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Adaptations
Living things are found throughout the world in habitats with vastly
differing environmental conditions.
An organism is more likely to survive if it has structures or behaviour
which helps it obtain what it needs to survive and reproduce. We call
these features adaptations, and we say that the organism is well adapted
to its environment if it can survive there well.
Organisms show adaptations to assist movement, communication, survive
in different climates.... life is a matter of "survival of the best
adapted"!
It is of benefit to an organism if it is able to colonise a new area or
utilise a different food source because the organism then does not have to
compete against others for limited resources.
Because of this, we find
even among similar organisms, such as birds, many different varieties with
different features (adaptations) offering some benefit to aid
survival.
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Birds and beaks
The different beaks of birds are adaptations to allow
them to use different foods. This reduces competition and helps
survival.
- Seed-eaters require short vice-like beaks
for crushing hard seeds, e.g. budgerigar.
- Predatory birds require long, sharp, tearing
beaks for grasping animals and ripping through flesh, e.g.
eagle.
- Nectar feeders have a long thin beak with a
brushed tongue for nectar gathering, e.g.
honeyeater.
- Fish gatherers may have a large pouched beak
to store fish, e.g. pelican.
- Worm and shellfish eaters may have a long
spoon-shaped bill for burrowing in the sand, e.g.
spoonbill.
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Birds and feet
Birds'
feet are also adapted to their environmental conditions.
- Swamp or estuarine birds have long wading legs with wide feet
to prevent sinking in the mud, e.g. heron or stilt.
- Branch-dwelling birds have strong small gripping feet, e.g.
parrot.
- Predatory birds need large talons for gripping and carrying
small prey, e.g. falcon.
- Water birds (e.g. swans or ducks) have feet which are adapted
with webbing which acts like a paddle for swimming.
Charles Darwin studied finches in the Galapagos Islands during
his exploration on the ship, "The Beagle"(1835).
He found that several species of finches co-existed on the same
island because each had their own niche, eating different diets and
living in different areas (e.g. ground-dwellers, tree-dwellers and
so on). Each showed different adaptations specialising them for
their specific roles. This prompted his Theory of Evolution Through
Natural Selection (see Species and Evolution). |
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Same environment - similar
features
Looking at one habitat, e.g. the inter-tidal zone at
the beach, most creatures living there have some means of adhering to the
rock to prevent them being washed off by the waves. Shellfish have a
strong muscular foot, sea anemones are firmly attached and move only very
small distances, and starfish have sucker feet - all adaptations to allow
them to overcome this environmental problem.
Man and domesticated
organisms
Adaptations are usually beneficial changes, but
sometimes the benefits are for us rather than the organism! By selective
breeding, humans have changed some organisms to provide themselves with
more food. For example, larger, more docile and meatier cattle produce
more food for us, but these features certainly wouldn't help a cow survive
in the wild!
Selective breeding in dogs and cats for show purposes also
is based on Man's preferences, and not for the individual's survival.
Via genetic engineering, Man has also modified organisms to
improve such factors as yield, resistance to disease, and other
characteristics which improve survival.
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