Chapter 15 Animals of the Benthic Environment

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 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. End of Chapter 15 Essentials of Oceanography 7th Edition