What are georeceptors

Definition:


The receptors which are respond to the force of gravity are called georeceptors.

Explanation:


The give animal information about its orientation, "up and down".

Types of georeceptors:


There are following types of georeceptors

Statocysts


Most georeceptors have statocysts. Statocysts consists of fluid-filled chamber. This chamber is  lined with sensory epithelium. This epithelium has cilia. Solid granules are present within the chamber. These granules are called statolith (lithos stone). Any movement of animal changes the position of statolith. It moves the fluid. It alters the intensity and pattern of information arising from the sensory epithelium. For example; an animals moves. It moves the statolith fluid over the sensory epithelium. This movement provides information about the position of of animal relative to the environment.


Statolith is found in following animals:



  1. Gastropods

  2. Cephalopods

  3. Crustaceans

  4. nemertines

  5. Polychaete

  6. Scyphozoans


These animals use information in different ways. e.g.

a. Burrowing invertebrates can't rely on photoreceptors for orientation or direction. They depend on georeceptors for orientation within the substratum.

b. Planktonic animals orient in three dimensional aquatic environment with the help of statocysts. This specially important at night and in deep water.

Air bubbles


Many aquatic insects detect gravity from air bubbles. These air bubbles are trapped in certain passage ways (i.e. tracheal tubes). The carpenters level also uses air bubbles for orientation to gravity. The air bubbles stimulate (raise levels of physiological or nervous activity in (the body or any biological system) sensory bristles. These sensory bristles line the tubes.

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