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
|
|
Benthos: Dwellers of the Sea Floor
|
Notes on Topic:
The notes represent summaries of key issues
for each topic
They emphasize the terminology used to describe
the various phenomena.
| 1. Life on the ocean floor: |
| Learning Objectives: |
-
Comprehension of habitats and lifestyle of benthic organisms
-
Understanding of the characteristics of plant and animal forms of benthos
|
| 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).
|
| 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
|
| 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
|
| 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
|
| 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
|
| Deep Ocean Benthos: |
-
Deposit-feeding animals dominate:
-
predators like brittle stars, crinoids, mollusks, crustaceae
-
typically smaller than shallow-water relatives
-
adapted to food scarcity
|
| 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.
|
| 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.
|
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
|
