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To understand the life in the sea we need to know something
about what shapes its habitats, forms the substrates it lives on, and
how dynamic (geologically) its home is.
Geology: physical and
structural foundations •  Earth is about 4.5 billion years old
•  The floor is about 0-200 Million years
•  The continents are about 1.5-3.8 Billion years
• Heat driven motion at the earth s core causes convection currents and causes flowing and movement of the solid surfaces above (such as the plates)
solid
solid but flows
mostly solid
liquid
Solid: 7200 deg F
4000 deg. C!
Crusts… •  Both oceanic and continental crust are less dense (lighter) than the mantle below, causing
them to float on it (and flow too)
•  Oceanic crust is
•  mostly basalt
•  denser than continental (so floats lower, and is covered
By water)
•  thinner than continental crust
•  overall younger (not exceeding about 200 million years)
•  Continental crust is
•  mostly granitic
•  overall lighter and thicker than oceanic crust
•  overall older (as much as 3.8 billion years)
The earth s crust moves: this creates ocean
boundaries (and continents): 4-5 major oceans
Plate tectonic basics •  Plates move up to 8-10 cm per year
•  Sometimes they crash into one another
This happens at convergent plate boundaries
Can create mountains on continents (convergent boundaries)
Can create subduction too (one plate moves under another)
•  Atlantic Ocean
•  Indian Ocean
•  Arctic ocean
•  Southern Ocean youngest, no land
barrier
•  Pacific ocean:
the deepest. Mariana trench is 11,000 meters deep (36,000 feet!)
•  Sometimes they pull apart
This sometimes creates spreading zones (mid ocean ridges)
This happens at divergent plate boundaries
• Sometimes they move alongside each other: Transform boundaries
Like the San Andreas fault
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Spreading happens when
Plates pull apart.
New oceanic crust is formed
When this happens
Mid ocean ridges
Subduction will happen when a heavy plate (such as an oceanic
Plate) hits a lighter one and goes under it.
Continental margins
Active: tectonic activity, subduction (eg. west coast of US)
Passive: depositional (eg. east coast of US)
Subduction of an oceanic plate under a continental plate
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Passive vrs. active continental margins
Continental margins •  Continental shelf: created by erosion
(they are a terrestrial feature)continental crust. Biologically rich. To about 200 M depth.
•  Continental slope: steep, boundary between continental and oceanic
crust. Submarine canyons. To 3,000 - 4,000 M depth.
•  Continental rise: sediment accumulation. Turbidity currents. Mud
and sand.
•  Abyssal plain: 4,500 - 6,000 M depth. Oceanic crust below. Mostly
flat and soft sediment. Manganese nodules and other resources
undiscovered .
• Deep sea trenches: to 11,300 M deep. Subduction zones. ?????
Manganese nodules
Chemistry and Physics of the ocean:
we also have to understand something about
the abiotic (non-living) physical and chemical
components of the habitat of living organisms
Key chemical factors
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•
•
•
•
•
•
•
The special properties of water
Temperature – thermal considerations
Density
Sound
Salinity (dissolved solids)
Gases
Light
Relationships
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The Magic of Water
Properties of Water
•
•
•
•
•
•
2. Excellent biological
solvent 3. High heat capacity
4. High thermal conductivity
5. Less dense when frozen
1. Cohesion and adhesion
2. High specific heat
3. High heat of evaporation 4. High thermal conductivity
5. Less dense when frozen
6. Excellent biological solvent
+
H
H
H
+
+
Hydrogen Bonding
O
O
+
H
H
+
O
H +
H +
H
+
O
H+
O
H+
The water molecule: polar bonding
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Open Ocean Swell
Wave Height
Cormorant
at the surface
5 m
4 m
3 m
2 m
P
1 m
Direction of wave propagation
In the diagram above, the planktonic organism ( ) wouldP
a. soon be carried to the Cormorant.
b. drift further away from the Comorant because it cannot
swim.
c. move in a circle but stay the same relative distance from the
Cormorant.
d. soon be eaten by the Cormorant.
The wave height is equal to:
a. 1 meter
b. 2 meters
c. 3 meters
d. 4 meters
Wave Height
5 m
4 m
3 m
2 m
1 m
The wave height is equal to:
a. 1 meter
b. 2 meters
c. 3 meters
d. 4 meters
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