Download Evolution and Life in the Ocean

Characteristics of All Living Things
• contain matter in a highly organized state
• can capture, store and transmit energy
• are capable of reproduction
• can change through time and adapt to their
environment
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Evolution and Life in the Ocean
Earth’s organisms have changed, or evolved, over the
course of 4 billion years.
Evolution occurs through the process of natural
selection.
The environment favors individuals that are well adapted.
Their favorable traits are retained because they contribute
to the organism’s reproductive success.
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Classification of Oceanic Life
Living things on Earth share many characteristics. Linnaeus
developed some of the systems used to name and classify
organisms.
• One of the first to use a system of natural classification
• Developed a classification system based on hierarchy
• Developed a system of scientific names for organisms
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The Three Domains
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Classification of Living Things
The six kingdoms of
living things
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Classification of Oceanic Life
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Major Groups
l
l
l
Plankton - free floating organisms
Nekton - swimmers
Benthos - bottom dwellers (on, in or
attached)
Epifauna - live on the bottom (attached or
free)
l Infauna - organisms that live in or burrow in
the sediment
l
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Classification of the Marine
Environment
The marine environment is divided into
zones - areas with homogeneous physical
features.
Zones are classified by location and the
behavior of the organisms found there.
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Classification of the Marine Environment
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Limiting Factors
Limiting factor - factor found in the
environment that can be harmful if present in
quantities that are too large or too small.
Any factor required for life can become a
limiting factor.
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Physical Factors Affecting
Marine Life
Any aspect of the physical environment that affects living organisms is
a physical factor.
The most important physical factors for marine organisms are:
light
dissolved gases
temperature
acid-base balance
salinity
hydrostatic pressure
dissolved nutrients
buoyancy
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Figure 13.8
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Figure 13.9
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Physical Factors Affecting
Marine Life
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Body Temperatures
l
l
Ectotherms - cold-blooded organisms;
body temperature determined by
environmental conditions (all marine
organisms except birds and mammals)
Endotherms - warm-blooded organisms;
maintain near-constant body temperature
(birds and mammals)
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Organisms and Ocean
Together
Biological factors also affect organisms in the ocean.
Some biologic factors that affect ocean organisms:
• feeding relationships
• crowding
• metabolic wastes
• defense of territory
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Diffusion, Osmosis, and Active
Transport
Organisms in the ocean rely on these processes for
many life functions.
Diffusion is mixing due to random molecular movements.
Osmosis is diffusion of water through a membrane
Active transport is the transport of a substance against a
concentration gradient. Active transport requires energy input.
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Diffusion, Osmosis, and Active Transport
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Biogeochemical Cycles
Cycles of elements that are important in life
processes.
Carbon - present in all organic molecules
Nitrogen - found in proteins and nucleic acids
Phosphorus and silicon – found in rigid parts of organisms
Iron and trace metals - used for electron transport
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Carbon Cycle
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Marine Communities
The J-shaped curve represents the growth of a population without
competitors for food or space. The S-shaped curve represents population
growth when the population encounters environmental resistance.
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Marine Ecology
* Marine organisms are found in communities, groups of interacting
producers, consumers, and decomposers that share a common
living space.
* The organisms found in a particular community depend on the
physical and biological characteristics of the living space.
* Symbiotic relationships are common in the ocean. Most forms of
marine life are actively involved in them.
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Organisms Within Communities
Terms for describing organisms and their
environments:
Habitat - an organism’s physical location in its
community
Niche - an organism’s role in the community
Biodiversity - the variety of species in a given area
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Physical and Biological Factors
A proper balance of physical and biological factors is
important for the success of each organism and the
community.
Different organisms have different tolerances for specific
factors.
Steno- is a prefix meaning “narrow”. It can be used to
describe organisms that have narrow tolerances for
specific factors
Eury- is a prefix meaning “wide”. It can be used to
describe organisms that have wide tolerances for specific
factors
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Physical and Biological Factors
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Changes in Marine Communities
Marine communities change through time. Changes can
occur slowly due to climate cycles or seafloor spreading,
or quickly due to factors such as volcanic eruption.
A climax community is a stable, long established
community.
If a climax community is disrupted, it may be restored
through the process of succession.
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Examples of Marine Communities
l Rocky
intertidal
l Seaweed
l Beach
l Salt marsh and estuary
l Coral reef
l Open ocean
l Deep sea floor
l Hydrothermal and cold vents
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Rocky Intertidal Communities
The most important physical factor in a rocky intertidal community is the
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rise and fall of tides.
Seaweed Communities
Seaweed provides protection and high
productivity to the animals that live in
seaweed communities.
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Salt Marshes and Estuaries
Salt marshes and estuaries are rich in
nutrients, but organisms must cope with
fluctuating salinity in these
environments.
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Hydrothermal Vent and Cold
Seep Communities
Many chemosynthetic organisms are found near hydrothermal vents and
cold seeps.
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Symbiotic Interactions
Symbiosis is the close interaction of the lives of
two species.
Types of symbiotic interactions:
Mutualism - both organisms benefit in these
relationships.
An example is sea anemones and anemone fish.
Commensalism - one organism benefits, the other is not
helped or harmed.
Parasitism - one of the organism benefits, but the other is
harmed.
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