1. Earth’s Oceans
Part 4: Ocean Life Zones

2. 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?

3. Three Major Groups of Organisms
Grouped according to their habits and where in the water they live
Plankton - floaters
Nekton - swimmers
Benthos – bottom dwellers

4. 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

5. Plankton
Phytoplankton, primarily diatoms and dinoflagellates along with brown algae and cyanobacteria, use photosynthesis to make food.
Source of food for zooplankton

6. 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
Photo by Hofikai

7. 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:

8. 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

9. 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

10. Major Life Zones Three major environments or life zones: Intertidal
Neritic
Open-Ocean
Photosynthetic Zone
Bathyal
Abyssal
Hadal

11. 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

12. 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.

13. 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.

14. 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

15. 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

16. 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

17. 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: