Ch. 13 OceansCh. 13 Oceans

NotesNotes

OceansOceans

71-75% of Earth’s surface is covered by 71-75% of Earth’s surface is covered by water. water.

4 main oceans were formed within the last 4 main oceans were formed within the last 300 million years.300 million years.– Artic OceanArtic Ocean– Indian OceanIndian Ocean– Pacific OceanPacific Ocean– Atlantic OceanAtlantic Ocean

Salts have been added to the ocean for billions of years.

Salinity is the measure of the amount of dissolved salts in a given weight or mass of liquid.

Characteristics of Ocean WaterOcean water is salty because salt has been added to the ocean for billions of years.As water flows to the ocean, it dissolves minerals and materials on land that eventually end up in the ocean.

Temperature Zones of Ocean Water

Temperature decreases as you go deeper.

3 temperature zones:1. Surface zone: 0-300 m deep, surface currents

move heated water by sun with cooler water below

– Surface temperatures change with the seasons and amount of sunlight it receives.

= OR

2. Thermocline:300-700m deep, temperature drops faster in this zone than the others

3. Deep Zone: 700m to bottom of ocean, average temp. is 2 degrees Celsius

The ocean stabilizes Earth’s conditions by absorbing and retaining thermal energy.

Ocean FloorContinental Shelf: begins at shoreline and slopes toward open ocean.

Continental Slope: begins at edge of shelf and continues down to flattest part of ocean floor, b/w 200-4000 m

Continental rise: base of continental slope, boundary b/w continental margin and deep-ocean basin

Abyssal plain: broad, flat portion of deep-ocean basin, covered by mud and remains of marine organisms

Mid-ocean ridges: mountain chains formed where tectonic plates pull apart or diverge making new crust

Rift valley: forms b/w mountains as they build up

Seamounts: individual mountains of volcanic material, form when magma pushes up b/w tectonic plates

Ocean trenches: cracks in ocean floor, form when oceanic plates are forced underneath another plate

Study ocean floor by actually looking at it, using sonar, and satellites.

Ocean Life

Organisms are placed in each group according to where they live and how they move.

3 main types of marine life:– Plankton– Nekton– Benthos

1. Plankton: organisms that float at/near ocean surface.

Most are microscopic! (tiny)

Divided into 2 groups:– Phytoplankton: plantlike– Zooplankton: animal-like

2. Nekton: free swimming organisms of the ocean, most abundant in surface waters– Includes mammals like: whales, dolphins, sea lions,

and lots of fish!

3. Benthos: organisms that live on/near ocean floor; live in mud, sand and rock– Includes crabs, sea stars, worms, coral, sponges,

seaweed, and clams

Benthic Environment

Divided into ecological zones based on the different types of benthos living there.

1. Intertidal Zone: shallowest zone located b/w low tide and high tide limits; exposed to sun and air as tides change; clams, oysters, barnacles, crabs, and seaweed survive here

2. Sublittoral Zone: begins at low-tide limit and extends to edge of continental shelf.

Benthic Environment

Most stable zone, coral and fish live here

3. Bathyal Zone: from continental shelf to abyssal plain; 200-4000m deep; plant life is scarce, animals include sponges, sea stars, octopi.

4. Abyssal Zone: on abyssal plain; crabs, sponges, worms, sea cucumbers; little is known about this zone due to the depth

Benthic Environment

5. Hadal Zone: deepest zone at floors of ocean trenches; few species live here

Pelagic EnvironmentEntire volume of water in the ocean and the marine organisms that live above the ocean floor.

2 major zones:– Neritic zone: covers continental shelf, largest

concentration of sea life due to amount of sunlight

– Oceanic zone: covers everything else but continental shelf; water is cooler in temperature; pressure is greater; very little sea life found here