Level 3 Bio Animal Responses

Taxic Response

Is the movement of a whole organism or cell in response to an external directional stimulus. The response could be away from the stimulus (negative) or towards the stimulus (positive).

Kinesis

The non-directional movement of an organism in responses to a stimulus in which the rate of movement depends on the intensity (rather than the direction) of the stimulus - e.g. A slater movers slowly in a damp atmosphere and quickly in a dry one.

Klinokinesis

Rate of turning is determined by the intensity of a stimulus. Increased chance of an animal finding favorable conditions.

Orthokinesis

Speed of an animals movement is determined by the intensity of a stimulus. Increased chance of an animal finding favorable conditions.

Phototaxis

movement toward or away from light

Thigmotaxis

the motion or orientation of an organism in response to a touch stimulus.

Rheotaxis

movement toward or away from a current

Positive phototaxis

An organism responds to light by moving towards it.

example: moths to a light

negative chemotaxis

movement of a cell away from a repellant or potentially harmful compound

Example of Kinesis

woodlice increase rate of movement/turning when they reach a dry area. this will allow them to reach a favourable damp area, where they don't turn as much.

Homing

The ability of an animal to find its way home over unfamiliar territory

Photokinesis

Is an orientation response of an organism. Like phototaxis, it is a response to light, however it is not a directional response, but rather a diffuse one

Migration

Is the seasonal mass movement of a population from one geographically defined location to another and back again.

Stellar Navigation

Uses the position of the stars to determine the direction to fly on their migration journey.

Magnetic navigation

The birds use the magnetic fields that surround the Earth to determine the direction they should head on their migration journey

Solar navigation

The animal uses the position of the sun to determine the direction to travel on their migration journey

Landmarks

To guide their journey and navigate their journey (this is less likely for the new fledglings as they have not travelled the migration route) e.g. the coastline or mountain range - harder to use when flying over water.

Sense of smell

The animal may also use scents or scent trails as adults can use the scent of the ocean and the scents of nearby landmasses to guide their way.

Cue for Migration

Is most likely day length as seasonal migrants must know what time of year it is. The most common and reliable cue is day length (photoperiod)

Survival Advantage - Passing on Favourable Genes

By making the migration, only the birds best adapted for the migration are able to survive the journey. This ensures that only the best alleles in the population survive and are passed on at breeding. This means that the population will be a collection of the alleles that best support survival in the current conditions.

Preparing for Migration

Due to the long distance, the animal requires a large amount of energy, therefore need to eat a lot, to lay down fat reserves required for the long journey. If they do not do this, then the godwit might not be able to complete the migration.

Costs of Migration

Cost to the individual is that a bird could be blown off course in a storm event during migration. The animal may become disorientated due to adverse weather conditions disrupting the celestial (sun / star) compass, not allowing effective navigation during the migration and be blown off course, lose too much energy, and die.

Timing of Migration

The timing of migration is sometimes affected by maturation because as the sex organs mature, there is a need or desire to reproduce.

Environmental cues

A drop in temperature and a shortening in the length of the day. E.g. changes in the length of the day are sensed directly through the skin and feathers by the pineal gland. This triggers migratory restlessness (zugunruhe)

Genetic drive

Some behaviour is genetic and innate, and is endogenously controlled.

Advantages of Migration

They can leave more offspring, as their offspring have a higher chance of survival. • They have a constant supply of food, reducing predation / parasitism / disease. • Greater genetic mixing. • Better breeding conditions. The animals remain in favourable temperatures; this means that they will not use as much energy to keep warm. • They can grow larger and store energy reserves for the return trip.

4 Disadvantages of Migration

• They could get lost or blown off course and not have enough energy to complete the journey. • They might get eaten by predators. • They might starve. • Its huge investment in energy

Negative phototaxis

E.g. a taxis is a movement that has direction, away from or towards a stimulus. (In this case movement of maggots away from light.)

Homing - Long definition from One Note

Is the return of an individual to its home site, sometimes over considerable distances. The base to which the individual must return includes the sheltering nests or burrows of mammals and birds and the colonial hives or nests of social insects. Animals must leave these homes to find food or sometimes mates and need to be able to return to feed offspring or to shelter from climatic extremes.

Navigation

Involves an animal finding its way over unknown territory to a known destination. During the journey the animal must know where it is in relation to its destination.