This big blue planet we call home gets its fabulous blue color from the water that covers most of its surface. Over 70% percent of the earth is covered by ocean. Most of the world’s oceans are in the southern hemisphere, taking up about 85% of the surface area from the equator to the South Pole. Of all the water in the world 99% of it is seawater. There are more gallons of water in our oceans than there are numbers to count them with.

Every living thing on earth, from the tiniest microorganisms, to the dense jungles of the rainforest, to the mighty whales, has one thing in common; all require water for survival. Scientists believe that life on earth first began in the oceans, and then later spread onto land. The greatest numbers and diversity of life on earth can be found living where the water supply is greatest – in the sea. Though the largest creatures in the world can be found in the incredible open expanse and depth of the sea, most of the creatures living in the sea are smaller than your thumb. And there are many, many more living things in the sea then there are on land.

The oceans are so close, so familiar, and so much a part of our lives, yet life beneath the sea is as foreign to us as another planet. As vast as the oceans are, there is so much about them we still don’t know and we are only just beginning to understand. The oceans are much deeper than anything on land is high; the deepest place in the ocean is over seven miles down, while the highest elevation on land is just over five miles into the upper reaches of our atmosphere.

Scientists have been using brand new, sophisticated technologies, which have allowed them to collect a lot of data on the ocean, such as temperatures at different depths and locations around the world. The data are showing that the oceans of the world seem to have their own seasons. Scientists have found that warmer and cooler ocean waters are constantly churning and mixing, affecting every living thing in the food chain. As these warmer and cooler waters slowly mix large areas of the undersea environment are affected by the “climate”, which can lead to population explosions in some species, or rapid die offs in others at certain times of the year. The waters in the ocean also have regular and predictable patterns of movement in the form of currents, much like the air currents in our upper atmosphere.

Another finding scientists have discovered from satellite data and infrared imaging shows that large-scale changes in temperature over large areas of the oceans are what drive the weather machine in our atmosphere. The widely publicized ocean-warming trend called El Nino seems to happen about once or twice a decade. It has widespread, sometimes catastrophic effects on weather around the world, and it begins with changes in the sea. The extreme weather it brings is a result of an unexplained warming of the east Pacific Ocean, and it plagues normally wet countries with long periods of drought, while it drenches usually semi-arid to arid climates with torrential rains and flooding.

New technologies and the development of highly maneuverable submersible crafts have allowed scientists to go down to explore the deep ocean. In recent years, scientists have been able to see volcanic vents on the sea floor and film them spewing scalding hot, mineral rich waters into the surrounding sea. Some fascinating life forms have been discovered living in these unthinkably hostile environments where the sunlight never shines, the temperatures are extremely hot, and the pressure is crushing. The surprising discovery of life thriving in a place we thought no life ever could has made science change the way we define life. These discoveries have even shed new light on how life on earth probably first began. Every living species on earth has evolved from these earliest, most primitive one-celled organisms that emerged in the boiling, primeval seas. Science is continually discovering new species of living things down in the depths of the sea. We are just beginning to understand how deep ocean creatures are able to adapt, survive, and even thrive in the seemingly inhospitable conditions of the deep, deep oceans. With so much still to discover and learn about the sea, it makes being a scientist of the ocean an exciting field.

Understanding Ocean Zones...