Overview:

Orientation responses divided into either simple responses or complex responses. Both types are innate responses

Simple responses: Taxes (sing. taxis) and kineses (sing. kinesis)

• Occur to abiotic factors ie. light, humidity, chemicals, heat.

• Helps remove the animal from unfavourable conditions into favourable conditions

Complex responses: Homing and migration

• May occur over long distances + time frame to a predetermined location

• Navigation influenced by external abiotic factors

• Homing and migration arise from internal factors

• Not in direct response to either favourable or unfavourable conditions

Prefixes

photo- light

thermo- temperature

geo/gravi- gravity

chemo- chemical

thigmo- touch

hydro- water

rheo- current

tropho - food

Taxes

• Definition: Innate movement response towards or away from a directional stimulus

  • Towards stimulus: positive taxis

  • Away from stimulus: negative taxis

• Examples of describing taxis responses:

  • Movement towards light: positive phototaxis

  • Movement away from light: negative phototaxis

• Adaptive advantage of taxis responses:

  Allows the animal to take a direct route away from unfavourable conditions, and towards more favourable conditions

Kineses

• Definition: Innate movement response to an external non-directional stimulus

  • Direction of movement is random + no relation to direction of stimulus

• Orthokinesis

  • Definition:

    The speed of an animal in response to a stimulus is proportional to the intensity of the stimulus causing the movement - unfavourable conditions = faster, favourable conditions = slower

• Klinokinesis

  • Definition:

    The rate of turning of an animal in response to a stimulus is proportional to the intensity of the stimulus.

    Unfavourable conditions = faster rate of turning

• Adaptive advantage of orthokinesis and klinokinesis:

  Fast speed + rapid turning = cover more ground at higher rate => higher chance of finding favourable environments

Homing

• Definition: An animal’s ability to return home over unfamiliar territory

• Activity rhythm: Can be daily, annually, or biennially

• Examples:

  • Honeybees return to their hive after foraging

    Daily/circadian rhythm

    Foraging may take them as far as 10km from the hive

  • Salmon will return to the river that they were born to breed

    They grow up + spend their adult lives at sea, and only return during breeding season

  • Adult Southern royal albatross or toroa (Diomedea epomophora) will return to the established breeding and nesting colony at the tip of the Otago Peninsula bienially (taking place every two years), to lay an egg, incubate it, to then have it hatch (September-November-February). They will also fly to find food daily, and regularly return to check on their chicks.

  All three examples above exhibit the ability to return home after finding food (often daily), or to breed (often annually or biennially)

Migration

• Definition: Mass movement of individuals from one geographical location to another over a long period of time

• Cyclical/Return migration:

  • Definition: Animals will exhibit an annual cycle of migration from breeding grounds to feeding grounds (overwintering grounds).

  • For some, cyclical migration will occur at different stages in their life instead of annually

• One way migration:

  • Definition: Migration that involves leaving the home range for a new location and never returning to the original home range

  • Eg. Migrants die at the end of migration

• Migration preparation: Controlled by their biological clock

  • Building up their fat reserves to ensure an energy supply for the journey

  • Moulting feathers + replacing them with new ones => ensure maximum flight efficiency

Navigation

• Animals need to use navigation methods to find their way home (homing) or to travel to overwintering or breeding grounds (migration) over unfamiliar territory

• Navigation is innate, but skill can be improved through experience

• Often animals will need to use a combination of navigation methods to increase the success of migration

  • Eg. An animal that usually uses solar navigation may need to use magnetic or topographical navigation on cloudy days.

• Topographical memory

  • Navigation system using visual cues like landmarks.

  • More common in homing responses with familiar landmarks

  • Migrating animals may use coasts, islands, mountain ranges or rivers etc

• Solar navigation - Sun compass

  • Navigation system using the sun as a compass as it moves across the sky from east to west during the day

  • By maintaining a set angle with the sun, the animal is able to move in a straight line

  • The animal’s biological clock compensates for the sun’s movement and allows it to change its position relative to the sun accordingly

  • Bees and migratory animals use a Sun compass

• Stellar navigation - Star compass

  • Where animals can navigate by orientating to star patterns ie. constellations.

  • Animals in the northern hemisphere can locate the north by using the Pole Star

  • Animals in the southern hemisphere can locate the south by using the South Celestial pole (NOTE: This is not an actual star)

  • All migratory birds use a star compass

• Magnetic fields - Magnetic compass

  • Animals use the Earth’s magnetic field lines to navigate

  • Some birds such as pigeons have a spot of magnetite in their beaks to detect changes in the magnetic field

• Chemical navigation - Scent trails

  • Animals can use scent trails to find their way to a specific location

• Sound navigation - Sonar

  • Animals such as bats and dolphins can use echolocation to home

  • How: Sound waves are emitted that echo (bounce back) from objects and then they use the speed of the bounce back to position themselves in relation to the object