Oceans in Motion Vocab

Oceans in motion vocab abyssal plain The flat, deep ocean floor. It is almost featureless because a thick layer of sediment covers the hills and valleys. algae A small single-celled plant. amphibious Able to operate on land and in the water. aphotic zone Bottom most layer of the ocean zones, where light does not reach. atoll Coral reefs sometimes grow around seamounts that rise above the surface of the ocean. As the seamount sinks or its peak erodes, the seamount will disappear beneath the water leaving the coral ring. baleen large stiff plates that grow down from the gums of the whale’s upper jaw, allow whales to filter feed. Baleen is made of keratin, the same protein that makes up hair and fingernails, and is strong, yet elastic. Beaufort Wind Scale a system developed by a British hydrographer, Sir Frances Beaufort, in 1805 to describe wind force at sea. benthic environment the sea floor benthic life plants and animals that live on the ocean floor. blowhole(s) a single or pair of breathing organs of whales and dolphins on the dorsal (back) surface of their head. At the surface, they quickly inhale and relax the muscular flap to close it so they can dive. blue water waters that lie beyond the coastal shallows (coastal ocean). coastal downwelling a type of vertical current that arises when onshore winds (or winds blowing toward the shore) push water toward the coast. This drives the nearshore surface water down and away from the coast. coastal upwelling a type of vertical current that arises when offshore winds (or winds blowing toward the ocean) push water away from the shore and deep, colder water rises to replace the water that has been blown out into the ocean. This cold water from deep off the ocean floor brings many nutrients to the surface. continental margin is the continental slope, which is still considered part of the continent, together with the continental shelf. continental rise as currents flow along the continental shelf and down the continental slope, they pick up and carry sediments along and deposit them just below the continental slope. These sediments accumulate (gather) to form the large, gentle slope of the continental rise. continental shelf break where the bottom sharply drops off into a steep slope. It usually begins at 430 feet (130 meters) depth and can be up to 20 km wide. continental slope connects the continental shelf and the oceanic crust. deep ocean basin is about 2.5 to 3.5 miles deep, covers 30 % of Earth’s surface and has features, such as abyssal plains, deep-sea trenches and seamounts. deep-sea trenches are the deepest parts of the ocean. The deepest one, the Marianas Trench in the South Pacific Ocean, is more than 33,000 feet, or almost 5 miles (8.05 kilometers) deep. deposition the buildup of sediment or sand. diurnal tides tides that occur once a day. A body of water with diurnal tides, like the Gulf of Mexico, has only one high tide and one low tide in a 24-hour period. duration the length a gust of wind blows. dysphotic zone middle layer of ocean zones where light can be measured, sometimes as deeply as a kilometer down, but is too faint to support photosynthesis. ebb tidal currents that are moving away from the beach. echolocation a method by which marine mammals explore their environment and objects. Pulses of ultrasonic (the frequency is too high to be heard by humans) sound is sent out through the blowhole. When the sound waves bounce off objects in their path, a portion of the signal is reflected back. By measuring the time between sending out the sound and its return, these marine mammals can find out the size, shape, direction, and distance of an object. This system of sensing the environment is an advantage in orientation, navigation, and capturing prey in dark or turbid waters. emergent coast a category of primary coast that results from the land being lifted, either by tectonic activity or rebound from the weight of heavy glaciers, which exposes the former sea bottom bit by bit forming continuously new shoreline. erosion the wearing away of soil or rock. euphotic zone topmost layer of ocean zones and is defined by how deeply photosynthetic life can be found. fetch the distance the wind blows. filter feeders creatures that pull small bits of organic material, like plankton and larvae, from the water as it moves past them. fjords u-shaped valleys formed by glacial action. Fjords are found in areas with long histories of glacier activity, like northern Europe, Alaska and Canada. flood tidal currents that are moving toward the beach. guyot a seamount whose peaks have eroded and become a flat surface gyres the large rotating loops generated from currents flowing in circular motion. herbivores animals that eat only vegetation. holdfasts root-like structures of plants to help hold on to the rocky bottom. keratin the same protein that makes up hair and fingernails, and is strong, yet elastic longshore current a current found along the coast that flows parallel to the beach. This current is caused when waves strike the beach at an angle. The front part of the wave hits the shallow water first and slows down. The rest of the wave bends as it comes onto the shore creating a current that parallels the beach. Larger waves, which strike the beach less often at greater angles, create stronger longshore currents. In areas where longshore currents often occur, sandbars form. marine terraces a characteristic feature of emergent coasts formed as tectonic uplift moves the land upward in short bursts, which are then worn by wave action into relatively flat surfaces, somewhat like a large staircase. mid-ocean ridge two chains of mountains separated by a large depression that form at a spreading center. mixed tides a single low tide follows two high tides. Parts of the Pacific Basin contain mixed tides. mutualism beneficial relationship between organisms. myoglobin