SOME INTERESTING FACTS AND INFORMATION ABOUT OCEANS

OCEANS

Humpback whale sounding in the Chatham Straits off Alaska

Life began in the oceans. Covering two-thirds of the Earth's surface, in the twenty-first century oceans remain crucial for our survival; for regulating climate, providing us with resources like fish and minerals, and potentially offering us cures for disease.

The oceans are home to half the world's biodiversity, and new species are being found almost daily. In fact, we know more about the moon than we do about the deep ocean. Marine life has adapted to exploit every niche, from the poles to the tropics, from estuaries to the deep ocean.

We take a look at the oceans and seas along the meridian, their importance to man, the diversity of wildlife that inhabit these waters, and some important conservation issues.

WILDLIFE

A Black-browed Albatross. Albatrosses are the largest of the sea-birds.

The oceans along the meridian line are home to a diversity of habitats and wildlife. Inshore habits like estuaries, mudflats and mangroves offer feeding and roosting areas for birds, and provide sheltered nursery areas for fish and shellfish.Offshore, fish species like tuna, toothfish and sharks, and birds like albatross and petrels patrol the vast oceanic expanses.

Phytoplanton (the marine equivalent of terrestrial grasslands), seaweeds and seagrasses form the base of the food web. In the Southern Oceans the stark seasonality provides a bounty of plant and animal plankton. The estimated production of phytoplankton in the surface waters of the Southern Ocean is 610 million tonnes a year.

Humpback Whale breaching in the waters off Alaska

Zooplankton (the marine equivalent of insects) feed on the phytoplankton and support abundant schools of squid, fish, and consequently a variety of larger marine creatures like seals, seabirds and whales. Half the zooplankton in the Southern Ocean are krill, a shrimp-like animal. Several species of filter feeding whale, like humpbacks, feed directly on krill. In 1994 the Southern Ocean was declared a sanctuary for the great whales.

SOME INTERESTING FACTS AND FIGURES

The cliffs of Harwick Head in the Orkney Islands are home to many seabirds

Did you know that?

• In some places the ocean is deeper than Mount Everest is high; for example, the Mariana Trench and the Tonga Trench in the western part of the Pacific Ocean reach depths in excess of 10,000 metres (32,800 feet).
• If all the land in the world was flattened out, the Earth would be a smooth sphere completely covered by a continuous layer of seawater 2,686 metres deep.
• Ocean water and ice make up almost 98 percent of all the water on Earth.
• Icebergs are formed by the calving (detaching of parts) of glaciers or of inland ice that reaches the sea. The valley glaciers of Greenland produce some 12,000 to 15,000 sizable icebergs every year.
• The Pacific Ocean is the largest ocean, containing more than twice the volume of water as the Atlantic Ocean.
• Earth is the only planet in our solar system to have oceans.
• Marine fisheries throughout the world catch over 80 million tonnes of fish every year.
• Hundreds of millions of tonnes of toxic chemicals, sewage, industrial waste, agricultural run-off and oil are dumped in the oceans every year – and up to 80 per cent originate on land.
• Each year 20 million tonnes of fish, seabirds, marine mammals and other ocean life are killed unnecessarily by indiscriminate fishing practices.
• Hydrothermal vents, fractures in the sea floor that discharge hot seawater laden with hydrogen sulphide, support the only ecosystem known to run on chemical energy rather than energy from the sun, including mussels, large bivalve clams, and huge tube worms.
• The deepest known point in the ocean is the Mariana Trench which reaches depths of over 36,000 feet (11,000 meters).