Seas are the waters of the Earth surrounding the continents and all are connected to each other. As opposed to the seas, lakes and rivers on land are called inland waters. Three quarters of waters and seas cover the Earth’s surface, and only barely a quarter is actually dry land. In that sense, our planet should rather be called Ocean! This would be apt, as it is exactly the oceans that set the Earth apart from other planets in the solar system. Seen from outer space, we live on a blue planet. 97 percent (1370 million cubic kilometers) of the Earth’s waters are contained in the oceans, and only about 2 % is in the ice sheet of Greenland and Antarctica. The small remaining percentage includes lakes and rivers, and also the water content of the atmosphere.
The seas are the cradle of life
The oceans not only dwarf continents in size, but also in terms of highest and lowest points. The deepest precipice on land is the Grand Canyon (USA) with only 1,800 meters (1.1 miles), but in comparison with oceanic trenches, this is almost nothing. The deepest point in our oceans is at 11,034 meters (6.86 miles) below sea level, in the Vityaz Trench, which is a part of the Mariana Trench (located East of the Philippines).
Even the biggest mountains on Earth, a mid-ocean ridge of a length of 60,000 km (approx. 37,300 miles) and a width of up to 4,000 m (approx. 2,500 miles) and stretching though all the three oceans, is actually not on land, but underwater. We should always remember that the seas are the cradle of life. It was there in the seas that from the simplest forms, life evolved, and stayed under water for the first three billion years. Only about 400 millions of years ago did the first plants and animals conquered dry land. We are also reminded of the marine origins of humans by the gill arches and gill slits that human embryos possess for a short time in their development. Human foetuses grow in the amniotic sac, in a sac of membrane filled with liquid.
It was in the sea that the first molecules of oxygen were produced (as a side-product of photosynthesis), which made life on land possible in the first place and still provide the vital foundation for life on land. The oxygen production of marine plants lead to the creation of the ozone layer in the stratosphere (at an altitude of 15 to 50 km or 9 to 31 miles), which filters the ultraviolet radiation of the sun, and makes life possible on land. Nobody knows exactly how many species there are living in our oceans, but it is estimated that the number may be as high as 10 million or more. Only 300,000 of these are scientifically described as we speak.
The Atlantic around Madeira
Madeira lies in the Atlantic, at the Eastern rim of the Mid-Atlantic Ridge, and is slowly shifting to the East.
The island has a narrow continental shelf, and already after a few kilometers, its slopes drop to depths of 4,000 to 5,000 meters (2.5 to 3.1 miles).
This is especially important for large sperm whales, as they hunt in the depths of the seas for their favorite food, deep-sea squids.
A peculiarity of the Atlantic here is that it is relatively poor in nutrients. This is also one of the reasons why the waters around Madeira are so clear
and allow such good visibility at greater depths. The human eye can perceive sunlight here down to a depth of about 300 meters.
The water temperatures on the surface vary between 17 and 25 degrees Celsius depending on the time of the year.
The tidal range, the difference between low and high tide lies between 0.34 and 2.46 meters (1’1.38’’ to 8’0.85’’).
Here’s a video message from Ric O’Barry. Also a simple but important message from Jane Goodall speaking out for the dolphins.
And finally a sequence of videos that tell the true story behind the dolphinaria and orcanaria.
– The true story behind the dolphinaria and orcanaria –
At last but not least we have collected and chosen some of the petitions that
are very close to our hearts – please sign and take action!
STOP THE DELPHINARIUM IN MADEIRA
STOP THE SLAUGHTER OF PILOT WHALES
BY FAROE ISLANDS
Causes . Avaaz
STOP THE DOLPHIN HUNT IN THE COAST OF PERU
Avaaz . Causes
STOP THE LIVE CAPTURE OF MARINE SPECIES
SUPPORT HOMES FOR WHALES – MARINE PROTECTED AREAS
HELP SECURE THE 2 LARGEST OCEAN SANCTURIES
IN THE WORLD –ANTARCTICA
Fights for whales, seals, sharks, dolphins and the protection of the seas
effectively and uncompromisingly
Interesting NEWS and information from the world of open and
The former WDCS changed the name to WDC: The international Whale and Dolphin Conservation Society (WDCS)
is one of most active non-profit organisations worldwide working exclusively for the protection of whales and dolphins and their habitat.