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Earth’s OceansPart 4: Ocean Life Zones
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Factors that Affect Life in the Ocean1. Amount of sunlight2. Temperature of the water3. Water pressure
How does depth affect each of these?
Where would you expect to find the greatest abundance of organisms?
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Three Major Groups of OrganismsGrouped according
to their habits and where in the water they live
1. Plankton - floaters2. Nekton -
swimmers3. Benthos – bottom
dwellers
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PlanktonFloat 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 planktonhttp://commons.wikimedia.org/wiki/File:Whale_shark_eating_plankton.JPG
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PlanktonPhytoplankton,
primarily diatoms and dinoflagellates along with brown algae and cyanobacteria, use photosynthesis to make food.
Source of food for zooplankton
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PlanktonZooplankton
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)
KrillPhoto credit: Jamie Hall, NOAACopepod
photo by Uwe Kils
Model of a radiolarian atthe Smithsonian Museum
http://www.flickr.com/photos/23165290@N00/7282108674Photo by Hofikai
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NektonAll 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
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Photo by Irvin Calicut A young loggerhead sea turtle
Great White Shark
Common OctopusPhoto by Albert KokBottlenose Dolphin
A Caridean Shrimp- moves primarily by swimming
Nekton
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BenthosOrganisms that live
on the ocean floorIncludes: 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 CrabPhoto by Peter Wilton
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Major Life ZonesThree major environments or life zones:
IntertidalNeritic Open-Ocean
Photosynthetic ZoneBathyalAbyssalHadal
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Intertidal ZoneThe region between
high tide and low tideMost changeable zoneVaries 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
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Intertidal ZoneMany 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.
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Neritic ZoneFrom 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.
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Open-Ocean ZonesPhotosynthetic Zone – Extends from the ocean surface to
approximately 200mSunlight penetrates the entire zonePlankton and nekton live in this zone
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Open-Ocean ZonesBathyal 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 WhalesPhoto credit: Réunion Underwater Photography
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Open-Ocean ZonesAbyssal Zone:2,000-6,000 metersNo sunlightGreat pressureTemperature 2-4°CCreatures that live
here may be blind or bioluminescent
Giant SquidPhoto:
NTNU Museum of Natural history and
Archeaology
Skeleton of a Glass Sponge
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Open-Ocean ZonesHadal Zone:Very deepest parts of
the ocean, below the abyssal zone
Totally darkImmense pressureCreatures 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