1. Chapter 12 The Marine Habitat
Essentials of Oceanography
7th Edition

2. The diversity of marine life
The ocean is home to a wide variety of organisms
Marine organisms range from microscopic bacteria and algae to the largest animal in the world (blue whale)
Number of known marine species: 250,000

3. Classification of living things
Organisms can be classified into one of three domains of life:
Archaea
Bacteria
Eukarya
Figure 12-1

4. Classification of living things
Organisms can also be classified into one of five kingdoms:
Monera
Protoctista
Fungi
Plantae
Animalia
Figure 12-1

5. Classification of living things
Taxonomic classification includes the following increasingly specific groupings:
Kingdom
Phylum (Division for plants)
Class
Order
Family
Genus
Species

6. Taxonomic classification of selected organisms
Category
Human
Killer whale
Giant kelp
Kingdom
Animalia
Protoctista
Phylum
Chordata
Phaeophyta
Subphylum
Vertebrata
Class
Mammalia
Phaeophycae
Order
Primates
Cetacea
Laminariales
Family
Hominidae
Delphinidae
Lessoniaceae
Genus
Homo
Orcinus
Macrocystis
Species
sapiens
orca
pyrifera

7. Classification of marine organisms
Marine organisms can be classified into one of three groups based on habitat and mobility:
Plankton (floaters)
Phytoplankton (drifting plants and algae)
Zooplankton (drifting animals)
Nekton (swimmers)
Benthos (bottom dwellers)

8. Plankton: Examples
Phytoplankton
Zooplankton
Figure 12-2

9. Nekton: Examples
Figure 12-4

10. Benthos: Examples
Figure 12-5

11. Life cycle of a squid
Squid experience benthic, planktonic, and nektonic stages
Squid are considered meroplankton (opposite = holoplankton)
Figure 12-3

12. Distribution of species on Earth
The land has more species because it has greater environmental variability than the ocean
Most ocean species are benthic because of greater environmental variability compared to pelagic environments
Figure 12-6

13. Adaptations of organisms to the marine environment
The marine environment presents many challenges to organisms because seawater:
Is dense enough to support organisms
Has high viscosity
Experiences variations in temperature and salinity
Contains variable amounts of dissolved gases
Has high transparency
Has a dramatic change of pressure with depth
Marine organisms have various adaptations for the conditions of the marine environment

14. Need for physical support
Condition:
Seawater is dense enough to support marine organisms
Adaptations:
Many marine organisms lack rigid skeletons, appendages, or vast root systems
Instead, they rely on buoyancy and friction to maintain their position within the water column

15. Seawater’s viscosity controlled by temperature
Condition:
Seawater’s viscosity (resistance to flow) is strongly affected by temperature
Cold water has higher viscosity than warm water, so is more difficult to swim through
Warm water has lower viscosity, so organisms tend to sink within the water column

16. Seawater’s viscosity controlled by temperature
Adaptations:
Many warm-water organisms have ornate appendages to say afloat
Many cold-water organisms are streamlined to swim more easily
Warm-water copepod
Cold-water copepod
Figure 12-7

17. Seawater’s viscosity and adaptations of phytoplankton
Condition:
Phytoplankton must remain in sunlit surface waters
Adaptations:
Small size increases surface area to volume ratio
Appendages increase frictional resistance
Tiny droplet of low density oil increases buoyancy
Figure 12-8

18. Variations in temperature
Condition:
Coastal water temperatures vary more than the open ocean or at depth
Adaptations:
Many coastal organisms can withstand a wide temperature range (are eurythermal)
Most open ocean and deep-water organisms can withstand only a small temperature range (are stenothermal)

19. Variations in salinity
Condition:
Coastal environments experience greater salinity variation than the open ocean or at depth
Adaptations:
Many shallow-water coastal organisms can withstand a wide salinity range (are euryhaline)
Most open ocean and deep-water organisms can withstand only a small change in salinity (are stenohaline)

20. Osmosis
Condition:
Osmosis is the movement of water molecules through a semipermeable membrane from higher to lower concentrations
Osmosis removes water from hypotonic organisms
Osmosis adds water to hypertonic organisms
Figure 12-13

21. Osmosis
Adaptations:
Figure 12-14

22. Dissolved gases: Oxygen
Condition:
Marine animals need oxygen to survive
Adaptations:
Many marine animals use gills to extract dissolved oxygen from seawater
Marine mammals must breathe air
Figure 12-15

23. Abundance of dissolved oxygen and nutrients with depth
Figure 12-20

24. Seawater’s high transparency
Condition:
Seawater has high transparency
Adaptations:
Transparency
Camouflage
Countershading
Migration (DSL)
Camouflage
Countershading
Figure 12-17

25. The deep scattering layer (DSL)
Organisms within the deep scattering layer undertake a daily migration to hide in deep, darker waters during daytime
Figure 12B

26. Increase of pressure with depth
Condition:
Pressure increases rapidly with depth
Adaptations:
Most marine organisms lack large compressible air pockets inside their bodies
Water-filled bodies exert the same amount of pressure as is pushing inward, so marine organisms do not feel the high pressure at depth

27. Divisions of the marine environment
Main divisions:
Pelagic (open sea)
Benthic (sea bottom)
Figure 12-19

28. Essentials of Oceanography 7th Edition
End of Chapter 12
Essentials of Oceanography
7th Edition