Welcome to CoveBear.com! - Oceans of the World

An ocean is a large body of water that is 3.5% salt. Although there is really only one ocean on Earth, we divide that ocean into areas called the five oceans of the world, so that we can easily identify them. All of our oceans are connected. The five oceans of the world cover 71% of the earth's surface, and contain 97% of the Earth's water. The five oceans of Earth are all connected and flow into each other. The oceans are divided by land masses such as continents, archipelagos, and islands. The bottom of oceans is made up of material deposited there by volcanic eruptions, and is a sandy crust. Oceans are very deep and have many kinds of animals and plants living in them. Since there is life there, oceans are called ecosystems in a broader sense, and habitats in a localized sense.

Oceans are made up of smaller bodies of water we call seas. Most salty water is away from land masses, although there are exceptions to this rule: the Aral Sea and the Great Salt Lake were once seas and are now salty lakes contained within a land mass.

Most of the Earth's weather and climate is created by the oceans, and there are many storms occurring over oceans. Ocean waters move in currents that may go north and south or east and west. Some of these moving water currents are warm and others are cold. Generally warm currents will flow on top of the oceans going one way, curve down and move colder currents underneath the surface back the other way. The currents that bring ocean water up onto a beach, and then cause it to recede again, are called tides. Oceans also are mostly responsible for the shape of our coastlines.

50% of all species on Earth live in the ocean.

WHAT IS THE DIFFERENCE BETWEEN A SEA AND AN OCEAN?

An ocean is very large and is out in the open. An ocean is deeper, has larger waves, and more weather. A sea is a smaller body of water, partially enclosed by land. The three largest seas in the world are the South China Sea, the Caribbean Sea, and the Mediterranean Sea. The other seas are: Bering Sea, Gulf of Mexico, Arabian Sea, Sea of Othotsk, Sea of Japan, Hudson Bay, East China Sea, Andaman Sea, Black Sea, and Red Sea.

In this true photo by NASA, you can clearly see

how much of the Earth is water,

as it is seen here with North America. The blue is water,

the white is cloud cover, the brown is land mass.

Reprinted with permission to CoveBear.

WHERE ARE THE FIVE OCEANS AND HOW BIG ARE THEY?

LARGEST OCEAN AND LARGEST FEATURE OF THE EARTH - THE PACIFIC OCEAN: The Pacific Ocean is located between Asia and North America and between Australia and South America. It's size is huge at 64 million square miles, or about 1/3 of the earth's surface. The deepest part of the Pacific Ocean is the Marianas Trench located near the Northern Marianas Islands. There the ocean is 35,838 feet deep. SECOND LARGEST OCEAN - THE ATLANTIC OCEAN: The Atlantic Ocean is located between Europe / North America and between Africa / South America. It is 32 million square miles. Its deepest area is at the Puerto Rico Trench, which is 28, 231 feet deep. THIRD LARGEST OCEAN - THE INDIAN OCEAN: The Indian Ocean is located south of Asia (India), west of Australia, and east of Africa. It is 28 million square miles in size. FOURTH LARGEST OCEAN - THE SOUTHERN OCEAN: The Southern Ocean lies at the bottom of the Earth, and completely encircles the continent of Antarctica. It was called the Antarctic Ocean until the year 2000. FIFTH LARGEST AND SMALLEST OCEAN - THE ARCTIC OCEAN: The Arctic Ocean is located at the top of the planet. It is 5.5 million square miles. It sits north of Asia, North America, and Europe. The Arctic Ocean is very cold and is often covered with sea ice. Living conditions there are further complicated by the fact that there is very little light in the winter, and sunshine round the clock in summer. Only the animals and organisms that are particularly adapted to such extreme climates can survive there. Some of the animals that live there have a lot of fat and fur to keep them warm, and other animals have a chemical in their bodies that keeps them from freezing.

WHAT ARE THE OCEAN ZONES?

