All About Oceans & sea
The earth’s oceans make up more than 70% of its total surface area. More than half of this area of salt water is more than 9000 feet deep!
There are actually just three distinctly separate oceans in the world today; the World Ocean, the Black Ocean and the Caspian Sea. The largest ocean on earth is the World Ocean, measuring in at an immense 361 million square kilometers. The World Ocean is continentally divided into five smaller parts, which include the Atlantic Ocean, the Pacific Ocean, the Indian Ocean, the Arctic Ocean and the Antarctic Ocean. Smaller portions of these oceans are typically classified as either seas, gulfs or straits.
The Mediterranean Sea unofficially became the world’s fourth ocean when the sea’s only outlet to the World Ocean, the Strait of Gibraltar, was closed due to the movement of the African continent.
The oceans of the world are home to the vast majority of the plant and animal species on earth, millions of which have yet to be discovered by man.
Ocean Facts
Did you know...?
Sharks attack some 50-75 people each year worldwide, with perhaps 8-12 fatalities, according to data compiled in the International Shark Attack File (ISAF). Although shark attacks get a lot of attention, this is far less than the number of people killed each year by elephants, bees, crocodiles, lightning or many other natural dangers. On the other side of the ledger, we kill somewhere between 20-100 million sharks every year through fishing activities.
Of the 350 or so shark species, about 80% grow to less than 1.6 m and are unable to hurt people or rarely encounter people. Only 32 species have been documented in attacks on humans, and an additional 36 species are considered potentially dangerous.
Almost any shark 1.8 m or longer is a potential danger, but three species have been identified repeatedly in attacks: the Great white, Tiger, and Bull sharks. All three are found worldwide, reach large sizes and eat large prey such as marine mammals or sea turtles. More attacks on swimmers, free divers, scuba divers, surfers and boats have been reported for the great white shark than for any other species. However, some 80% of all shark attacks probably occur in the tropics and subtropics, where other shark species dominate and Great white sharks are relatively rare.
An estimated 80% of all life on earth is found under the ocean surface and the oceans contain 99% of the living space on the planet. Less than 10% of that space has been explored by humans. 85% of the area and 90% of the volume constitute the dark, cold environment we call the deep sea. The average depth of the ocean is 3,795 m. The average height of the land is 840 m.
The oceans cover 71% of the Earth's surface and contain 97% of the Earth's water. Less than 1% is fresh water, and 2-3% is contained in glaciers and ice caps.
90% of all volcanic activity occurs in the oceans.
The speed of sound in water is 1,435 m/sec - nearly five times faster than the speed of sound in air.
The highest tides in the world are at the Bay of Fundy, which separates New Brunswick from Nova Scotia. At some times of the year the difference between high and low tide is 16.3 m, taller than a three-story building.
Earth's longest mountain range is the Mid-Ocean Ridge more than 50,000 km in length, which winds around the globe from the Arctic Ocean to the Atlantic, skirting Africa, Asia and Australia, and crossing the Pacific to the west coast of North America. It is four times longer than the Andes, Rockies, and Himalayas combined.
The pressure at the deepest point in the ocean is more than 11,318 tons/sq m, or the equivalent of one person trying to support 50 jumbo jets.
The top ten feet of the ocean hold as much heat as the entire atmosphere.
The lowest known point on Earth, called the Challenger Deep, is 11,034 m deep, in the Marianas Trench in the western Pacific. To get an idea of how deep that is, if you could take Mt. Everest and place it at the bottom of the trench there would still be over a mile of ocean above it. The Dead Sea is the Earth's lowest land point with an elevation of 396 m below sea level.
Undersea earthquakes, volcanoes and landslides can cause tsunamis (Japanese word meaning "harbor wave"), or seismic sea waves. The largest recorded tsunami measured 60 m above sea level caused by an 8.9 magnitude earthquake in the gulf of Alaska in 1899 traveling at hundreds of km/hr.
The average depth of the Atlantic Ocean, with its adjacent seas, is 3,332 m; without them it is 3,926 m. The greatest depth, 8,381 m, is in the Puerto Rico Trench.
The Pacific Ocean, the world's largest water body, occupies a third of the Earth's surface. The Pacific contains about 25,000 islands (more than the total number in the rest of the world's oceans combined), almost all of which are found south of the equator. The Pacific covers an area of 179.7 million sq km.
