Seas and Oceans

By: Laura Klappenbach







Seas and oceans stretch from pole to pole and reach around the globe. They cover more than 70 percent of the Earth's surface and hold in excess of 300 million cubic miles of water. The world's oceans conceal a vast underwater landscape of submerged mountain ranges, continental shelves, and sprawling trenches.

Since the ocean habitat is so extensive, it may be broken down into several smaller subhabitats:

inshore waters - the shallowest areas of the oceans that line coastal areas, formed by continental shelves.

open sea - the vast deep waters of the oceans.

The open sea is a stratified subhabitat, with light fliltering down a mere 250 meters, creating a rich habitat where algea and planktonic animals thrive. This region of the open sea is referred to as the surface layer. The lower layers, the midwater, the abyssal zone, and the seabed, are shrouded in darkness.

Seas and oceans stretch from pole to pole and reach around the globe. They cover more than 70 percent of the Earth's surface and hold in excess of 300 million cubic miles of water (Luhr 2003). The world's oceans conceal a vast underwater landscape of submerged mountain ranges, continental shelves, and sprawling trenches.

The geologic features of the sea floor include mid-ocean ridge, hydrothermal vents, trenches and island chains, continental margin, abyssal plains, and submarine canyons. Mid-ocean ridges are the most extensive mountain chains on earth, spanning some 40,000 miles across the sea floor and running along divergent plate boundaries (where tectonic plate are moving away from one another as new sea floor is being churned out from the Earth's mantle).

Animals of Seas and Oceans:
Life on earth first evolved in the oceans and developed there for most of evolutionary history. It is only recently, geologically speaking, that life has emerged from the sea and flourished on land. The animal inhabitants of seas and oceans range in size from microscopic plankton to massive whales.