EUPHOTIC ZONE: The euphotic, or sunlit, zone is the area at the top of the ocean where the sunlight penetrates the water down to 600 feet. It is in this layer of the ocean that more than 90% of the ocean's marine life exists. Even though they live underwater, they need sunlight to live. More sunlight is available the closer the animals are to the surface of the water. The further down you go in this 600-foot zone, the less sunlight is available. All the ocean's plants live within a depth of 600 feet, because of their need for sunlight for photosynthesis. The sunlit zone is the top part of the ocean, and is the warmest part of the water. DISPHOTIC ZONE: The disphotic, or twilight, zone is the area beneath the top 600 feet of ocean that extends down to 3,000 feet. Animals that don't need so much light can live in this zone. At this depth, the water is hard to see through, murky and dark. The twilight zone is the middle part of the ocean, and is not as warm as the top of the water. APHOTIC ZONE: The aphotic, or midnight, zone is the area beneath the top 3,000 feet of water. Sometimes the water can be extremely deep, down to 35,000 feet. Animals that can survive in this inky black water where the sunlight never reaches have adapted themselves to live and find food near the sandy, barren ocean floor, where cracks in the Earth's crust spew out gases and minerals. The midnight zone is the bottom part of the ocean, where near-freezing temperatures, total darkness, and extreme pressure make life for all but the most adaptable utterly impossible.

WHAT ARE SOME OF THE ANIMALS THAT LIVE IN THE OCEAN?

PLANKTON: Plankton are tiny marine organisms that float throughout the top 600 feet of the water in oceans. Although they are very tiny, plankton are the most important food source in the oceans for many marine plants and animals.

CORALS AND JELLY FISH: Reef-builders such as corals live in the tropical oceans in colonies, and they live in mostly shallow waters. Many different animals combine to form coral reefs, some living and some not living. Part of corals is the calcium and animal bi-products and skeletons that come from these animals. Part of corals is the actual living organisms. Some are sea anemone, some are coral polyps. All need sunlight streaming down through the water to live. Corals look like plants but are really animals. Corals eat plankton, very tiny ocean animals, which they catch by using stingers on their tentacles. Corals also eat algae, which also require sunlight to live. The Great Barrier Reef off the coast of Queensland, Australia is the Earth's largest colony of corals. The second largest is located off the coast of Belize, South America. Coral reefs grow at a very slow rate, and may take as long as 100 years to reach one inch wide. Coral reefs can be destroyed very quickly, however. They can be damaged by human touch, by people dropping anchors on them, by large deposits of silt or sand covering them, by anything blocking the sunlight, by the use of poisons and dynamite by fisherman, and by the destruction of their algae food from sewage and pesticide runoff into the ocean. Corals are very important to ocean fish and other little animals that swim in and out of them to hide from predators. In this way, corals provide shelter and protection to many animals.

Jelly fish are in the same family as corals, and are invertebrates, meaning they have no bones or skeletons. They come in many shapes and sizes and colors. Some jellies are one inch across, some are seven feet across. Jellies have tentacles that hang down to catch food, and six to eight arms that move that food into the mouth. They may have short tentacles, or tentacles that grow to one hundred feet long. Jelly fish find it difficult to move horizontally, but can move effectively vertically, either up or down, by sharply contracting their bells to propel themselves up or by casually floating downward. To move horizontally, jellies use ocean currents and tides to take them sideways. Jellies eat mostly plankton and other jelly fish; sometimes they eat fish and crustaceans. Sunfish and sea turtles and other marine animals eat jelly fish, as some people in Asia eat them. Some jelly fish are poisonous and may give harmful burns to people that they touch. All jelly fish that have a blue or purple float, in particular, should be avoided by humans, since their tentacles and barbs contain a painful poison. They are dangerous in the water and on the beach. Swimming in waters where jellies are visible is dangerous because their tentacles are under the water, and may trail out dozens of feet. Some tentacles may stick to you and their poison may make swimming impossible. Many jelly stings occur after storms when tentacles have become detached and are not visible as they float by under the surface of the ocean.

