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

Whale shark eating 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 Uwe Kils 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 A Caridean Shrimp- 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

Photo credit: Réunion Underwater Photography 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 Octopuses and octopi are both correct Sperm Whales Photo credit:  Réunion Underwater Photography

Open-Ocean Zones Abyssal Zone: 2,000-6,000 meters No sunlight 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