Part 4: Ocean Life Zones 1
Factors that Affect Life in the Ocean 1. Amount of sunlight 2. Temperature of the water 3. Water pressure How does depth affect each of these? Where would you expect to find the greatest abundance of organisms? 2
Three Major Groups of Organisms Grouped according to their habits and where in the water they live 1. Plankton - floaters 2. Nekton - swimmers 3. Benthos bottom dwellers 3
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 4
Plankton Phytoplankton, primarily diatoms and dinoflagellates along with brown algae and cyanobacteria, use photosynthesis to make food. Source of food for zooplankton 5
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) Copepod photo by Uwe Kils Photo by Hofikai Krill Photo credit: Jamie Hall, NOAA Model of a radiolarian at the Smithsonian Museum http://www.flickr.com/photos/23165290@n00/7282108674 6
Nekton All the organisms that swim freely in the ocean, independent of current Live in shallow or deep water Video of nekton in the depths of the ocean: http://ocean.si.edu/oceanvideos/sea-creatures-deep-videonational-geographic-and-censusmarine-life Three main types: Cordates - bony fish, whales, sharks, turtles, snakes, eels, porpoises, dolphins and seals Molluscan octopus and squid Arthropods - shrimp 7
Nekton Photo by Irvin Calicut A young loggerhead sea turtle Great White Shark Bottlenose Dolphin Common Octopus Photo by Albert Kok A Caridean Shrimp- moves primarily by swimming 8
Benthos Organisms that live on the ocean floor Includes: Plants - seagrass Many invertebrate animals sea stars, sea anemones, sponges, sea urchins, oysters, clams, crabs, sponges, coral, etc. Protists brown, red, and green algae (seaweed) Sally Lightfoot Crab Photo by Peter Wilton 9
Major Life Zones Three major environments or life zones: Intertidal Neritic Open-Ocean Bathyal Abyssal Hadal 10
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 11
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. 12
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. 13
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 14
Open-Ocean Zones Abyssal Zone: 2,000-6,000 meters No sunlight Great pressure Temperature 2-4 C Creatures that live here may be blind or bioluminescent Skeleton of a Glass Sponge Giant Squid Photo: NTNU Museum of Natural history and Archeaology 15
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 lowerpressure 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/e arth/earthvideo/9168817/jam es-camerons-first-footagefrom-the-deep.html 16