Ocean smoothly into oceans of supercritical hydrogen. The atmosphere of Venus is 96.5% carbon dioxide, which is a supercritical fluid at its surface. On other bodies: Ocean An ocean () is a body of saline water that composes much of a planet's hydrosphere. On Earth, an ocean is one of the major conventional divisions of the World Ocean. These are, in descending order by area, the Pacific, Atlantic, Indian, Southern (Antarctic), and Arctic Oceans. The word "ocean" is often used interchangeably with "sea" in American English. Strictly speaking, a "sea" is a body of saline water (generally a division of the
Largest-scale trends in evolution not yet been empirically confirmed. Evolutionary theory might not predict largest-scale trends, but there may be such trends nonetheless. McShea (1996) looks at the empirical evidence for a trend towards increasing complexity in Metazoan fossils. He concludes that the evidence is not decisive and further investigation is required. Largest-scale trends in evolution The history of life on Earth seems to show a clear trend; for example, it seems intuitive that there is a trend towards increasing complexity in living organisms. More recently evolved organisms, such as mammals, appear to be much more complex than organisms, such as bacteria, which have