MOLLUSKS: This includes cephalopods such as octopus, squid, nautilus, and cuttle fish; bi-valves such as scallops, mussels, clams, muscles, and oysters; gastropods such as slugs and snails; and polyplacophora such as chitons.

Mollusks are all soft-bodies sea animals, most with protective shells. Snails, oysters, and most animals that live in seashells such as conchs, are all mollusks. A few mollusks have learned to live without their protective shell, such as sea snails, octopus, and squid, and have developed other ways of guarding against enemies. There are over 112,000 species of animals in the phylum of mollusks. Only a few mollusks live in freshwater. Many mollusks are very small and live in colonies.

View of Oyster bed at low tide, 5 miles below

Brunswick, Glynn County, Georgia. USGS. 1895 - C.D. Walcott

Some mollusks are much larger, like the colossal squid, whose tentacles attain lengths of forty-six feet. Giant squids eat deep-sea fish and other smaller squids. They are eaten by sperm whales, Pacific sleeper sharks, southern elephant seals, and albatross, a large bird that feeds on beached remains. These gigantic squids have rarely been seen and we rely on beached specimen fragments to put the whole picture together. These squids are about the same length as giant squids, but their body is larger. A squid's tentacles have suction cups on them with little serrated teeth around them, that helps them hold on to their prey or their enemies. Many whales bear the scars of these suction cups on their skin, indicating a fight to the death for the whale to have the giant squid for lunch. All squid use dark ink to shoot out as evasive camouflage when they need to rapidly flee from an enemy.

The common octopus is a very intelligent mollusk (a cephalopod) that can actually solve problems, such as unscrewing a jar to get at its favorite food inside, which is a lobster. Octopus and squid are eaten by people.

Some mollusks may harm people. An octopus may bite, inflicting a poison that could cause problems to the victim. Clams and oysters and muscles are bi-valves that filter water through their shells and any bacteria, sewerage, "red tide" or harmful sea bacteria, or other pollution in their watery habitat can easily be absorbed into their bodies. Eating these contaminated bi-valves could make people very sick. Also a lot of people are simply allergic to bi-valves and cannot eat them anytime.

EELS: Eels look like snakes in the water, but they are really fish. They live in holes called eel pits along the bottom of the ocean, in their habitat. There is only one eel that lives in fresh water - the rest live in salt water. Eels are eaten by people, but since their blood is partly poisonous, they must be cooked and not eaten raw. Eels are various sizes, from two feet to sixteen feet long. Moray eels grow to about five feet long, and are camouflage colored on their bodies and also inside their mouths so that they can sit for long periods of time waiting for their prey to come on in. They have two sets of jaws: the first set grabs the prey, and the second set is in the throat to pull the food down. Both sets of jaws in the moray eel contain teeth. Moray eels eat octopus, squid, fish, shrimp, and other sea animals. They like to hunt at night. During the day, they like to be in their holes. They are eaten by groupers and barracudas. It is not advisable for people to eat moray eels due to the level of bacteria they contain that is not good for people. They typically do not attack people, but may bite to defend themselves. Their teeth contain a lot of bacteria that can prove dangerous to people, if bitten. Moray eels like warm ocean waters.

SHARKS, SKATES, RAYS: These are fishes with cartilage rather than bones. Sharks are scary creatures but many of them would not hurt people. Many sharks have many rows of replaceable teeth so that when one breaks off another takes its place.

Sharks range in size from nine inches (pygmy shark) to nearly forty feet (whale shark). Like other fish, sharks take in oxygen by passing water through their gills. The bull shark is the only shark that survives in fresh water. The other sharks must live in sea water. Shark tails come in many shapes and sizes, but all help the shark to propel himself forward in bursts of speed and help him to turn quickly while swimming, so that he can catch prey.

Most sharks are meat eaters that eat fish - some eat people. The whale shark eats a lot of plankton. It is thought that most sharks may live twenty to thirty years, and others up to one hundred years. There is scientific evidence to support the fact that sharks lived 370 million years ago. Proof of this shark's existence, Cladoselache, has been found in Tennessee, Ohio, and Kentucky, an area that was once ocean. Megalodon was a huge white shark, about forty feet long, that lived during the time of the dinosaurs. Great white sharks are modern sharks that have sparked fear in people due to instances of their grabbing swimmers in warmer waters. Shark attacks have been documented by many different sharks, however. The warmer waters off the Gulf Coast in the southern U.S. and off the coast of Australia attract many kinds of sharks.

Other sharks are reef sharks, mako, tiger, hammerhead, thresher, basking, nurse, dog, whitetip, blue, and bull, etc. Some sharks are hatched from eggs, while others are born alive. Young sharks are called pups.

Sharks have an incredibly strong sense of smell, affording them quick location of prey and injured prey - they can smell the tiniest drop of blood from miles away and zero in on it. For that reason, swimmers are urged to leave the water if they should cut themselves, and people who are surf-fishing should take care by not hanging fish on their belts. Most sharks also can detect the electromagnetic field of an animal or fish, can hear very well, and their sight is excellent. They are true expert predators. Although all sharks are potentially dangerous to people, the only four that have attacked people in unprovoked situations are the great white, tiger, bull, and whitetip.

Major threats to sharks are water pollution and over fishing of them or their prey. Finning is a practice that is outlawed in U.S. coastal waters which involves someone cutting off the dorsal fin of the shark and tossing him back into the water, where he immediately dies because he cannot swim. Fins are considered a food delicacy in Asia. Other sharks are hunted for their meat, and some people just like to kill them because they are considered sea monsters, even in this modern world.

The most famous fiction book about sharks was "Jaws" by Peter Benchley. Non-fiction books about sharks were written by Jacques Cousteau.

Dry Tortugas National Park, Florida. Professor Gudger and a tiger shark caught off

Loggerhead Key at the Carnegie Institution Marine Biological Laboratory - 1913.

In rays and skates, the pectoral fins are greatly enlarged to form "wings" that propel the animal through the water. They have only a few scales, and no bones. They eat smaller animals and crustaceans. With their sleek flat bodies they can glide effortlessly along the bottom of their habitats in search of food. Rays' eyes and spiracles (holes for taking in water) are on top of their bodies so that they can lie partially covered with sand for camouflage. Most skates and rays are harmless, but some have barbs and spikes that can inflict harm. Steve Irwin, the crocodile hunter, was fatally wounded by a sting ray that flipped his barb to hit him in the heart. You can feed and touch rays that have had their poison barbs removed at some aquariums such as SeaWorld in California and Florida, and the Aquarium of the Smokies in Gatlinburg, Tennessee.

CRUSTACEANS SUCH AS LOBSTERS, CRABS, SHRIMP, AND BARNACLES: The seafood trade in lobsters alone tops over $1.5 billion each year! People love to eat lobsters, crabs, and shrimp. People eat clawed lobsters. They live on the sandy bottom of the ocean along the continental shelf. They are caught in traps. Lobsters eat live fish, worms, and other crustaceans. They hide in crevices and in rocks to eat their prey and to elude their enemies - they always bring their dinner home to eat it. Lobsters move by walking along the sandy floor, but can propel themselves backward fast if they have to. They don't usually eat plant materials, they are meat eaters. When they are young and small, they may be eaten by cod, flounder, octopus, monk fish, or dogfish. Like other crustaceans, lobsters periodically molt or lose and replace their hard outer covering. Since molting is dependent on having enough energy to do it, many older and larger lobsters molt only once in ten years. When they are molting, and vulnerable to predators, they stay inside the shelter of their homey rocks until their hard armor hardens. Lobsters' greatest enemies are man and octopus.

