15.2

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15.2 The Diversity of Ocean Life
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Do Now

• How are marine organisms classified?

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Do Now

• How are marine organisms classified?
• According to where they live and how they move.

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Key Words

• Marine
• Propulsion

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Vocab Words

• Benthos
• Nekton
• Plankton

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Classification of Marine Organisms

• Marine organisms can be classified according to
  where they live and how they move.
• Plankton
• Nekton
• Benthos

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Plankton

• Plankton include all organismsalgae, animals,
  and bacteriathat drift with ocean currents. They
  are also known as drifters.
• Planktos wandering

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Plankton

• Phytoplankton - are algae plankton, which are the
  most important community of primary producers in
  the ocean. They undergo photosynthesis. They
  are microscopic. Ex Diatom
• Zooplankton - are animal plankton. Include the
  larval stages of marine organisms. Such as fish,
  crab, shrimp, etc.

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Nekton

• Include all animals capable of moving
  independently of the ocean currents, by swimming
  or other means of propulsion.
• Includes most adult whale, squid, shark and fish.

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Benthos

• Describes all organisms living on or in the ocean
  bottom.
• Most benthos organisms can be found in shallow
  intertidal zone.

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Marine Life Zones

• Three factors are used to divide the ocean into
  distinct marine life zones the availability of
  sunlight, the distance from shore, and the water
  depth.

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Availability of Sunlight

• The photic zone is the upper part of the ocean
  into which sunlight penetrates.
• The aphotic zone is the lower part of the ocean
  into which no sunlight exists.

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Distance from Shore

• The intertidal zone is the strip of land where
  the land and ocean meet and overlap, or the zone
  between high and low tides.
• The neritic zone is the marine-life zone that
  extends from the low-tide line out to the shelf
  break.
• The oceanic zone is the marine-life zone beyond
  the continental shelf.

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Water Depth

• The pelagic zone is open zone of any depth.
  Animals in this zone swim or float freely.
• The benthic zone is the marine-life zone that
  includes any sea-bottom surface regardless of its
  distance from shore.
• The abyssal zone is a subdivision of the benthic
  zone characterized by extremely high pressures,
  low temperatures, low oxygen, few nutrients, and
  no sunlight.

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Hydrothermal Vents

• Here seawater seeps into the ocean floor through
  cracks in the crust.
• At some vents, water temperatures of 100oC or
  higher support communities of organisms found
  nowhere else in the world.

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Group Challenge Question

• It has been observed that some species of
  zooplankton migrate vertically in ocean water.
  They spend the daylight hours at deeper depths of
  about 200 meters and at night move to the
  surface. Formulate a hypothesis that might
  explain this behavior.