NOTES
Links to summaries of key issues for each topic
VISUALS
Links to images employed in lectures on a topic-by-topic basis
TEXT
Link to chapter outlines at online learning center at McGraw Hill.
NOTES
Links to summaries of key issues for each topic
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Marine Animals and Communities
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Notes on Topic:
The notes represent summaries
of key issues for each topic
They emphasize the terminology used to
describe the various phenomena.
| 3. Life on the ocean floor: |
| Learning Objectives: |
- Comprehension of habitats and lifestyle of benthic communities
- Understanding of the characteristics of plant and animal forms of
benthic communities
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| Plants: |
- Attached plants:
- e.g. kelp, a large brown benthic algae
- occurs in subtropical to subpolar nutrient-rich waters
- attached by holdfasts that anchor plants
- buoyed by gas-filled bladders with fronds (blades).
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| Animals: |
- Infauna:
- buried animals, deposit or filter feeders
- Epifauna:
- Strategies:
- attachment: filtering of seawater
- free movement: predation
- burrowing: sediment digestion
- Influences on diversity include:
- food availability, temperature, salinity, character of sediment/rock
- stability of bottom environment affects diversity,
- nfluenced by waves
- organisms tend to decrease away from land as food supply decreases
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| Intertidal Zone: |
- Typically a zonation dependent on tide levels:
- assemblages of plants and animals in each zone
- competition for living space, especially shelters from winds, waves
- plants include green, red and brown algae
- dependent on light, temperature, grazed by animals
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| Rocky Shore Communities: |
- Highest level wetted by spray,
- highest tides demands resistance to drying
- littoral zone between high and low tides requires firm attachment
- tide pools contain specialized organisms
- adapted to conditions that may change rapidly
- rocky offshore regions favor
- crabs, starfish, sea anemones, sea urchins etc., lobsters and octopus
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| Muddy and Sandy Bottom Communities: |
- Marshes, beaches and estuaries
- colonized by sea grasses except where:
- waves and currents remove fine particles and organic matter
- Sandy environments
- inhabited by infauna governed by sediment grain size
- coarse sands favor suspension feeders
- fine muds favor ingestion
- burrowers that may pump water
- fecal pellets from deposit feeders may bind sediments
- reducing turbidity and excluding suspension feeders
- burrowing stirs sediment (bioturbation) aiding aerobic bacteria
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| Deep Ocean Benthos: |
- Deposit-feeding animals dominate:
- predators like brittle stars, crinoids, mollusks, crustaceae
- typically smaller than shallow-water relatives
- adapted to food scarcity
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| Coral Reefs: |
- Occur in tropical and subtropic waters >18°C
- colonial animals that build calcareous skeletons forming structures
- dependent on reef position
- associated symbiotic zooxanthellae (dinoflagellate algae) live in
corals
- providing products and moderating CO2 levels
- provide habitats for invertebrates and fish
- cyanobacteria provide nitrogen.
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| Vent Communities: |
- Depend on chemosynthesis by bacteria
- supports food chains of worms, clams, crabs, fish
- organisms adapted to environment
- clams protect themselves from high H2S levels
- cold and hot (hydrothermal) vent communities known
- vent communities also found at oil seeps.
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Department of Geological Sciences,
1001 E. Tenth Street, Bloomington, IN 47405-1403
Phone: (812) 855-5582 Last updated: 7 December 2000
Comments: simon@indiana.edu
Copyright
2000, The Trustees of Indiana University
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