1. The Discovery of Ocean Life
Most marine organisms live within the sunlit surface waters
Algae needs sunlight to grow and is at the bottom of the ocean’s food web
Therefore most animals need to live near or travel to the surface to find food

2. Classification of Marine Organisms
Plankton
Plankton
Any organism that is free floating (drifts with the surface current)
Phytoplankton: photosynthesizing organisms, usually algae
Zooplankton: animals (usually fish, sea star, and crustacean larvae) and copepods

3. Classification of Marine Organisms
Nekton
Any organism that can swim independently of the oceans currents
Most adult fish, squid, marine mammals, and marine reptiles

4. Classification of Marine Organisms
Benthos
Any organism that lives on or in the ocean’s floor
Sea stars, crustaceans, and kelps

5. Marine Life Zones
Three factors are used to divide the ocean into distinct marine zones
Availability of Sunlight
Distance from Shore
Water Depth

6. Marine Life Zones Availability of Sunlight
Photic Zone: the upper part of the ocean that receives sunlight
Euphotic Zone: the upper portion of the photic zone where photosynthesis can occur
Aphotic Zone: the part of the ocean that receives no sunlight

7. Marine Life Zones Distance from Shore
Intertidal Zone: the narrow area of the ocean between the low and high tide lines
Organisms have to deal with the harsh sun but they have a better chance of avoiding predators
High Tide
Low Tide

8. Marine Life Zones Distance from Shore
Neritic Zone: the area starting from the lowest low tide to the end of the continental shelf
This zone is ideal for many species and supports 90% of the world’s commercial fisheries
Continental Shelf

9. Oceanic Zone: the open ocean beyond the continental shelf
Marine Life Zones
Distance from Shore
Oceanic Zone: the open ocean beyond the continental shelf
This zone has lower nutrient concentrations which results in smaller populations
Continental Shelf
Open Ocean

10. Marine Life Zones Water Depth
Pelagic Zone: the open ocean at any depth
-Plankton need sunlight for photosynthesis and surface currents to carry them
-Nekton free-swim and feed
-Larger Oceanic predators
-Deep ocean organisms

11. Marine Life Zones Water Depth
Benthic Zone: any ocean floor surface regardless of distance from shore

12. Marine Life Zones Water Depth
Abyssal Zone: a subdivision of benthic zone - high pressures, low temps, low oxygen, few nutrients & no sunlight.

13. Hydrothermal Vents
Most vents are found at mid-ocean ridges and trenches and can reach 100˚C (212˚F-boiling)
When super-heated water meets cold seawater, minerals and metals precipitate out of the water to form smoker
Bacteria perform chemosynthesis (no light=no photosynthesis) to support this unique food web