There are many different types of crabs such as Dungeness, stone, spider, Alaskan King, blue, and pea. Most crabs love to eat a mix of plant material and meat such as other crustaceans, mollusks, and worms. Some, such as blue crabs, are bottom scavengers that prefer to eat decaying organisms. Fishing for crabs is profitable: over 1.5 million crabs are eaten by humans annually. Sometimes people try to catch blue crabs in their molting stage so that they don't have to worry with the hard shell - these are called soft-shelled crabs. Soft-shelled crabs are fished in the Gulf of Mexico, but more often there is a higher yield in the Chesapeake Bay in Maryland and Virginia. Crabs' natural predators are octopus, sea turtles, otters, raccoons, halibut, eels, bass, drum, catfish, garfish, diving ducks, herons and egrets, and other larger crabs. Many species of crabs live in fresh water, but the rest are marine dwellers and are adapted to salty water. Most crabs bury themselves in the sand or mud and enter a torpor state during the winter. Most like to live in shallow waters. True crabs have five visible pairs of legs, therefore, King crabs and hermit crabs are not true crabs. Horseshoe crabs are only a very distant relative of crabs.

Shrimp are small crustaceans that live in both salty water and fresh water. Shrimp may be found in the Gulf of Mexico or in a mountain stream in Tennessee, although the ones in fresh water are very tiny. Like other crustaceans, they have been around for millions of years. They move by walking and by swimming. When shrimp are young and smaller, they float around in the water and eat plankton. Later, as adults, they live on the bottom, where they like to eat plants, very small clams, worms, and the occasional dead crab. Their main enemies, besides people, are other larger shrimp. Their good sense of smell leads them to their food. People usually favor wild-caught shrimp to farm-raised shrimp because they taste better, and they have not been fed drugs such as antibiotics.

MAMMALS OF THE OCEAN!

Even though some mammals live in the water, they still have the characteristics of land mammals:

they breathe air with lungs, they are warm-blooded,

and they nurse their young with milk from mammary glands.

These are some of the mammals that live in or hunt in salty waters.

The whales are drawn to scale, the walruses are not.

U.S. Fish and Wildlife Service. Permission to CoveBear. Drawing by Bob Hines.

CETACEANS - WHALES, ORCA, DOLPHINS, PORPOISES: Whales are mammals that live their whole lives in salty waters. Although whales never go on the land unless they are beached, they once lived on land millions of years ago, as did dolphins and porpoises. Some types of whales are humpback, blue, narwhal, beluga, sperm, and right. Killer whales are orcas, technically not whales at all, but are more closely related to dolphins.

Baleen whales have a sieve-like structure in their jaw that seines out plankton - they are very large whales but they eat very tiny food. Toothed whales have, obviously, teeth - their prey is meat, as in squid and fish. Whales are very streamlined for ease of swimming like fish, but they are not fish. Whales, like other mammals breathe air into their lungs, and some, like the sperm whale, can hold their breath for two hours under the water. Some whales grow very large, like the blue whale, over one hundred feet long. That makes it the largest mammal in the history of the known natural world. Whales may live to be anywhere from forty to nearly two hundred years old. Their hearing, sight, and use of sonar is highly developed. They migrate with the changing seasons. Whales live in social groups called pods.

All whales have a thick layer of fat called blubber under their skin, and this helps to keep them warm in colder waters, and gives them energy. It is this whale blubber that people have wanted so badly through the centuries. Back in the times of no electricity and no petroleum, whale blubber was rendered down into whale oil, and used for light and heating. Today whale oil is used as a lubricant in the place of oil, and whale meat is sold and eaten in countries where whaling is legal, such as Canada and Japan. Other places where whales are allowed to be killed are Greenland, the Faroe Islands, Grenada, Iceland, Indonesia, Russia, and the United States.

