Transcript Orientation Responses

Orientation
Responses
Animal
General
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Orientation repsonses are ones where the
animal positions itself or carried out specific
behaviours when an environmental factor
changes direction, duration or intensity
They can range from simple ones (taxes,
kinesis) to changes in factors such as light,
humidity or touch, to complex behaviours
such as migration or homing
These responses help organisms avoid
adverse conditions
Taxis
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Movement of the whole animal towards or
away from a stimulus that is uni-directional
Movement towards the stimulus is positive
Movement away from the stimulus is
negative
Tactic responses are named according to the
kind of stimulus
negative taxis
away from
the stimulus
positive taxis
towards the
stimulus
Stimulus
Kinesis
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Random movement response
Activity rate it determined by intensity of stimulus
rather than direction
Neither positive nor negative
If the organisms speed is effected it is termed
orthokinesis
If the organisms rate of turning is effected it is
termed klinokinesis
These responses may be modified by the animals
internal state
Migration
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Regular, annual mass movements
Move from breeding area to another area
where they do not breed and eventually back
again
It is carefully planned
Behaviour must be inherited, and maintained
by natural selection
Advantages
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Animals remain in a favourable temperature
They grow larger
They leave more offspring
They have a constant supply of food
It may lead to the colonisation of a new area
Reduces predation/parasitism disease
Greater genetic mixing
Better breeding conditions
Disadvantages
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They may get lost or caught in a storm
They may get eaten by a predator
They may use up too much energy in the
migration, leading to exhaustion
They may starve
It’s a huge investment in energy
Triggers
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The behavioural trigger that sets off migratory
behaviour varies
Maturation – as sex organs mature and there
is a need or desire to reproduce
Environmental clues – such as a drop in
temperature and shortening of day length
Genetic drive – some behaviour is genetic
and some learned, star patterns are learned
but how to learn them is innate
Homing
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The ability of an individual to return to the
home site
This may be a hive, nest, mound, burrow etc
The home provides food, warmth shelter and
protection for young
Animals have to leave the home for food and
to find mates but need to be able to find it
again
Methods of homing and
Migration
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Methods used to find home and for migration
are often the same
Some animals use more than one method
There is a certain amount of learning involved
Piloting
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An animal moves from one familiar landmark
to another until it reaches its destination
This is used over short distances
It uses visual cues
Compassing
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An animal can detect a compass direction
and travels in a straight-line path until it
reaches its destination
It can use:
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Magnetic field lines
Chemical clues
Sound
Navigation
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Involves determining one’s position relative to
other locations
Two things are required for both solar and
stellar navigation:
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Map sense – the ability to be aware of lattitude
and longitude of an area
Sense of timing – an internal clock