Friday, April 27, 2012

WIDE SEA (71% of Planet surface)

[Psalms 104:25]
So is this great and wide sea, wherein are things creeping innumerable, both small and great beasts.

An ocean (from Greek Ὠκεανὸς, "okeanos" Oceanus)[1] is a body of saline water that composes a large part of a planet's hydrosphere.[2] In the context of Earth, it also refers to major divisions of the planet's World Ocean, such as the Atlantic Ocean. The word "sea" is often used interchangeably with "ocean", but a sea is a body of saline water in a more inland location rather than a location in which it encompasses the land around it.

Earth's global ocean is the largest confirmed surface ocean on all observable planets. Approximately 71% of the planet's surface (~3.6×108 km2) is covered by saline water that is customarily divided into several principal oceans and smaller seas. Because it is the principal component of Earth's hydrosphere, the world ocean is integral to all known life, forms part of the carbon cycle, and influences climate and weather patterns. The total volume is approximately 1.3 billion cubic kilometres (310 million cu mi) with an average depth of 3,790 metres (12,430 ft). It is the habitat of 230,000 species known to science, however much of the ocean's depths remain unexplored and it is estimated that over 2 million marine species may exist.The origin of Earth's oceans is still unknown though they are believed to have first appeared in the Hadean period and may have been the point of origin for the emergence of life according to many theories of Abiogenesis.

Extraterrestrial oceans may be composed of a wide range of elements and compounds. The only confirmed large stable bodies of extraterrestrial surface liquids are the Lakes of Titan though there is evidence for the existence of oceans elsewhere in the Solar System. Early in their geologic histories, Mars and Venus are theorised to have had large water oceans. The Mars Ocean Hypothesis suggests that nearly a third of the surface of Mars was covered by water though Water on Mars is no longer oceanic. A Runaway greenhouse effect may have boiled away the global ocean of Venus. Compounds such as salts and ammonia mixed water are known to lower the freezing point potentially allowing water to exist in large quantities in extraterrestrial environments as brine or convecting ice. The Solar System's gas giant planets are also strongly believed to possess liquid atmospheric layers of yet to be confirmed compositions. Unconfirmed oceans are speculated beneath the surface of many dwarf planets and natural satellites, notably the ocean of Europa believed to have over twice the water volume of Earth. Oceans may also exist on exoplanets and exomoons, including surface oceans of liquid water within a circumstellar habitable zone. Ocean planets are a hypothetical type of planet with a surface completely covered with liquid.

And God created great whales, and every living creature that moveth, which the waters brought forth abundantly, after their kind, and every winged fowl after his kind: and God saw that it was good. And God blessed them, saying, Be fruitful, and multiply, and fill the waters in the seas, and let fowl multiply in the earth. (Gen.1:21-22)

230,000 Abundantly species live in the sea.
How many species are there in the sea? Some 230,000 recorded so far, all of which will soon be available to anyone at the click of a mouse.

The World Register of Marine Species is launched today by the Census of Marine Life. Once complete, it will provide the first definitive list of all known species in the world's oceans.

The Register is freely accessible online and includes descriptions of the species and photos. It will allow both the public and scientists to identify species they come across and easily recognise entirely new species.

Until now censuses have been incomplete, focussing on single species or regions, making proper assessment of the impact of humans on oceans difficult. "Convincing warnings about declining populations of fish and other marine species must rest on a valid census," says Mark Costello of the University of Auckland, co-founder of the World Register.

Jesse Ausubel of the Sloane Foundation, which funds the Census of Marine Life, says he was first struck by the need to catalogue marine species in 2000, when he realised the UN Environment Programme's Global Biodiversity Assessment had little information on what lived in the sea.

Lack of a list
Ausubel asked the author of the report's only chapter on marine life, Frederick Grassle of Rutgers University, US, how many species there were in the sea. He was told that the best estimate was between 1 and 10 million.

"I asked him if he could at least give me a list of the species that were known at the time," says Ausubel. Grassle was embarrassed to admit he could not. "How could there not be a list in the year 2000 of what we knew to live in the oceans?" marvels Ausubel.

Since then, the Census of Marine Life has worked to establish such a list. With the help of experts worldwide, they are painstakingly reviewing and compiling published records of marine species. Much of the work has focussed on identifying species given different names that are in fact the same.

The sperm whale, for instance, has been found to have 4 different Latin names, and one sponge species, the breadcrumb sponge, has 56.

Millions more
So far, the catalogue contains 122,000 species, about half the estimated 230,000 known species. It should be complete by 2010.

But there are still millions more ocean species to be discovered. Meeting in Belgium on 20-21 June, marine taxonomists discussed Grassle's estimate of between 1 and 10 million total marine species.

"We think that a million is reasonable," says Ausubel, adding that experts have little idea what the upper limit could be. The group hope to be able to make a more informed guess once they have finished cataloguing those that have already been described.

No comments:

Post a Comment