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Mechanism of Reflex Action and Explanation of Taxis

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Reflex actionBiology | Zoology Notes
Mechanism of Reflex Action and Explanation of Taxis
For: Science Class 11 | Animal Behavior

The movement or response of animal with their environment is called animal behavior. There are three types of animal behavior.

Reflex action
The quick or immediate response toward stimulus is called reflex action. This is automatic or unconscious. The reflex action is also known as automatic response. There are two types of reflex action:

Simple reflexes : Simple reflexes are inborn or unlearned, for example closing of eyes when an object approaches and secretion of saliva in mouth seeing sweet or sour food.
Conditional reflexes : The responses brought about by learning or experiences, for example ringing a bell and secretion of saliva in dog.

Mechanism of Reflex Action
The centre of reflex action is spinal cord ; The afferent fiber or sensory fiber enters the spinal cord through the dorsal root and carry the impulse from the effectors organ to spinal cord. The efferent fiber or motor fiber passes through the ventral root and carries impulses away from the spinal cord to the effectors organ. The adjustor neuron in spinal cord communicates between afferent and efferent neuron.

The movement of animals towards or away from the stimulus is called the taxis. The taxis may be negative or positive. The movement away from stimulus is called negative taxis and the movement towards the stimulus is called positive taxis.

  • Thermotaxis: it is response to the stimulus of temperature. For example during winter we attract toward heat and in summer we go away from the heat.
  • Phototaxis: it is the response to stimulus of light. For example, the cockroach and earthworm go away from the light. The euglena move towards light.
  • Geotaxis: the response to stimulus of gravity is called geotaxis. Earth worm move deep into the soil.
  • Rheotaxis: the response to the stimulus of water current. Flow towards direction of water current.
  • Chemotaxis it is response to chemicals. The mosquitos fly away from the burning coil.
  • Sociotaxis: it is response to the groups or family. The man attract toward the family.
  • Klinotaxis: In some organism the receptor cells are distributed on body surface, mostly on dorsal surface of anterior part. They try to orient their body by bending first on one direction and then other which continues until the receptor of two sides are equally stimulated. For example Euglena.
  • Tropotaxis: The orientation of body in response to a stimulus is straight, not sideways like klinotaxis due to presence of receptor organs in pair. for eg. Lice and ticks.
  • Telotaxis: The animals orient to any one of stimulus when they are stimulated by two sources of stimuli. The honey bee moves to flowers in presence of light and in evening she left flowers and moves to hives.
  • Menotaxis: The animals orient their body in response to stimulus at a constant angle. The ant move in a path guided by the direction of sun.
  • Mnemotaxis: Some animals orient their body towards different types of stimuli. The wasps use light direction, land marks, and trial of chemicals left.
Posted By : Hari Prasad Chaudhary | Comment RSS | Category : Class XI, HSEB Notes
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