The Kuroshio Current, off the shores of Japan, is the largest current. It can travel between 40-121 km/day at 1.6-4.8 kph, and extends some 1,006 m deep. The Gulf Stream is close to this current's speed. The Gulf Stream is a well known current of warm water in the Atlantic Ocean. At a speed of 97 km/day, the Gulf Stream moves a 100 times as much water as all the rivers on earth and flows at a rate 300 times faster than the Amazon, which is the world's largest river.
A given area in an ocean upwelling zone or deep estuary is as productive as the same area in rain forests, most crops and intensive agriculture. They all produce between 150-500 grams of Carbon per square meter per year.
The sea level has risen with an average of 10-25 cm over the past 100 years and scientists expect this rate to increase. Sea levels will continue rising even if the climate has stabilized, because the ocean reacts slowly to changes. 10,000 years ago the ocean level was about 110 m lower than it is now. If all the world's ice melted, the oceans would rise 66 m.
The density of sea water becomes more dense as it becomes colder, right down to its freezing point of -1.9°C unlike fresh water which is most dense at 4°C, well above its freezing point of 0°C. The average temperature of all ocean water is about 3.5°C.
Antarctica has as much ice as the Atlantic Ocean has water.
The Arctic produces 10,000-50,000 icebergs annually. The amount produced in the Antarctic regions is inestimable. Icebergs normally have a four-year life-span; they begin entering shipping lanes after about three years.
Air pollution is responsible for 33% of the toxic contaminants that end up in oceans and coastal waters. About 44% of the toxic contaminants come from runoff via rivers and streams.
Each year, three times as much rubbish is dumped into the world's oceans as the weight of fish caught.
Oil is one of the ocean's greatest resources. Nearly one-third of the world's oil comes from offshore fields in our oceans. Areas most popular for oil drilling are the Arabian Gulf, the North Sea and the Gulf of Mexico.
Refined oil is also responsible for polluting the ocean. More oil reaches the oceans each year as a result of leaking automobiles and other non-point sources than the oil spilled in Prince William Sound by the Exxon Valdez.
The record for the deepest free dive is held by Jacques Mayol. He dove to an astounding depth of 86 m without any breathing equipment.
A mouthful of seawater may contain millions of bacterial cells, hundreds of thousands of phytoplankton and tens of thousands of zooplankton.
The Great Barrier Reef, measuring 2,300 km in length covering an area more extensive than Britain, is the largest living structure on Earth and can be seen from space. Its reefs are made up of 400 species of coral, supporting well over 2,000 different fish, 4,000 species of mollusc and countless other invertebrates. It should really be named 'Great Barrier of Reefs', as it is not one long solid structure but made up of nearly 3,000 individual reefs and 1,000 islands. Other huge barrier reefs include the barrier reefs of New Caledonia, the Mesoamerican (Belize) barrier reef, and the large barrier reefs of Fiji. The largest coral atoll complexes occur in the Maldive-Lakshadweep ecoregion of the central Indian Ocean and in Micronesia.
Fish supply the greatest percentage of the world's protein consumed by humans and most of the world's major fisheries are being fished at levels above their maximum sustainable yield; some regions are severely overfished.
More than 90% of the trade between countries is carried by ships and about half the communications between nations use underwater cables.
The swordfish and marlin are the fastest fish in the ocean reaching speeds up to 121 kph in quick bursts; the Bluefin Tuna (Thunnus thynnus) may reach sustained speeds up to 90 kph.
The Blue whale is the largest animal on our planet ever (exceeding the size of the greatest known dinosaurs) and has a heart is the size of a Volkswagen.
The Oarfish (Regalecus glesne), is the longest bony fish in the world. It has a snakelike body sporting a magnificent red fin along its 15.25 m length, a horselike face and blue gills, and accounts for many sea-serpent sightings.
Many fish can change sex during the course of their lives. Others, especially rare deep-sea fish, have both male and female sex organs.
One study of a deep-sea community revealed 898 species from more than 100 families and a dozen phyla in an area about half the size of a tennis court. More than half of these were new to science.
Life began in the seas 3.1 billion to 3.4 billion years ago. Land dwellers appeared 400 million years ago, relatively recently in geologic time.
