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Earth’s Oceans. Part 4: Ocean Life Zones. Factors that Affect Life in the Ocean. Amount of sunlight Temperature of the water Water pressure How does depth affect each of these? Where would you expect to find the greatest abundance of organisms?. Three Major Groups of Organisms.
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Earth’s Oceans Part 4: Ocean Life Zones
Factors that Affect Life in the Ocean • Amount of sunlight • Temperature of the water • Water pressure • How does depth affect each of these? • Where would you expect to find the greatest abundance of organisms?
Three Major Groups of Organisms • Grouped according to their habits and where in the water they live • Plankton - floaters • Nekton - swimmers • Benthos – bottom dwellers
Plankton • Float at or near the surface (up to 200 m deep in open ocean) • Plankton comes from the Greek word planktos that means drifting • Many are microscopic • Foundation of the ocean food web Whale shark eating plankton http://commons.wikimedia.org/wiki/File:Whale_shark_eating_plankton.JPG
Plankton • Phytoplankton, primarily diatoms and dinoflagellates along with brown algae and cyanobacteria, use photosynthesis to make food. • Source of food for zooplankton
Plankton • Zooplankton includes animal-like protists (radiolarians, forminiferans, ciliates and zooflagellates), jellyfish, siphonophores such as the Portuguese man-of-war, and copepods and krill (two types of crustaceans) Krill Photo credit: Jamie Hall, NOAA Copepod photo by UweKils Model of a radiolarian at the Smithsonian Museum http://www.flickr.com/photos/23165290@N00/7282108674 Photo by Hofikai
Nekton • All the organisms that swim freely in the ocean, independent of current • Live in shallow or deep water Three main types: • Cordates - bony fish, whales, sharks, turtles, snakes, eels, porpoises, dolphins and seals • Molluscan – octopus and squid • Arthropods - shrimp Video of nekton in the depths of the ocean: http://ocean.si.edu/ocean-videos/sea-creatures-deep-video-national-geographic-and-census-marine-life
Nekton Great White Shark A young loggerhead sea turtle Photo by Irvin Calicut ACarideanShrimp- moves primarily by swimming Common Octopus Photo by Albert Kok Bottlenose Dolphin
Benthos • Organisms that live on the ocean floor Includes: • Plants - seagrass • Protists – brown, red, and green algae (seaweed) • Many invertebrate animals – sea stars, sea anemones, sponges, sea urchins, oysters, clams, crabs, sponges, coral, etc. Sally Lightfoot Crab Photo by Peter Wilton
Major Life Zones Three major environments or life zones: • Intertidal • Neritic • Open-Ocean • Photosynthetic Zone • Bathyal • Abyssal • Hadal
Intertidal Zone • The region between high tide and low tide • Most changeable zone • Varies back and forth from dry to under water twice a day • Organisms must also withstand the affects of waves breaking on the shore. Photo Credit: Eric Guinther
Intertidal Zone • Many organisms attach themselves to rocks so as to avoid being washed out to sea. • Others burrow into the wet sand • Starfish, barnacles, anemones, seaweed, sea urchins, clams, mussels, hermit crabs, etc. live here. A beautiful array of starfish , sea urchins and mussel shells in the rocky intertidal zone of Kachemak Bay.
Neritic Zone • From low-tide line to edge of continental shelf, down to about 200 meters • Also called coastal waters • Plenty of sunlight for photosynthesis • Plankton, nekton, and benthos all found here • Richest life zone in the ocean A close-up of a small mass of sargassum weed. The numerous small round spheres are floats filled with carbon dioxide. These provide buoyancy to the algae.
Open-Ocean Zones Photosynthetic Zone – • Extends from the ocean surface to approximately 200m • Sunlight penetrates the entire zone • Plankton and nekton live in this zone
Open-Ocean Zones Bathyal Zone: • Begins at continental slope and continues to depths of about 2,000 meters • Water temperature about 4°C • Little if any light, so no photosynthesis • Many forms of nekton live here including whales, squids, and octopuses • Benthos organisms also live here, including sponges and sea stars • Great biodiversity in this zone Sperm Whales Photo credit: Réunion Underwater Photography
Open-Ocean Zones Skeleton of a Glass Sponge Abyssal Zone: • 2,000-6,000 meters • No sunlight • Great pressure • Temperature 2-4°C • Creatures that live here may be blind or bioluminescent Giant Squid Photo: NTNU Museum of Natural history and Archeaology
Open-Ocean Zones Hadal Zone: • Very deepest parts of the ocean, below the abyssal zone • Totally dark • Immense pressure • Creatures removed from this zone will die in the lower-pressure areas above. • The most common creatures found here include jellyfish, viperfish, tube worms, sea cucumbers and deep sea angler fish. • Video: http://www.telegraph.co.uk/earth/earthvideo/9168817/James-Camerons-first-footage-from-the-deep.html