around the Galapagos identifying that animals can be sustained by chemical energy rather than sunlight (Oceans by Hutchinson).
1975: The Regional Seas program begins to clean up the Mediterranean (Oceans by Hutchinson).
1975: The Great Barrier Reef is protected as a World Heritage site (Oceans by Hutchinson).
1970: The National Oceanic and Atmospheric Administration (NOAA) is set up in the USA (Oceans by Hutchinson).
1967: The first large-scale tidal power station is completed on the Rance River in France which flows into the Gulf of Saint-Malo, Brittany. The station spans the estuary and has 24 power units of 10kW each (Oceans by Hutchinson).
1965: The International Whaling Commission introduces protection for the blue, gray, and humpback whales (Oceans by Hutchinson).
1960: Harry Hess and Robert Dietz propose that the ocean basins are formed by spreading from the mid-ocean ridges and that crustal material is lost at ocean-margin subduction zones (Oceans by Hutchinson).
1959: The Soviet icebreaker ‘Lenin’ and the US Merchant Ship ‘Savannah’ are commissioned as the first nuclear powered surface ships (Oceans by Hutchinson).
1958: The submarine USS Nautilus surfaces through ice at the North Pole proving there was no Arctic continent hidden beneath the ice (Oceans by Hutchinson).
1955: The USS Nautilus is launched as the first nuclear powered submarine (Oceans by Hutchinson).
1950: Commencement of the Danish Galathea expedition to explore life in the deep ocean (Oceans by Hutchinson).
1943: French Naval Lieutenant Jacques-Yves Cousteau (1910-1997) and gas engineer, Emile Gagnan, develop the aqualung, with a max depth of 61m (Oceans by Hutchinson).
1934: Scientific exploration of the ocean depths begins after Americans William Beebe and Otis Barton descend to 922m in a bathyscaphe- a hollow steel sphere suspended form the surface by a thin cable that carried a telephone line and power for a single electric bulb (Oceans by Hutchinson).
1933: Frenchman Louis de Corlieu patents rubber fins for underwater swimming (Oceans by Hutchinson).
1925: Launch of the US Meteor expedition, which uses the first echo sounder to map the seafloor (Oceans by Hutchinson).
1924: Nitrogen Narcosis (‘rapture of the deep’) leads to the first experimental He-O dives in trials conducted by the US Navy and Bureau of Mines (Oceans by Hutchinson).
1913: The first tidal power station is built on the Dee estuary in England (Oceans by Hutchinson).
1912: The RMS Titanic strikes in iceberg in the North Atlantic on its maiden voyage, resulting in the loss of 1503 lives (Oceans by Hutchinson).
1911: Norwegian Roald Amundsen reaches the South Pole (Oceans by Hutchinson).
1910: Selandia, a Danish merchant ship, becomes the first ocean-going, diesel powered ship (Oceans by Hutchinson).
1909: Australian Douglas Mawson reaches the South magnetic pole (Oceans by Hutchinson).
1902: The ‘Petit Pierre’ is launched as the first diesel powered boat in France (Oceans by Hutchinson).
1900: Italian engineer Enrico Forlanini (1848-1930) builds the first hydrofoil (Oceans by Hutchinson).
1899: Carsten Borchgrevink leads a British expedition that lands at Cape Adare, believed to be the first confirmed landing on Antarctica (Oceans by Hutchinson).
1897: Irish-American John Phillip Holland (1840-1914) designs the Holland IV- the prototype of the modern submarine- combining the internal combustion engine for surface use and charging lead-acid accumulators that power an electric motor when underwater (Oceans by Hutchinson).
1888: The Marine Biological Lab is founded at Woods Hole, Massachusetts, USA (Oceans by Hutchinson).
1886: The first boat powered by an internal combustion engine is built by Gottlieb Daimler (Oceans by Hutchinson).
1884: The Marine Biological Association of the UK is founded (Oceans by Hutchinson).
1880: Englishmen Reverend George Garrett successfully demonstrates a steam-driven submarine, the Resurgam. Steam was first generated in a coal-fired boiler on the surface. The craft then retained sufficient heat to drive underwater for some time (Oceans by Hutchinson).
1876: Englishmen Henry Fleuss develops the earliest self-contained breathing apparatus with a max depth of 18m (Oceans by Hutchinson).
1872: The first global oceanographic expedition commences aboard the HMS Challenger (Oceans by Hutchinson).
1865: Rouquayrol and Denayrouze develop the demand valve, which allows surface air to be used by a diver to a max depth of 30m (Oceans by Hutchinson).
1864: The CSS Hunley sinks the USS Housatonic in Charleston Harbor; the first warship sunk by a submarine (Oceans by Hutchinson).
