Hormones Controlling Other Functions

Crustacean's exhibit pronounced capacity for physiological color changes. It is known that the color changing mechanisms in Crustacea are regulated by hormones. The animals have a range of chromatophores consisting of different pigments: the melanophores usually contain black pigments. Many crustaceans are brilliantly colored animals and they have the capacity to change their body color. Body color is often because of colored pigments present within certain cells. The cells concerned are called chromatophores. Color change may be

(1) Either because of synthesis of new pigments or destruction of existing pigments. In other words it is because of a quantitative change in the pigments of the body. This type of color change called morphological color change is very slow, taking considerably long time to accomplish.

(2) Though, animals can as well change their color without recourse to synthesis or destruction of pigments. That is, there is no change in the quantity of pigments present. This involves movement of already existing pigment granules in the chromatophores. When the pigment granules within the chromatophores are concentrated at a point, the cells appear pale or blanch; while the pigment granules are dispersed throughout the cell, it appears brightly colored. This sort of color change is called physiological color change, and is comparatively more rapid as compared morphological color change.