Crustacean Chromatophore: Endocrine Regulation and Intracellular Signalling Systems

Abstract

Crustacean body coloration plays a major role in communication, cryptic and thermoregulatory behavior (Thurman 1990). The pigments ommochromes, melanins, carotenoids, purines, and pterines are synthesized and/or stored within specialized epidermal cells, or epidermal appendices, such as hair or cuticle. The so-called pigment cells or chromatophores possess multiple branching processes, and may also be present in the epidermal lining of internal organs (nerve cord, intestine, and gonads). Chromatophores may be grouped according to their pigment color and internal structure (Rao 1985). Melanophores possess black or brown granules, erythrophores have red color, xanthophores are yellow, leucophores possess white granules, and iridophores are iridescent due to light reflection. Although color pattern is genetically determined, many crustaceans have the ability to change body coloration in response to exogenous or endogenous stimuli. Most species display a slowly changeable color pattern associated with ontogenetic, dietary, or seasonal determinants. These slow and long-lasting changes result from alterations in chromatophore number and/or pigment amount within the cells, and will not be discussed here. The Malocostraca, particularly some species of amphipods, euphausiids, mysids, stomatopods, isopods, and decapods, can also display rapid color changes as an immediate response to environmental changes, such as background color, light intensity, or social context.