Because the architecture and chemistry of coral is so similar to human bone, coral has been used to replace bone grafts in helping human bone to heal quickly and cleanly.
Ocean fact #1
Earth has five major oceans. The largest is The Pacific, located between the Southern Ocean, Asia, Australia and the western hemisphere, over an area about 15 times the size of the USA. It contains more than 25,000 islands. Ocean fact #2
The Challenger Deep is the lowest spot in all the world's oceans, located in The Pacific. To put its depth into perspective, if you dropped in Mount Everest (8,850 metres high), there'd still be more than a mile of ocean above it. Ocean fact #3
Australia's Great Barrier Reef covers an area bigger than Great Britain and can even be seen from space. The Reef is a collection of islands which are home to over 400 types of coral and among which live more than 2,000 species of fish. Ocean fact #4
Not for the fainthearted or weak-lunged, free-diving is deep-sea diving while holding your breath. In 1976, Jacques Mayol, 56, immortalised in Luc Besson's The Big Blue, dived 105 metres without breathing equipment. Ocean fact #5
Captain Matthew Webb was the first person to swim the Channel; in 1875 he took 21 hours and 45 minutes. The fastest was Christof Wandratsch, who in 2005 crossed in seven hours, three minutes and 52 seconds. David Walliams eat your heart out.
Ocean fact #6
Enjoy a spot of windsurfing on your summer holidays? Perhaps you wouldn't want to go as far as Brazilians Flavio Jardim and Diogo Guerreriro. In 2005 the record-holding pair travelled 5,045 miles along the Brazilian Coast. Ocean fact #7
The world's highest tides occur at the Bay of Fundy, which separates New Brunswick from Nova Scotia. At springtime, the difference between low and high tide can be 16.3 metres - about the height of a three storey building. Ocean fact #8
The Earth's longest mountain range is underwater. The Mid-Ocean Ridge runs around the globe from the Arctic to the Atlantic, via Africa, Asia and Australia. That's four times longer than the Andes, Rockies and the Himalayas combined. Ocean fact #9
The blue whale can grow up to 30 metres in length; the heart alone can be the size of a car. By the early 1960s blue whales were nearly extinct, but in 1966 whaling was banned and there are currently around 10,000 blue whales in existence. Ocean fact #10
The Arctic produces up to 50,000 icebergs – large chunks of ice that break away from glaciers and float in open sea – every year. They're classified by the International Ice Patrol as Growlers (the smallest bergs, just one metre tall) or Very Large (over 75 metres).
Oceans make up about 70 percent of Earth’s surface and contain lots of different salts: sodium, chloride, sulfate, magnesium, calcium, potassium, bicarbonate, and bromide. These salts enter the ocean through rivers, which, before entering pass over rocks and soil, and pick up salt along the way.
This salt builds up in the ocean because the only way water can leave the ocean is through evaporation. And when the water evaporates it doesn't take the salt with it. So you end up with less water, and the same amount of salt, resulting in a pretty salty sea.
The same thing can happen to a smaller, landlocked body of water, such as the Great Salt Lake in Utah, where water evaporates quickly in the desert climate—the lake has dropped 20 feet since 1849. A favorite pastime for visitors is to float on the lake like a cork, because the high salt content makes people more buoyant.
Where do octopuses and squids live?
They live in salt water from the tropics to temperate zones
What are the similarities and differences between squids and octopuses?
Octopuses and squids move by "jet propulsion", sucking water into a muscular sac in the mantle cavity surrounding their bodies and quickly expelling it out a narrow siphon.
Both octopuses and squids are related to snails and other molluscs. Unlike snails, octopuses no longer have any remnant of a shell. Squids possess a stiff structure known as a pen, that acts as a flexible backbone.
Both squids and octopuses have blue blood! Their blood is this colour because they use an oxygen-carrying molecule in their blood that contains copper.
Octopuses and squids have hard, parrot-like beaks. These are excellent for killing, and tearing pieces of flesh from their prey.
Octopuses live in dens on the sea floor. Squids live in the open oceans.
Octopuses use their eight sucker-lined arms to capture their prey and move about on the ocean floor. Squids have eight arms lined with suckers and two specialized tentacles that they use to reach out and capture prey.
Octopuses eat bottom-dwelling crustaceans. Squids eat fishes and shrimps. Some deepwater squids may be scavengers.