1859: The Great Eastern is launched; designed by Isambard Kingdom Brunel (1806-1859), the ship combined paddlewheels with screw propulsion and remained the largest ship built for the next 50 years (Oceans by Hutchinson).
1855: Matthew Maury (1806-1873) publishes the Physical Geography of the Seas- the first comprehensive work on physical oceanography (Oceans by Hutchinson).
1855: German Wilhelm Bauer builds the submarine Le Diable-Marin for the Russian Navy. It is hand-cranked and makes 134 dives before sinking (Oceans by Hutchinson).
1838: The Great Western, designed by British engineer Isambard Kingdom Brunel (1806-1859), begins the first regular steamship crossings of the Atlantic (Oceans by Hutchinson).
1835: Gaspard Coriolis publishes his treatise on the influence of Earth’s rotation on moving objects, leading to an understanding of winds and currents (Oceans by Hutchinson).
1828: Deane develops the earliest diving helmet, with a max depth of 24m (Oceans by Hutchinson).
1821: American sealer Captain John Davis makes the first landing on continental Antarctica (disputed) (Oceans by Hutchinson).
1819: The Savannah makes the first steam crossing of the Atlantic (Oceans by Hutchinson).
1819-1821: Russian navigator Fabian von Bellingshausen circumnavigates the Antarctic and discovers some offshore islands (Oceans by Hutchinson).
1802: Scottish Engineer William Symington (1763-1831) launches the Charlotte Dundas, the first stern paddle-wheel steamboat (Oceans by Hutchinson).
1786: French naval officer Jean-Francois La Perouse (1741-1788) maps the west coast of North America (Oceans by Hutchinson).
1783: Jouffroy d’Abbans (1751-1832) builds the first paddle-driven steamboat in France (Oceans by Hutchinson).
1777: The first iron-hulled boat is built in Yorkshire, England (Oceans by Hutchinson).
1772-1773: Englishman James Cook’s (1728-1779) second voyage takes him to Antarctica and Easter Island (Oceans by Hutchinson).
1769: Benjamin Franklin (1706-1790) publishes the first chart to show an ocean current (the gulf stream) (Oceans by Hutchinson).
1768: Englishman James Cook (1728-1779) makes a scientific voyage to Tahiti that includes mapping the coast of N. Australia (Oceans by Hutchinson).
1730: John Hadley (1682-1744) develops the modern sextant (Oceans by Hutchinson).
1725: Danish explorer Vitus Bering (1681-1741) begins explorations of the seas off Alaska and NE Siberia and discovers a sea route around Siberia to China (Oceans by Hutchinson).
1715: Lethbridge develops the armored diving suit, which is capable of descending to 22m (Oceans by Hutchinson).
1714: The Board of Longitude is set up in England. It offers a 20,000-pound prize to anyone with a practical means of determining longitude at sea. The self-taught English clockmaker John Harrison (1693-1776) spends the next 50 years developing an accurate chronometer in order to claim the prize (Oceans by Hutchinson).
1707: The loss of four English warships and the deaths of 2000 men, including Admiral Sir Cloudsley Shovell (1650-1707), wrecked on the Scilly Isles is attributed to inaccuracies in determining longitude (Oceans by Hutchinson).
1690: Edmund Halley (1656-1742) develops the earliest diving bell, which is capable of descending to 18m (Oceans by Hutchinson).
1675: English King Charles II (1630-1685) establishes the Royal Observatory at Greenwich to produce astronomical tables for navigation, particularly to solve the problem of determining longitude at sea (Oceans by Hutchinson).
1667: Robert Boyle (1627-1691) records observations of decompression sickness (DCS) or ‘the bends’ when he observes gas bubbles in the eye of a viper that had been compressed and then decompressed (Oceans by Hutchinson).
1642: Abel Tasman (1603-1659) becomes the first European to sail to Tasmania, New Zealand, Tonga, and the Fiji Islands (Oceans by Hutchinson).
1628: The Swedish warship Vasa sinks on her maiden voyage in Stockholm. She is later found and raised in 1961 (Oceans by Hutchinson).
1620: Dutchman Cornelius Drebbel demonstrates his 12-oared, wood, and leather submarine to English King James I. The boat uses tubes attached to floats to carry air from the surface (Oceans by Hutchinson).
1616: Dutchman Dirck Hartog (1580-unk) charts the West coast of Australia (Oceans by Hutchinson).
1610: Englishman Henry Hudson (1565-1611) explores part of the Arctic Ocean and Hudson Bay (Oceans by Hutchinson).
1606: Dutchmen Willem Jantszoon (1571-1638) becomes the first European to sail to Australia (Oceans by Hutchinson).
