1. The Diversity of Ocean Life 15.2

2. Plankton
• Passively drifting or weak swimming
organisms that cannot move independently of
ocean currents.

3. Phytoplankton
• Algal plankton, the most important
community of primary producers in the
ocean.

4. Zooplankton
• Animal plankton.

5. Nekton
• Organisms that can move independently of
ocean currents by swimming or other means
of propulsion.

6. Benthos
• The forms of marine life that live on or in the
ocean bottoms.

7. Photic Zone
• The upper part of the ocean into which
sunlight penetrates.

8. Intertidal Zone
• The area where land and sea meet and
overlap; the zone between high and low tides.

9. Neritic Zone
• The marine-life zone that extends from
the low-tide line out to the shelf break.

10. Oceanic Zone
• The marine-life zone beyond the continental
shelf.

11. Pelagic Zone
• Open ocean of any depth; animals in this zone
swim or float freely.

12. Benthic Zone
• Othe marine-life zone that includes any sea-
bottom surface regardless of its distance from
shore.

13. Abyssal Zone
• A subdivision of the benthic zone
characterized by extremely high pressures,
low temperatures, low oxygen, few nutrients,
and no sunlight.

14. Key Concept
• How can marine organisms be
classified?
–Marine organisms can be classified
according to where they live and how
they move.

15. Key Concept
• What is the difference between
plankton and nekton?
–Plankton drift with ocean currents and
Nekton swim independently of the
ocean currents.

16. Key Concept
• In which area of the ocean can most
benthos organisms be found living?
–Most benthos organisms are living on
or in the ocean bottom.

17. Key Concept
• What factors are used to divide the
ocean into 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 water depth.