Some of these countries, such as the U.S. allow minimal hunting of whales by their native peoples such as the Inuit (Eskimos) who rely on the whale for sustenance (oil and meat). Some are granted permission by the International Whaling Commission. Not all countries belong to or abide by the IWC.

The hunting of whales, or whaling, dates back to 6,000 B.C. and has led to the extinction of several kinds of whales. People opposed to whaling cite good reason for not doing it. Whales are long-lived creatures that take a long time to mature. Their offspring stay with them for many years before growing up. Also, the harvest of the whales in itself, is tortuous and painful to the animals, which have a high intelligence. The whales that have become extinct are the gray in the northwest Pacific and the gray in the Atlantic. Whales that are termed critically endangered are the bowhead and the (white) beluga in Cook Inlet. The species of whales that are officially endangered are the blue, sei, fin, north Pacific white, north Atlantic white, along with several subspecies. Other humpback, sperm, and beluga whales are classified as threatened.

Conversely to whale hunting as a profitable occupation is whale watching as a good way to make money. Eco-tourism is on the rise, and many people pay a lot to see whales and other animals. Iceland, Brazil, Argentina, and Africa promote whale watching and invite people to come and see their whales.

Dolphins and porpoises are smaller cetaceans, also mammals, also of high intelligence, that live in salty waters and eat fish and squid. There are nearly forty species of dolphins including common, bottle-nosed, blue, white, spotted, and more. Their hearing, sight, and sonar is acute. Dolphins, like whales, live in social groups called pods. Dolphins are one of the few natural enemies of sharks, frequently joining other dolphins to ram a shark into a fatal situation. Porpoises closely resemble dolphins, except for their teeth which are flattened, whereas dolphins' teeth are more pointed; also, porpoises tend to be rounder and shorter and smaller than dolphins. Porpoises are rarely trained for tricks in zoos, not doing as well in captivity as dolphins.

Seals are mammals that hunt in salty waters. This is a bearded seal, in Alaska.

U.S. Fish and Wildlife Service. Alaska Library. Permission to CoveBear.

WALRUSES, SEALS, AND SEA LIONS: Fin-footed mammals that live near the ocean and hunt in the salty waters, are called walruses, seals, and sea lions. Seals may have evolved from a dog-like creature about 23 million years ago. Walruses, seals, and sea lions are bullet-shaped for fast swimming, and use their fins to paddle and change direction.

Walruses live only in the Arctic region, either in the Pacific or the Atlantic Oceans, and love to eat clams and other mollusks. They are large mammals, with large tusks and large flippers. They may weigh as much as 4,500 pounds. Seals slow down their heart rate as they dive, and their nostrils automatically close as they dive. They can hold their breath up to two hours under water. All of these animals use a layer of fat to keep warm and for buoyancy and warmth, and all grow hair or fur too. In addition, seal fur may have an undercoat or extra coat of fur. All have good eyesight and hearing. Their enemies are people who hunt them for fur, polar bears, sharks, and orcas. All seals and sea lions like to eat squid, fish, and shellfish. Leopard seals will eat penguins if they have the chance. Some seals may eat other smaller seals. Elephant seals live in Antarctica and they can be identified by the bulls that have large noses, around the age of eight years old. These male seals have harems of up to fifty females. Some types of seals may be hunted by polar bears.

U.S. Fish and Wildlife Service. Permission to CoveBear. Drawing by Bob Hines.

WHAT ARE SOME OTHER ANIMALS THAT LIVE AND HUNT IN THE OCEAN?

- STARFISH, SEA CUCUMBERS, AND SEA URCHINS - SEA DRAGONS, SEA HORSES, AND PIPE FISH -

- PORCUPINE FISH, BLOWFISH, AND PUFFERS - SPONGES -

- MANY DIFFERENT TYPES OF FISH - SEA TURTLES

- CLICK HERE FOR POLAR BEARS -

- BIRDS SUCH AS SEAGULLS AND PELICANS -

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