Transcript The Ocean
The Ocean The Continental Shelf • • • • 1st region of the ocean floor Can be as short as 19 meters Made up of the continental crust Ends at the continental slope Continental Slope • Average depth=3720 meters • Found at border of continental crust and oceanic crust • Sometimes slope is more like a steep cliff Abyssal Plain • Flat floor of the deep ocean • Mid-ocean ridges – Earth’s tectonic plates being split apart – Earth is pushed up • Deep ocean trenches – Earth’s crust pushed down and creates trench – Some plunge +10,000 meters below surface • This plain covers ½ of the surface of Earth The Ocean Floor Ocean Currents • Currents are caused by: – – – – Gravity Wind Heat from the surface Earth’s rotation • Effects on Earth’s climate: – Keep land cooler in summer (water takes time to cool off – Keep land warmer in winter (water takes time to cool down) Surface Currents • Currents near the surface of the ocean produces by global winds – Warm water currents: Gulf Stream begins in the tropical region. ..flows NE from Caribbean Sea to Europe – Cool water currents: California current that forms near the poles and flow toward the equator down the West Coast of the U.S. (keeps water cooler in California than on the East Coast) Ocean Currents Ocean Zones • Each zone=unique types of plants and animals. • Zones are determined by depth of the water communities • As the depth increases, there is less light. Intertidal Zone • Area of the ocean between the levels of high tide and low tide • Most shallow and brightest ocean zone • Environment always changing – Low tide: organisms have to hide from hot sun (crabs buy themselves in mud) – High tide: have to protect against rough water (mussels open up to feed on plankton) Near Shore Zone • • • • Includes most of the ocean over continental shelf No deeper than 200 meters (relatively shallow) Receives a great deal of sunlight LOTS OF LIFE IN THIS ZONE! Open-Ocean Zone • Most of the water over the continental slope and abyssal plain • Most animals live near the surface, because that’s where the food is. • 1000 meters below surface and beyond – Little food – Little or no light – Life:difficult due to pressure of water (most lungs would crush – COLD, deep, dark – Makes up 90% of all oceans Coral Reefs • Some of the largest structures on Earth built by living organisms • Coral=animals • Live in shallow, sun-lit, near shore waters • Very delicate and easily damaged • Corals use minerals dissolved in ocean water to form hard outer skeleton – Living coral attaches to dead coral’s skeleton Coral Reefs Continued… • They provide: – Surfaces under water that sunlight reaches easily – Shelter for animals: sea urchins, sponges, surgeon fish, parrot fish – Living space for algae and some plants (seaweed and plankton are the main food source) – Most corals are polyps: mouth at end of body with stinging tentacles – Take up less than 1% of ocean floor (25% of marine species live on , in, or around this area!) Deep Ocean Vents • Ecosystem below 1,000 meters • Gets energy from chemical reactions NOT sunlight • Ecosystem uses bacteria from volcanic vents – Water spews out at around 662 degrees F. (a mix of sulfer and iron-based chemicals – Bacteria uses chemical NOT the sun for energy • Other organisms depend on the energy of bacteria. Some have no stomach or mouth…tubeworms!