6.1.6 Causes of Animal Movement

Types of Stimuli Leading to Movement

1. External Stimuli:

• Examples: Light, sound, temperature, chemicals.
• Animals may move towards beneficial stimuli (positive response) or away from harmful ones (negative response).
• Example: A moth flying towards light (positive phototaxis).

2. Internal Stimuli:

• Examples: Changes in blood glucose levels, hunger, or dehydration.
• Internal stimuli trigger movements that maintain homeostasis.
• Example: An animal moving to find water when dehydrated.

3. Predation or Danger:

• Animals may move to escape predators or environmental hazards.
• Example: A rabbit running away from a fox.

Mechanisms of Movement

1. Nervous System Coordination:

• Stimuli are detected by receptors.
• Nerve impulses travel to the central nervous system (CNS), where decisions are made.
• Motor neurones send signals to effectors (muscles) to create movement.

2. Hormonal Control:

• Hormones like adrenaline can prepare the body for movement in response to danger (fight or flight).
• Example: Increased heart rate and respiration during escape.

3. Skeletal and Muscular System:

• Muscles contract to generate force, moving bones via the skeletal system.
• Example: A cheetah running involves rapid contraction of leg muscles.

4. Innate vs. Learned Responses:

• Innate movements are automatic and genetically programmed (e.g., reflexes).
• Learned movements are developed through experience (e.g., hunting techniques).

Adaptations for Movement

1. Morphological Adaptations:

• Wings for flight (e.g., birds).
• Fins for swimming (e.g., fish).
• Legs for running (e.g., mammals).

2. Physiological Adaptations:

• High numbers of mitochondria in muscle cells for ATP production.
• Aerobic respiration for sustained activity; anaerobic respiration for bursts of energy.

3. Behavioural Adaptations:

• Migratory movements to find resources.
• Avoidance of predators by hiding or fleeing.