1. Composition & Characteristics of Oceans

2. Earth’s oceans are all connected, however, scientists separate the ocean into five main oceans:
Pacific Ocean – largest and deepest of the oceans; larger than all of Earth’s continental land mass put together
Atlantic Ocean – half the size of the Pacific, covers about 20% of Earth’s surface
Indian Ocean – the third largest ocean that is located between India, Africa and the Indonesian Islands
Southern Ocean – surrounds the Antarctic continent and is covered by ice part of the year
Arctic Ocean – smallest and shallowest ocean that is located near the North Pole and is also covered by ice part of the year

4. seawater – water from a sea or ocean that has an average salinity of 35 ppt (parts per thousand), or one kg of ocean water contains about 35 g of salt   salinity – measure of the mass of dissolved solids in a mass of water

5. Oceans are divided into zones based on physical characteristics that include sunlight, temperature, salinity and density

6. Surface zone – area of shallow seawater that receives the most sunlight; organisms that perform photosynthesis are located here Middle zone – receives very little sunlight and of it only the blue-green wavelengths Deep zone – plants that photosynthesize are not found here because there is NO light; many organisms produce light using chemicals in a process called bioluminescence

8. Temperature – temperature changes from surface to about 1000 m depending if located in polar or tropical regions Salinity – top 500 m of water is saltier in warmer water than polar water since it evaporates faster leaving behind salt at surface Density – ocean water is layered since cold water is denser than warm water and salt water is denser than fresh water