Octopuses pierce the shells of their prey, injecting poison that causes paralysis. They then release salivary enzymes, loosening the meat from the inner shell. Squids use their two specialized tentacles to quickly reach out and capture fishes. They tear off bits of flesh and scrape the meat into their mouths with their beaks.
How big are these animals?
Octopuses range in size from 1 cm to more than 5 m in length, while squids range from 1 cm to 20 m. The giant Pacific octopus has a life span of only four to five years, yet it can weigh 270 kg!
How do octopuses and squids move?
Octopuses and squids can swim in any direction and can alter their course quickly.
Squids use fins located on their heads to propel themselves when swimming at low speeds. These fins steer and stabilize the squids when moving slowly, and wrap around the body when they move quickly, by way of jet propulsion.
Most octopuses do not have fins as adults. Some deepwater octopuses are exceptions.
Do octopuses and squids live in schools?
Octopuses are solitary animals that live alone in dens.
Some squids live in large schools, others are solitary. Some squids school when young and become solitary later in life.
How do octopuses and squids reproduce?
The male octopus uses a specialized arm called a hectocotylus to transfer sperm to the mantle cavity of a receptive female. The female lays strings of fertilized eggs on the roof of her den. She guards, cleans and aerates the eggs with water expelled from her siphon until hatching—anywhere from 30 days to a year, depending on the species. The female may build a wall of rocks to seal off the den and will remain in the den until just before she dies, after the eggs have hatched.
Squids often mate in large groups, and attach their egg capsules to the ocean floor or to seaweed.
Most adult octopuses and squid die after reproducing. Their bodies are recycled in the food web, nourishing other animals, and ultimately providing food for their young when they hatch.
Are octopuses and squids dangerous to people?
Most poisons produced by octopuses and squids are too weak to harm humans. The blue ringed octopus is an exception. This Australian native produces enough poison to paralyze and kill a human. Our local red octopus, Octopus rubescens, can inflict a nasty nip when provoked.
Do humans eat octopuses and squids?
Yes.
On menus, squid may be called "calamari".
Black pasta is coloured using squid ink.
Greek restaurants sometimes serve pickled octopus, called octopothi.
How do humans harvest octopuses and squids?
Fishers trawl for octopuses using weighted chains that drag along the ocean floor, scaring the octopuses into a net. Another method involves lowering traps and pots which octopuses will use as shelters. Spear fishing and drift fishing are also practiced.
Fishers catch squids by jigging. They shine bright lights and drop lines into the water with special lures called jigs, which they jerk up and down, attracting squids to the light and movement. Recently, fishers have begun to use large seine nets that encircle the squids, forming pockets and trapping them. There are 15 major harvesting areas for squids worldwide, but only two have sustainable harvests today.
What other predators do squids and octopuses have?
Common predators of octopuses and squids are moray eels, fishes, seals, whales, sea stars and several species of birds.
How do octopuses and squids protect themselves?
Colouration: They can change colour and create countless intricate patterns on their bodies to blend with their surroundings.
High-speed swimming: Some squids travel at high speeds using their fins as wings to leap out of the water, briefly flying away from their predators.
Ink: Octopuses and squids can expel a dark cloud of ink from an ink sack. This confuses predators and gives the octopuses and squids time to escape.
Bioluminescence: Some squids produce light. In dark waters, this diverts attention by disguising their contours.
Schooling: Some squids seek protection in numbers, making it difficult for a predator to focus the attack.
Poison: Some octopuses and squids can release poisons to paralyze predators.
What senses do octopuses and squids have?
Touch: Octopuses are extremely sensitive to touch, but cannot discriminate between heavy and light objects.
Taste: Octopuses have taste receptors all over their bodies and are as much as 10 to 1000 times more sensitive to taste than humans.
Sight: Octopuses and squids have excellent vision, but may be colour-blind. Some have a 360 degree range of vision with eyes that are very similar in structure to human eyes.
Smell: Octopuses and squids register smell in small pits located beneath the eyes.
I have heard tales of octopuses and squids sinking ships. Can these be true?
In traditional narratives, a creature called a Kraken seized large boats and sank them. The animal they were describing may be the giant squid. Although this animal reaches 20 m in length, it is unlikely that these stories are entirely true
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