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

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

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

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

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

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

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

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

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

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

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

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

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