1. Chapter 15 Animals of the Benthic Environment
Essentials of Oceanography
7th Edition

2. Benthic organisms
Benthic organisms are those that live in or on the ocean floor
More than 98% of known marine species are benthic
The vast majority of benthic species live within the shallow continental shelf

3. Benthic biomass closely matches surface productivity
Figure 13-6
Benthic biomass
Figure 15-1

4. Rocky shores Most organisms live on the surface (epifauna)
Zonation of rocky shores:
Spray zone (rarely covered by water)
High tide zone
Middle tide zone
Low tide zone (rarely exposed)
Upper zones have mostly shelled organisms
Lower zones have many soft-bodied organisms and algae

5. Rocky shores: Intertidal zonation and organisms
Figure 15-2a

6. Sea anemone
A vicious predator cleverly disguised as a harmless flower but armed with stinging cells
Figure 15-4

7. Sediment-covered shores
Most organisms burrow into the sediment (infauna)
Sediment-covered shores include:
Beaches
Salt marshes
Mud flats

8. Sediment-covered shores: Intertidal zonation and organisms
Figure 15-8

9. Sediment-covered shores: Modes of feeding
Figure 15-9

10. How a clam burrows
Figure 15-10

11. Shallow offshore ocean floor
Extends from the spring low-tide shoreline to the edge of the continental shelf
Mostly sediment-covered but contains rocky exposures
Includes:
Kelp forests
Coral reefs

12. Kelp forests
Kelp forests are found on rocky bottoms and provide habitat for many organisms
Gant brown bladder kelp Macrocystis has a strong holdfast and gas-filled floats
Macrocystis can grow up to 0.6 meter (2 feet) per day
Figure 15-15a

13. Coral reefs
Coral reefs are hard, wave-resistant structures composed of individual coral animals (polyps)
Individual coral polyps:
Are about the size of an ant
Are related to jellyfish
Feed with stinging tentacles
Live attached to the sea floor in large colonies
Construct hard calcium carbonate structures for protection
Contain symbiotic photosynthetic zooxanthellae algae

14. Coral reefs: Environmental conditions
Coral reefs need:
Warm water: 18-30°C (64-86°F)
Strong sunlight (for symbiotic algae)
Strong wave/current action
Lack of turbidity
Salt water
Hard substrate for attachment
Coral reefs found in shallow, tropical waters

15. Coral reef distribution and diversity
Figure 15-18

16. Coral reef zonation
Figure 15-19

17. Stages of coral reef development
Figure 2-30

18. Coral bleaching
Coral bleaching occurs when symbiotic zoothanthellae algae is removed or expelled
Associated with high water temperatures
Figure 15B

19. The deep-ocean floor Characteristics of the deep ocean:
Absence of sunlight
Temperatures around freezing
Average salinity
High dissolved oxygen
Extremely high pressure
Slow bottom currents (except abyssal storms)
Low food supply

20. Food sources for deep-sea organisms
Figure 15-22

21. Deep-sea hydrothermal vent biocommunities
Found in deep water near black smokers along the mid-ocean ridge
Do not rely on food from sunlit surface waters
Organisms include:
Tube worms
Clams
Mussels
Crabs
Microbial mats

22. Alvin approaches a hydrothermal vent biocommunity
Figure 15-23

23. Locations of deep-sea biocommunities
Figure 15-24

24. Deep-sea vent biocommunity food source: Chemosynthesis
Deep-sea vent biocommunities rely on bacteria and archaeon that chemosynthesize
Figure 15-25

25. Other deep-sea biocommunities
Low-temperature seep biocommunities are associated with:
Hypersaline seeps
Hydrocarbon seeps
Subduction zone seeps

26. Essentials of Oceanography 7th Edition
End of Chapter 15
Essentials of Oceanography
7th Edition