Marine Biology (2+1)

Introduction

The ocean currently covers 71% of the earth’s surface. Around two thirds of earth’s land area is found in the Northern Hemisphere which means the ocean covers 61% of the total area.  The rest (39%) is land however the southern Hemisphere the ocean covers of the area as much as 80% of the area and the rest (20%) is land.   marine ecosystem is the largest aquatic system of the planet which includes oceans, coral reefs, and estuaries. Since it is a single large and a complex  system,  it is very difficult to deal with it as a whole. Therefore the oceanographers have divided the ocean into many zones according to physical characteristics, mainly based on depth, light and temperature. The two major zones of the ocean are the entire sea floor, or bottom region of the sea, called the benthic realm and the watery region above the sea floor is called the pelagic realm. Each of these is further subdivided into many different zones based on  environmental conditions.