1537: Flemish mapmaker Geradus Mercator (1518-1594) designs the ‘Mercator Map’ specifically for navigation. The Mercator map was the first successful means of representing a spherical shape of Earth on a flat map, rather than a globe (Oceans by Hutchinson).
1526: Sebastian Cabot (1474-1557), a Venetian-born navigator and cartographer to Henry VIII of England, begins exploring the Brazilian coast (Oceans by Hutchinson).
1522: Portuguese navigator Ferdinand Magellan (1480-1521) completes the first circumnavigation of the world and names the Pacific Ocean (Oceans by Hutchinson).
1497: Portuguese navigator Vasco de Gama (1460-1542) reaches India by sea from Portugal (Oceans by Hutchinson).
1492: Genoese-born Christopher Columbus (1451-1506) makes the first voyage to the Americas under the patronage of King Ferdinand and Queen Isabella of Spain (Oceans by Hutchinson).
1488: Portuguese Navigator Bartolomeu Dias (1457-1500) rounds the Cape of Good Hope (Oceans by Hutchinson).
1419: Prince Henry of Portugal (1394-1460) sets up the first school for navigators (Oceans by Hutchinson).
1405-1433: The Chinese explore the Indian Ocean around the Cape of Good Hope (Oceans by Hutchinson).
1400-1500: Three masted ships with large hulls for cargo and supplies are developed in NW Europe (Oceans by Hutchinson).
~1000: Lief Eriksson reaches North America via Greenland (Oceans by Hutchinson).
1000: Eric the Red reaches Greenland from Iceland (Oceans by Hutchinson).
850: Polynesians reach New Zealand (Oceans by Hutchinson).
500: Polynesians cross the Pacific to colonize Hawaii (Oceans by Hutchinson).
200-300: Arabs and Romans develop fore and aft rigging to allow boats to sail across the wind (Oceans by Hutchinson).
200: The Chinese build the first multi-masted ships (Oceans by Hutchinson).
100: The Chinese invent the rudder, making the development of large ocean-going vessels possible (Oceans by Hutchinson).
127 BCE: Hipparchus (190-120 BCE) creates a regular grid of latitude and longitude to improve navigation (Oceans by Hutchinson).
200 BCE: Invention of the astrolabe, a tool used to measure the angle between the sun, horizon, and principal stars (Oceans by Hutchinson).
230 BCE: Eratosthenes makes the first estimate of Earth’s circumference and invents the concept of latitude and longitude (Oceans by Hutchinson).
300 BCE: The Chinese invent the compass, enabling them to voyage out of sight of land and at night (Oceans by Hutchinson).
325 BCE: The Greek navigator Pytheas sails to Britain and links lunar movements to the rise and fall of the tide (Oceans by Hutchinson).
1000 BCE: Polynesians reach Tonga and Samoa (Oceans by Hutchinson).
1200 BCE: The Phoenicians establish maritime trade in the Mediterranean, the British Isles, and W. Africa in keeled boats with hulls built of planks. Boats carry tin, gold, spices, and gemstones (Oceans by Hutchinson).
2300 BCE: The first documented explorer, Egyptian noblemen Harkuf, leads expeditions up the Nile to the land of Yam (southern Nubia) (Oceans by Hutchinson).
2750 BCE: The first recorded expedition of marine exploration occurs in Egypt (Oceans by Hutchinson).
15 Ma: The oceans arrive at approximately their present form (Oceans by Hutchinson).
95 Ma: The South Atlantic basin begins to develop and joins the North Atlantic, in the process shrinking Panthalassia into part of the Pacific Ocean (Oceans by Hutchinson).
130 Ma: A semi-enclosed sea, the Sinus Borealis, on the Northern edge of Pangea begins to widen into the Arctic Ocean (Oceans by Hutchinson).
140 Ma: Gondwana breaks apart into the Indian, African, and Antarctic landmasses and forming the Indian Ocean (Oceans by Hutchinson).
150 Ma: Pangea breaks up forming Gondwana and Laurasia, which opens up the North Atlantic that begins widening at a rate of ~2.5cm per year because of seafloor spreading at the Mid-oceanic ridge (Oceans by Hutchinson).
200 Ma: Earth has one superocean, Panthalassia, surrounding a single supercontinent, Pangea, and a sea, the Tethys Sea (later the Mediterranean) (Oceans by Hutchinson).
200 Ma: Evolution of Turtles (Oceans by Hutchinson).
450 Ma: Coral Reefs begin growing in the world’s oceans (Oceans by Hutchinson).
4.3 Ga: Earth experiences 10M years of intense rainfalls that cool the Earth and wash minerals from the hot rocks into the oceans. As a result, the oceans that form are a complex solution of salts (Oceans by Hutchinson).
4.6 Ga: Formation of the Earth (Oceans by Hutchinson).
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