the oxygen-binding protein found in blood. It stores oxygen and helps prevent muscles from losing oxygen. neap tides Phenomenon in which very little difference exists between high and low tides. Neap tides happen when the alignment of the Earth, Moon, and Sun form a right angle. Opposite of spring tides. necrotic zone the first 200 meters (656 feet) of ocean water, which includes the seashore and most of the continental shelf. northeast and southeast trade winds the winds at the equator that blow in one direction all year. oceanic zone extends from 200 meters (656 feet) deep all the way down to the bottom of the ocean, which can be thousands of meters deep. olfactory sense of smell osmosis the process where water flows from a low salinity environment through a membrane to a higher salinity environment to try and equal out the salt content on both sides of the membrane. pelagic environment the ocean waters phytoplankton one of the tiny drifing ocean organisms that uses light energy to convert carbon dioxide and water into food. pinnipedia a latin word meaning "feather-footed" and refers to the flippers of pinnipeds, which are shaped like wings or feathers. plunging breakers waves that occur on beaches where the slope is moderately steep. This kind of wave normally curls over forming a tunnel until the wave breaks. polar easterlies the winds at the highest latitudes that blow in one direction all year. polyps members of individual coral colonies. Polyps consist of a tube and an oral disc, or mouth, surrounded by tentacles, which the polyps use to capture food. primary coasts coasts created by non-marine processes because of changes in the land, such as river deltas or lava flows. rift valley a large depression. rip currents can happen when longshore currents, which move parallel to the beach, bounce seaward because of a change in the bottom’s structure. Also known as rip tides. river delta a type of primary coast formed where a river deposits soil and other material as it enters the sea. river-dominated delta a type of delta formed when there are large amounts of material in the water, and tidal action is relatively low. seamount began life as volcanoes formed over hot spots in the ocean floor. After the crust moves off the hot spot, the volcanic activity stops. secondary coasts coast formed by marine action because of changes in the ocean, such as the creation of barrier islands or coral reefs. semi-diurnal tides tides that occur twice a day. This means a body of water with semi-diurnal tides, like the Atlantic Ocean, will have two high tides and two low tides in one day. spilling breakers waves that occur on beaches with gentle slopes. These waves break far from the shore, and the surf gently rolls over the front of the wave. spit Narrow peninsula of sand along the coast formed by longshore currents carrying large amounts of sand. spreading center where two plates are drifting apart. spring tides Phenomenon in which a very large difference between high and low tides exists. For a spring tide to occur, the Earth, Moon, and Sun must be in a straight line. submergent coast A category of primary coast that results from a general sea-level rise and crustal subsidence. Most of the eastern United States has submergent coastlines. One example is the Chesapeake Bay. submersible a great scientific tool to help researchers explore the ocean depths. They are small submarines that can maneuver underwater easier than larger submarines. Submersibles are equipped with viewports (windows), searchlights, mechanical arms, cameras and scientific instruments that enable seeing and recording data from underwater vehicles. surging breakers waves that occur on beaches where the slope is very steep. The wave does not actually break. Instead, it rolls onto the steep beach. These kinds of breakers are known for their destructive nature. tectonic activity changes in the structure of the rock and soil because of earthquakes. tidal current horizontal current associated with tides that can be described as either ebb or flood. tidal range measurement of the difference between the high and low tides. Tidal ranges can be measured in inches, like those in Lake Superior, Michigan, or tidal ranges can be measured in feet, like those in the Bay of Fundy in Alaska. tide-dominated delta a type of delta found where the daily tidal range is more than a meter; it has many branching channels and long narrow islands formed as the tide and river flow in different directions. tombolos narrow sand deposits connecting a near-shore island with the beach. trough valley between two waves; the lowest point on a wave. tsunami The most dramatic and destructive of waves caused by underwater disturbances, such as volcanoes, earthquakes, and landslides. These waves can reach heights of 120 feet (40 m) or more. The larger the disturbance, the larger the tsunami will be. turbidity currents are bottom currents that carry lots of sediment undulating a way marine mammals swim by moving their hindquarters from side to side wave height a vertical distance between a wave’s crest and the next trough. wave period measures the size of the wave in time. A wave period can be measured by picking a stationary point and counting the seconds it takes for two consecutive crests or troughs to pass it. wave-dominated delta little more than a bulge on the shoreline since there is so much wave activity that all the sediment is spread evenly along the coast and does not accumulate at the river’s end. wavelength the horizontal distance either between the crests or troughs of two consecutive waves. westerlies the winds at the mid-latitudes that blow in one direction all year. zooplankton is the floating creatures ranging from microscopic diatoms to small fish and shrimp. zooxanthellae a single-celled algae living within each coral polyp to provide food to the polyps by photosynthesis.